Continuous analyte sensor device and method

Abstract

There is provided a continuous (multi) analyte sensor device comprising a (multi) analyte sensor operably coupled to a signal transduction device, the (multi) analyte sensor comprising at least one membrane, the at least one membrane comprising at least one first transduction element, and at least one of a mediator and / or a regenerative cofactor.

Description

Technical Field

[0001] The present disclosure relates to continuous analyte sensor devices and methods and continuous multi-analyte sensor devices and methods. Background Art

[0002] In vivo analyte sensors can typically be configured to analyze a single analyte using an enzyme to provide specificity for the single analyte. Determining the concentrations of multiple analytes of physiological relevance may be desirable in certain medical situations. Continuous quantification of circulating analytes remains a major challenge in clinical medicine. Summary of the invention

[0003] In a first aspect, a continuous (multi) analyte sensor device is provided, which comprises a built-in (multi) analyte sensor operably coupled to a signal transducer, wherein the (multi) analyte sensor comprises at least one membrane system adjacent to the signal transducer, wherein the at least one membrane system independently comprises: a first layer comprising at least one first transduction element; and a second layer adjacent to the first layer, wherein the second layer is the same as or different from the first layer.

[0004] In one example, the signal transducer includes at least one electrode. In another example, alone or in combination with any of the preceding examples, the at least one electrode includes a first working electrode surface and a second working electrode surface vertically, horizontally, or circumferentially spaced apart from the first working electrode surface.

[0005] In another example, alone or in combination with any of the preceding examples, the first layer is adjacent to the first working electrode surface. In another example, alone or in combination with any of the preceding examples, the second layer is adjacent to the second working electrode surface. In another example, alone or in combination with any of the preceding examples, at least a portion of the first layer is adjacent to at least a portion of the first working electrode surface, and at least a portion of the second layer is further, vertically, horizontally, or circumferentially separated from at least a portion of the first working electrode surface than the portion of the first layer.

[0006] In another example, alone or in combination with any of the preceding examples, the second layer includes at least one second transduction element that is different from the first transduction element.

[0007] In another example, alone or in combination with any of the preceding examples, the device further comprises at least one of a mediator and a regeneration cofactor present in the first layer, the second layer, or both the first layer and the second layer, wherein the at least one mediator is operably associated with the at least one first transduction element or the at least one second transduction element.

[0008] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator and the at least one first transduction element, and the second layer includes at least one regeneration cofactor.

[0009] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0010] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one mediator.

[0011] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0012] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator, the at least one regeneration cofactor, and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0013] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, at least one mediator, and the at least one second transduction element, wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0014] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator and the at least one first transduction element, and the second layer includes the at least one regeneration cofactor.

[0015] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one mediator.

[0016] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator, the at least one regeneration cofactor, and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0017] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, at least one mediator, and the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0018] In another example, alone or in combination with any of the preceding examples, the at least one regeneration cofactor is one or more of NAD, NADH, NAD(P)H, NAD(P)+, mutant NAD+(nox) (or NADH oxidase or NADHox, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), pyrroloquinoline quinone (PQQ), and functionalized derivatives thereof.

[0019] In another example, alone or in combination with any of the preceding examples, the mediator or the at least one regeneration cofactor is covalently, electrostatically, ionically associated with one or more of the first layer, the second layer, or the third layer, or is physically trapped or absorbed by one or more of the first layer, the second layer, or the third layer. In another example, alone or in combination with any of the preceding examples, the mediator or the at least one regeneration cofactor is covalently, electrostatically, ionically associated with the one or more working electrode surfaces, or is physically trapped or absorbed by the one or more working electrode surfaces.

[0020] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0021] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0022] In another example, alone or in combination with any of the preceding examples, the first layer or the second layer comprises a polymer. In another example, alone or in combination with any of the preceding examples, the polymer is a polyolefin, a polystyrene, a polyoxymethylene, a polysiloxane, a polyether, a polyacrylate, a polymethacrylate, a polyester, a polycarbonate, a polyamide, a polypyridine, a poly(pyridine-styrene) copolymer, a poly(ether ketone), a poly(etherimide), a polyurethane, a polyurethane urea, a polycarbonate-polyurethane copolymer, or a blend thereof.

[0023] In another example, alone or in combination with any of the preceding examples, the device further includes at least one third transduction element present in at least one of the first layer, the second layer, and the third layer.

[0024] In another example, alone or in combination with any of the preceding examples, the first layer has a first diffusion resistance to one or more analytes or one or more substrate reaction products, and the second layer has a second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products, wherein the second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products is substantially the same as or different from the first diffusion resistance.

[0025] In another example, alone or in combination with any of the preceding examples, the one or more analytes include glucose, lactose, glycerol, beta-hydroxybutyrate, creatinine, creatine, alcohol, urea, uric acid, cholesterol, bilirubin, glutathione, urea, sodium, potassium, or glutamate.

[0026] In another example, alone or in combination with any of the preceding examples, the at least one first transduction element and the at least one second transduction element are independently selected from dehydrogenases, reductases, kinases, peroxidases, esterases, (amido)hydrolases, and oxidases.

[0027] In another example, alone or in combination with any of the preceding examples, the at least one first transduction element and the at least one second transduction element each have a substrate and produce a reaction product with the substrate and provide a clinical value associated with a health condition of a mammal. In another example, alone or in combination with any of the preceding examples, the substrate or the reaction product is selected from hydrogen peroxide, creatine, acetoacetate, dihydroxyacetone, oxygen, or an aldehyde.

[0028] In another example, alone or in combination with any of the preceding examples, the at least one first transduction element and the at least one second transduction element are β-hydroxybutyrate dehydrogenase, alcohol dehydrogenase, lipase, amide hydrolase, glycerol kinase, creatinine kinase, creatine amide hydrolase, alcohol oxidase, cholesterol oxidase, galactose oxidase, choline oxidase, glutamate oxidase, glycerol-3-phosphate oxidase, bilirubin oxidase, ascorbate oxidase, urate oxidase, urease, pyruvate oxidase, xanthine oxidase, glucose oxidase, lactate oxidase, sarcosine oxidase, malate dehydrogenase, formaldehyde dehydrogenase, glutathione reductase, glutathione peroxidase, 3-hydroxysteroid dehydrogenase, or horseradish peroxidase.

[0029] In another example, alone or in combination with any of the preceding examples, the mediator is one or more of 2,2′-bipyridine, poly-110-phenanthroline-5,6-dione, polyvinylferrocene, hexacyanoferric acid, phthalocyanine or their organometallic compounds, organometallic compounds of osmium or ruthenium and their functionalized derivatives, and complexes of one or more transition metals with one or more polymers or ligands and their salts.

[0030] In another example, alone or in combination with any of the preceding examples, the device further includes a transmitter configured to wirelessly transmit data to a paired display device or therapy delivery device such that multiple analyte parameters are evaluated in parallel.

[0031] In a second aspect, a continuous analyte sensor device is provided, which includes a built-in mediated analyte sensor operably coupled to a signal transducer, the mediated analyte sensor including at least one membrane system adjacent to the signal transducer, the at least one membrane system independently including: a first layer including at least one first transduction element; a second layer adjacent to the first layer, the second layer being the same as or different from the first layer; at least one mediator; and a mediated system interference domain, the mediated system interference domain including at least one oxidase, at least one peroxidase, catalase or a combination thereof.

[0032] In one example, the built-in mediated analyte sensor is a (multiple) analyte sensor. In another example, alone or in combination with any of the preceding examples, the built-in mediated analyte sensor is a glucose and ketone analyte sensor. In another example, alone or in combination with any of the preceding examples, the built-in mediated analyte sensor is a glucose and creatinine analyte sensor. In another example, alone or in combination with any of the preceding examples, the built-in mediated analyte sensor is a glucose and alcohol analyte sensor.

[0033] In another example, alone or in combination with any of the preceding examples, the signal transducer comprises at least one electrode. In another example, alone or in combination with any of the preceding examples, the at least one electrode comprises a first working electrode surface and a second working electrode surface vertically, horizontally, or circumferentially spaced apart from the first working electrode surface.

[0034] In another example, alone or in combination with any of the preceding examples, the first layer is adjacent to the first working electrode surface. In another example, alone or in combination with any of the preceding examples, the second layer is adjacent to the second working electrode surface.

[0035] In another example, alone or in combination with any of the preceding examples, at least a portion of the first layer is adjacent to at least a portion of the first working electrode surface, and at least a portion of the second layer is separated from at least a portion of the first working electrode surface further, vertically, horizontally, or circumferentially than the portion of the first layer.

[0036] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0037] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0038] In another example, alone or in combination with any of the preceding examples, the first layer includes at least one first transduction element and the second layer includes at least one second transduction element that is different from the first transduction element.

[0039] In another example, alone or in combination with any of the preceding examples, the at least one first transduction element and the at least one second transduction element each have a substrate and produce a reaction product with the substrate and provide a clinical value related to a health condition of a mammal.

[0040] In another example, alone or in combination with any of the preceding examples, the device further includes at least one regeneration cofactor present in the first layer, the second layer, or both the first layer and the second layer.

[0041] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator and the at least one first transduction element, and the second layer includes the at least one regeneration cofactor.

[0042] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one mediator.

[0043] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator, the at least one regeneration cofactor, and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0044] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one mediator, the at least one regeneration cofactor, and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0045] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, at least one mediator, and the at least one second transduction element, wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0046] In another example, alone or in combination with any of the preceding examples, the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, at least one mediator, and the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0047] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

[0048] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0049] In another example, alone or in combination with any of the preceding examples, the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

[0050] In another example, alone or in combination with any of the preceding examples, the device further comprises a third layer adjacent to the second layer. In another example, alone or in combination with any of the preceding examples, the device further comprises at least one third transduction element present in at least one of the first layer, the second layer, and the third layer.

[0051] In another example, alone or in combination with any of the preceding examples, the first layer has a first diffusion resistance to one or more analytes or one or more substrate reaction products, and the second layer has a second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products, wherein the second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products is, in another example, alone or in combination with any of the preceding examples, substantially the same as or different from the first diffusion resistance.

[0052] In another example, alone or in combination with any of the preceding examples, the at least one first transduction element and the at least one second transduction element are independently a dehydrogenase, a reductase, a kinase, a peroxidase, an esterase, a (amido)hydrolase, an oxidase, or a combination thereof.

[0053] In another example, alone or in combination with any of the preceding examples, the at least one first transduction element and the at least one second transduction element are independently β-hydroxybutyrate dehydrogenase, alcohol dehydrogenase, lipase, amide hydrolase, glycerol kinase, creatinine kinase, creatine amide hydrolase, alcohol oxidase, cholesterol oxidase, galactose oxidase, choline oxidase, glutamate oxidase, glycerol-3-phosphate oxidase, bilirubin oxidase, urease, pyruvate oxidase, xanthine oxidase, glucose oxidase, lactate oxidase, sarcosine oxidase, malate dehydrogenase, formaldehyde dehydrogenase, glutathione reductase, glutathione peroxidase, 3-hydroxysteroid dehydrogenase, or a combination thereof.

[0054] In another example, alone or in combination with any of the preceding examples, the mediator is one or more of 2,2′-bipyridine, poly-110-phenanthroline-5,6-dione, polyvinylferrocene, hexacyanoferric acid, phthalocyanine or their organometallic compounds, organometallic compounds of osmium or ruthenium and their functionalized derivatives, and complexes of one or more transition metals with one or more polymers or ligands and their salts.

[0055] In another example, alone or in combination with any of the preceding examples, the at least one oxidase is ascorbate oxidase or urate oxidase. In another example, alone or in combination with any of the preceding examples, the at least one oxidase is horseradish peroxidase.

[0056] In another example, alone or in combination with any of the preceding examples, the mediated system interference domain comprises at least one polymer. In another example, alone or in combination with any of the preceding examples, the at least one polymer is a polyolefin, a polystyrene, a polyoxymethylene, a polysiloxane, a polyether, a polyacrylate, a polymethacrylate, a polyester, a polycarbonate, a polyamide, a polypyridine, a poly(pyridine-styrene) copolymer, a poly(ether ketone), a poly(etherimide), a polyurethane, a polyurethane urea, a polycarbonate-polyurethane copolymer, polyethylene vinyl acetate, or a blend thereof.

[0057] In another example, alone or in combination with any of the preceding examples, the device further includes at least one of an electrode domain, an enzyme domain, a resistance domain, and an interference membrane.

[0058] In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is present in the electrode domain. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is directly adjacent to the electrode domain. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is present in the enzyme domain. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is directly adjacent to the enzyme domain. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is present in the resistance domain. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is directly adjacent to the resistance domain. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is present in the interference membrane. In another example, alone or in combination with any of the preceding examples, the mediated system interference domain is directly adjacent to the interference membrane.

[0059] In another example, alone or in combination with any of the preceding examples, the device further includes a transmitter configured to wirelessly transmit data to a paired display device or therapy delivery device such that at least two analyte parameters are evaluated in parallel.

[0060] In one example, a continuous analyte sensor device is provided, the device comprising an analyte sensor operably coupled to a signal transducer, the analyte sensor comprising at least one membrane system adjacent to the signal transducer, the at least one membrane system independently comprising: a first domain comprising at least one first transduction element; a second domain adjacent to the first domain, the second domain being the same as or different from the first domain; and at least one regeneration cofactor.

[0061] In one aspect, the analyte sensor is a multi-analyte sensor. In one aspect, alone or in combination with any of the preceding aspects, the multi-analyte analyte sensor is a glucose and ketone analyte sensor, or a glucose and creatinine analyte sensor, or a ketone and potassium ion analyte sensor.

[0062] In one aspect, alone or in combination with any of the preceding aspects, the signal transducer comprises at least one electrode.

[0063] In one aspect, alone or in combination with any of the preceding aspects, the first domain comprises at least one first transduction element and the second domain comprises at least one second transduction element, the second transduction element being different from the first transduction element.

[0064] In one aspect, alone or in combination with any of the preceding aspects, the at least one regeneration cofactor is one or more of NAD, NADH, NAD(P)H, NAD(P)+, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), pyrroloquinoline quinone (PQQ), and functionalized derivatives thereof.

[0065] In one aspect, alone or in combination with any of the preceding aspects, the device further comprises at least one mediator present in the first domain, the second domain, or both the first domain and the second domain. In one aspect, alone or in combination with any of the preceding aspects, the mediator is one or more of 2,2′-bipyridine, poly-110-phenanthroline-5,6-dione, polyvinylferrocene, hexacyanoferric acid, phthalocyanine or their organometallic compounds, organometallic compounds of osmium or ruthenium and their functionalized derivatives, and complexes of one or more transition metals with one or more polymers or ligands and their salts.

[0066] In one aspect, alone or in combination with any of the preceding aspects, the first domain comprises the at least one mediator and the at least one first transduction element, and the second domain comprises the at least one regeneration cofactor, or wherein the first domain comprises the at least one regeneration cofactor and the at least one first transduction element, and the second domain comprises the at least one mediator.

[0067] In one aspect, alone or in combination with any of the preceding aspects, the at least one first transduction element and the at least one second transduction element are independently a dehydrogenase, a reductase, a kinase, a peroxidase, an esterase, a (amido)hydrolase, an oxidase, or a combination thereof.

[0068] In one aspect, alone or in combination with any of the preceding aspects, the at least one first transduction element and the at least one second transduction element are independently β-hydroxybutyrate dehydrogenase, alcohol dehydrogenase, lipase, amide hydrolase, glycerol kinase, creatinine kinase, creatine amide hydrolase, alcohol oxidase, cholesterol oxidase, galactose oxidase, choline oxidase, glutamate oxidase, glycerol-3-phosphate oxidase, bilirubin oxidase, urease, pyruvate oxidase, xanthine oxidase, glucose oxidase, lactate oxidase, sarcosine oxidase, malate dehydrogenase, formaldehyde dehydrogenase, glutathione reductase, glutathione peroxidase, 3-hydroxysteroid dehydrogenase, NADH oxidase, or a combination thereof.

[0069] In one aspect, alone or in combination with any of the preceding aspects, the at least one first transduction element is a β-hydroxybutyrate dehydrogenase and the at least one second transduction element is a NADH oxidase.

[0070] In one aspect, alone or in combination with any of the foregoing aspects, the at least one electrode comprises platinum or palladium, an interference domain is deposited on the at least one electrode; the first domain is adjacent to the interference domain, the first domain comprises β-hydroxybutyrate dehydrogenase, NADH oxidase and the cofactor; and the second domain is adjacent to the first domain, the second domain comprises a polyvinylpyridine polymer or copolymer. In one aspect, alone or in combination with any of the foregoing aspects, the continuous analyte sensor device is configured to provide a continuous analyte signal in the absence of a transition metal-containing mediator.

[0071] In one aspect, alone or in combination with any of the preceding aspects, the at least one regeneration cofactor is NAD.

[0072] In one aspect, alone or in combination with any of the preceding aspects, the interference domain is configured to block diffusion of at least one of acetaminophen, ascorbic acid, bilirubin, cholesterol, creatinine, dopamine, ephedrine, ibuprofen, L-dopa, methyldopa, salicylate, tetracycline, tolbutamide, tolbutamide, triglycerides, and uric acid from the electrode.

[0073] In one aspect, alone or in combination with any of the preceding aspects, the interference domain comprises a polyurethane, a polyurethane-zwitterionic polymer, a polymer having ionic side groups, a NAFION TM , chitosan, cellulose, alternating layers of polyallylamine and polyacrylic acid, or combinations or blends thereof.

[0074] In one aspect, alone or in combination with any of the preceding aspects, the first domain or the second domain comprises an amphiphilic polymer or copolymer.

[0075] In one aspect, alone or in combination with any of the preceding aspects, the first domain or the second domain comprises a heterocyclic polymer or copolymer, or an at least partially quaternized heterocyclic polymer or copolymer.

[0076] In one aspect, alone or in combination with any of the preceding aspects, the device further comprises a transmitter configured to wirelessly transmit data to a paired display device or therapy delivery device. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to understand and appreciate how the present disclosure may be implemented in practice, examples will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0078] Figure 1A to Figure 1B Depicted are exemplary enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0079] Figure 1C to Figure 1D Depicted are exemplary enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0080] Figure 1E Depicted are exemplary enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0081] Figure 1F Depicted are exemplary experimental data for enzyme domain configurations as disclosed and described herein for use in continuous multi-analyte sensors.

[0082] Figure 1G Depicted Figure 1E Linear regression of the experimental data.

[0083] Figure 1HDepicted are exemplary experimental data for a cofactor / enzyme resistance domain configuration of a continuous analyte sensor as disclosed and described herein.

[0084] Fig. 1I Depicted are exemplary experimental data for a cofactor / enzyme resistance domain configuration of a continuous analyte sensor as disclosed and described herein.

[0085] Figure 1J Depicted are exemplary experimental data for a cofactor / enzyme resistance domain configuration of a continuous analyte sensor as disclosed and described herein.

[0086] Figure 2 Depicted are exemplary experimental data for enzyme domain configurations as disclosed and described herein for use in continuous multi-analyte sensors.

[0087] Figure 3A Depicted are exemplary experimental data for enzyme domain configurations as disclosed and described herein for use in continuous multi-analyte sensors.

[0088] Figure 3B Depicted Figure 3A Exemplary experimental data for the enzyme domain configuration of the continuous multi-analyte sensor.

[0089] Figure 3C Depicted is a series of exemplary experimental data for enzyme domain configurations of continuous multi-analyte sensors using different electrode compositions as disclosed and described herein.

[0090] Figure 4 Depicted are exemplary experimental data for enzyme domain configurations as disclosed and described herein for use in continuous multi-analyte sensors.

[0091] Figure 5 Depicted is a series of exemplary experimental data for an enzyme domain configuration of a continuous multi-analyte sensor as disclosed and described herein.

[0092] FIG. 6A to FIG. 6B Depicted are alternative views of exemplary dual-electrode enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0093] FIG. 6C to FIG. 6D Depicted are alternative views of exemplary dual-electrode enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0094] Fig. 6E An exemplary two-electrode configuration for a continuous multi-analyte sensor as disclosed and described herein is depicted.

[0095] Fig. 6F Depicted Fig. 6A Exemplary experimental data for a two-electrode configuration of a continuous multi-analyte sensor to FIG.

[0096] Fig. 7A Depicted are exemplary enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0097] Figure 7B Depicted Fig. 7A Exemplary experimental data for enzyme domain configuration.

[0098] Figure 7C , Fig.7D Alternative exemplary enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein are depicted.

[0099] Fig. 7E Depicted Fig.7D Exemplary experimental data for enzyme domain configuration.

[0100] Fig. 8A Depicted are exemplary enzyme domain configurations for use in continuous multi-analyte sensors as disclosed and described herein.

[0101] Figure 8B , Figure 8C Depicted Fig. 8A Exemplary experimental data for enzyme domain configuration.

[0102] 9A to 9D Depicted are alternative views of exemplary two-electrode enzyme domain configurations G1-G4 for use in continuous multi-analyte sensors as disclosed and described herein.

[0103] Fig.9E Depicted Fig. 9C Linear regression of experimental data for the continuous multi-analyte sensor depicted in .

[0104] Fig. 10A Schematic diagram showing a cross-sectional / side view of an in vivo portion of an analyte sensor as disclosed herein.

[0105] Fig. 10B is a perspective schematic diagram showing the in vivo portion of a continuous multi-analyte sensor as disclosed and described herein.

[0106] Fig. 10C Schematic side view showing an in vivo portion of a continuous multi-analyte sensor as disclosed and described herein.

[0107] Fig. 10D Schematic diagram showing a cross-sectional / side view of an in vivo portion of a continuous multi-analyte sensor as disclosed and described herein.

[0108] Fig.10E Schematic diagram showing a cross-section of an in vivo portion of a continuous multi-analyte sensor as disclosed and described herein.

[0109] Fig.10F Schematic side view showing an in vivo portion of a continuous multi-analyte sensor as disclosed and described herein.

[0110] Figure 10G Schematic side view showing an in vivo portion of a continuous multi-analyte sensor as disclosed and described herein.

[0111] Fig.11 For illustrating an exemplary continuous multi-analyte sensor membrane configuration as disclosed and described herein Fig. 10A Schematic diagram of a cross section (taken along line 11-11).

[0112] Fig. 12A is a perspective schematic diagram showing an in vivo portion of a continuous analyte sensor as disclosed and described herein.

[0113] Fig. 12B is a perspective schematic diagram showing an in vivo portion of a continuous analyte sensor as disclosed and described herein.

[0114] Fig.13A A perspective schematic diagram showing the in vivo portion of a continuous multi-electrode, multi-analyte sensor.

[0115] Fig. 13B for Fig.13A An enlarged perspective schematic diagram of the distal portion segment 13B of the sensor example shown in FIG.

[0116] Fig.14 Depicted is a basic schematic diagram of the operating principle of an amperometric enzymatic multi-analyte sensor as disclosed and described herein.

[0117] Fig.15 An illustration is provided to illustrate certain embodiments of an exemplary continuous multi-analyte sensor system in communication with at least one display device in accordance with various techniques as disclosed and described herein.

[0118] Fig.16 Depicted are exemplary experimental calibration data for a mediated continuous analyte sensor as disclosed and described herein.

[0119] Fig.17 Described herein as disclosed and described Fig.16 Example experimental drift data for a continuous analyte sensor.

[0120] Fig.18 Described herein as disclosed and described Fig.16 Exemplary experimental in vivo data of a continuous analyte sensor.

[0121] Fig.19 Depicted are exemplary experimental calibration data for a non-mediated continuous analyte sensor as disclosed and described herein.

[0122] Fig. 20 Described herein as disclosed and described Fig.19 Example experimental drift data for a continuous analyte sensor.

[0123] Fig.21A , Fig.21B and Fig. 21C An exemplary continuous ketone sensor configuration pathway as disclosed and described herein is depicted. DETAILED DESCRIPTION

[0124] A multi-analyte sensor designed for in vivo application is provided. Multi-analyte sensing can be used to help diagnose and / or monitor various health conditions, including chronic diseases. In some examples, the continuous multi-analyte sensor is configured to measure two or more analytes to achieve early intervention for adverse health conditions (including metabolic diseases) and to treat health conditions. Multi-analyte sensors have the following advantages: In some cases, a single analyte cannot provide enough information to make decisions about systemic health. By allowing more than one analyte to be sensed, the biological background of the body is measured more accurately. For example, glucose levels generally indicate a set of specific conditions that can be further improved using other analytes. Examples are DKA, metabolic function, insulin sensitivity and clearance, liver function, etc. Diabetic ketoacidosis (DKA) is the leading cause of mortality in individuals with type 1 diabetes under the age of 20. Over the past two decades, body-adorned continuous glucose monitors for assessing interstitial glucose levels have been commercially available. However, in some cases, such single analyte measurements alone may not be clinically sufficient to identify conditions such as euglycemic DKA, which has recently become a growing concern with the off-label use of SGLT-2 inhibitors in patients undergoing intensive insulin therapy.

[0125] The systems and methods discussed herein use multi-analyte sensing to provide feedback to patients and to provide feedback to healthcare providers regarding the health of their patients.

[0126] In one example, a single-wire electrode implementation is provided that supports amperometric measurements of multiple analytes.

[0127] In another example, a dual coaxial line electrode implementation is employed that supports amperometric measurement of two or more analytes according to the generalized n-dimensional Cottrell relation:

[0128]

[0129] where i is the current supported by the amperometric reaction, z is the valence or stoichiometry of the electrons participating in the reaction (e.g., 2 for hydrogen peroxide oxidation), F is the Faraday constant, A is the electrode redox active surface area, D is the diffusion coefficient of the redox species of interest (e.g., hydrogen peroxide), and C is b，0 is the total concentration of redox species at the electrode surface, R is the universal gas constant, T is the operating temperature (in K), is the applied overpotential in volts, t is the time measured from the initial application of the overpotential, and n is the dimension of the system (e.g., 1, 2, 3). For practical applications, in vivo analyte sensors tend to be highly diffusion limited, so that the controlling rate of reaction (and therefore current) is dominated by the mass diffusion rate of the redox species of interest. Due to the diffusion limitation imposed by the external resistance domain, amperometric sensors are designed to control the mass diffusion rate of the analyte of interest while attenuating (or enhancing) other co-circulating species.

[0130] In another example, the multi-analyte sensor device includes a transmitter configured to interact with the multi-analyte sensor. In one aspect, wireless transmission of data to a paired display device is provided so that multiple analytes can be evaluated in parallel.

[0131] The following description and figures illustrate examples of the present disclosure in detail. Those skilled in the art will recognize that the scope of the present disclosure encompasses many variations and modifications of the present disclosure. Therefore, the descriptive examples should not be considered to limit the scope of the present disclosure. In order to facilitate understanding of the examples disclosed herein, a number of terms are defined below.

[0132] The term "about" as used herein is a broad term and will be given its ordinary and customary meaning to those of ordinary skill in the art (and not limited to a special or customary meaning), and means (but is not limited to) allowing a certain degree of variability in values ​​or ranges, for example, within 10%, within 5%, or within 1% of the stated value or limit of the stated range, and including the exact stated value or range.

[0133] As used herein, the terms "adhere" and "attach" are broad terms and will be given their ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refer to (but are not limited to) holding, binding or sticking, such as by adhesion, bonding, grasping, interpenetration or fusion.

[0134] As used herein, the term "analyte" is a broad term and will be given its ordinary and customary meaning to those of ordinary skill in the art (and is not limited to a special or customized meaning), and refers to (but is not limited to) a substance or chemical component that can be analyzed in a biological fluid (e.g., blood, interstitial fluid, cerebrospinal fluid, lymph, urine, sweat, saliva, etc.). Analytes can include naturally occurring substances, artificial substances, metabolites, and / or reaction products. In some examples, the analyte measured by the sensing region, sensing device, and sensing method is glucose. However, other analytes are also contemplated, including but not limited to carboxyprothrombin; acylcarnitines; adenine phosphoribosyltransferase; adenosine deaminase; albumin; alpha-fetoprotein; amino acid profile (arginine (Krebs cycle), histidine / urocanic acid, homocysteine, phenylalanine / tyrosine, tryptophan); androstenedione; antipyrine; arabinitol enantiomers; arginase; benzoylecgonine (cocaine); bilirubin, biotinidase; biopterin; c-reactive protein; carnitine; carnosinase; CD4; ceruloplasmin; chenodeoxycholic acid; chloroquine; cholesterol; cholinesterase; conjugated 1-beta hydroxy -cholic acid; cortisol; creatine; creatine kinase; creatine kinase MM isozyme; creatinine; cyclosporin A; d-penicillamine; desethylchloroquine; dehydroepiandrosterone sulfate; DNA (acetylase polymorphism, alcohol dehydrogenase, alpha 1-antitrypsin, cystic fibrosis, Duchenne dystrophy / Becker muscular dystrophy, glucose-6-phosphate dehydrogenase, hemoglobin A, hemoglobin S, hemoglobin C, hemoglobin D, hemoglobin E, hemoglobin F, D-Punjab, beta-thalassemia, hepatitis B virus, HCMV, HIV-1, HTLV-1, Leber hereditary optic neuropathy, MC AD, RNA, PKU, Plasmodium vivax, 21-deoxycortisol); desbutyl halofantrine; dihydropteridine reductase; diphtheria / tetanus antitoxin; erythrocyte arginase; erythrocyte protoporphyrin; esterase D; fatty acids / acylglycines; free β-human chorionic gonadotropin; free erythrocyte porphyrin; free thyroxine (FT4); free triiodothyronine (FT3); fumaryl acetoacetase; galactose / gal-1-phosphate; galactose-1-phosphate uridyltransferase; gentamicin; glucose-6-phosphate dehydrogenase; glutathione; glutathione peroxidase; glycerol; glycerol aminocholic acid; glycosylated hemoglobin; halofantrine; hemoglobin variants; hexosaminidase A; human erythrocyte carbonic anhydrase I; 17-alpha-hydroxyprogesterone; hypoxanthine phosphoribosyltransferase; immunoreactive trypsin; beta-hydroxybutyrate; ketones; lactate; lead; lipoprotein ((a), B / A-1, beta); lysozyme; mefloquine; netilmicin; oxygen; phenobarbital; phenytoin; phytanic acid / pristanic acid; potassium, sodium and / or other blood electrolytes; progesterone; prolactin; prolinase; purine nucleoside phosphorylase; quinine; reverse triiodothyronine (rT3); selenium; serum pancreatic lipase; sisomicin;Somatomedin C; specific antibodies (adenovirus, antinuclear antibody, anti-zeta antibody, arbovirus, Aujeszky's disease virus, dengue virus, Guinea worm, Echinococcus granulosus, Entamoeba histolytica, enterovirus, Giardia, Helicobacter pylori, hepatitis B virus, herpes virus, HIV-1, IgE (atopic disease), influenza virus, Leishmania donovani, Leptospira, measles / mumps / rubella, Mycobacterium leprae, Mycoplasma pneumoniae, myoglobin, Onchocerca volvulus, parainfluenza virus, Plasmodium falciparum, polio virus, Pseudomonas aeruginosa, Respiratory syncytial virus, Rickettsia (tsutsugamushi), Schistosoma mansoni, Toxoplasma gondii, Treponema pallidum, Trypanosoma cruzi / T. lamblia, Vesicular stoma virus, Wuchereria bancrofti, Yellow fever virus); specific antigens (Hepatitis B virus, HIV-1); succinylacetone; sulfadoxine; theophylline; thyroid stimulating hormone (TSH); thyroxine (T4); thyroxine binding globulin; trace elements; transferrin; UDP-galactose-4-epimerase; urea; uric acid; uroporphyrinogen I synthase; vitamin A; white blood cells; and zinc protoporphyrin. In some examples, salts, sugars, proteins, fats, vitamins, and hormones naturally present in blood or interstitial fluids may also constitute analytes. Analytes may be naturally present in biological fluids or may be endogenous, such as metabolites, hormones, antigens, antibodies, etc. Alternatively, the analyte may be introduced into the body or be exogenous, such as contrast agents for imaging, radioisotopes, chemical agents, fluorocarbon-based synthetic blood, or drugs or drug compositions, including but not limited to insulin; ethanol; cannabis (marijuana, tetrahydrocannabinol, hashish); inhalants (nitrous oxide, amyl nitrite, butyl nitrite, chlorinated hydrocarbons, hydrocarbons); cocaine (crack cocaine); stimulants (amphetamine, methamphetamine, ); sedatives (barbiturates, methaqualone, tranquilizers such as ); Hallucinogens (phencyclidine, lysergic acid, mescaline, pyodate, psilocybin); Anesthetics (heroin, codeine, morphine, opium, pethidine, Fentanyl, ); designer drugs (fentanyl, pethidine, amphetamine, methamphetamine, and analogs of phencyclidine, e.g., ecstasy); anabolic steroids; and nicotine. Metabolites of drugs and drug compositions are also contemplated analytes. Analytes produced in the body such as neurochemicals and other chemicals, e.g., ascorbic acid, uric acid, dopamine, norepinephrine, 3-methoxytyramine (3MT), 3,4-dihydroxyphenylacetic acid, may also be analyzed. Homovanillic acid (HVA), 5-hydroxytryptamine (5HT) and 5-hydroxyindoleacetic acid (FHIAA) and histamine.

[0135] As used herein, the phrases "analyte measuring device," "analyte monitoring device," "analyte sensing device," and / or "multi-analyte sensor device" are broad phrases and will be given their ordinary and customary meanings (and not limited to special or customized meanings) to one of ordinary skill in the art, and refer to (but are not limited to) devices and / or systems responsible for detecting or transducing signals associated with a particular analyte or combination of analytes. For example, these phrases may refer to (but are not limited to) an instrument responsible for detecting a particular analyte or combination of analytes. In one example, the instrument includes a sensor coupled to a circuit disposed within a housing and configured to process signals associated with analyte concentrations into information. In one example, such a device and / or system is capable of providing specific quantitative, semi-quantitative, qualitative, and / or semi-qualitative analytical information using a biorecognition element in combination with a transduction (detection) element.

[0136] As used herein, the term "amphiphilic" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customary meaning) and refers to, but is not limited to, chemical compounds or polymers that have both hydrophilic and hydrophobic segments or properties.

[0137] As used herein, the terms "biosensor" and / or "sensor" are broad terms and will be given their ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refer to (but not limited to) a portion of an analyte measuring device, an analyte monitoring device, an analyte sensing device, and / or a multi-analyte sensor device that is responsible for detecting or transducing a signal associated with a specific analyte or combination of analytes. In one example, a biosensor or sensor generally includes a body, a working electrode, a reference electrode, and / or a counter electrode that are coupled to the body and form a surface configured to provide a signal during an electrochemical reaction. One or more membranes may be affixed to the body and cover the electrochemical reaction surface. In one example, such a biosensor and / or sensor is capable of providing a specific quantitative, semi-quantitative, qualitative, or semi-qualitative analytical signal using a biorecognition element combined with a transduction (detection) element.

[0138] As used herein, the phrases "sensing moiety", "sensing membrane" and / or "sensing mechanism" are broad phrases and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) a portion of a biosensor and / or sensor that is responsible for detecting or transducing a signal associated with a specific analyte or combination of analytes. In one example, the sensing moiety, sensing membrane and / or sensing mechanism typically includes an electrode that is configured to provide a signal during an electrochemical reaction with one or more membranes covering an electrochemical reaction surface. In one example, such a sensing moiety, sensing membrane and / or sensing mechanism can use a biorecognition element combined with a transduction (detection) element to provide a specific quantitative, semi-quantitative, qualitative, semi-qualitative analytical signal.

[0139] As used herein, the term "substantially" refers to a majority or majority, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

[0140] As used herein, the phrase "substantially free" can mean having no or insignificant amounts of a material such that the amount of material present does not affect the material properties of the composition including the material, such that the material comprises from about 0% to about 5% by weight, or from about 0% to about 1% by weight, or about 5% by weight or less, or less than or equal to about 4.5%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01 or about 0.001% by weight or less, or about 0% by weight of the composition.

[0141] As used herein, the terms "adhere" and "attach" are broad terms and will be given their ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refer to, but are not limited to, holding, binding or sticking, for example, by adhesion, bonding, grasping, interpenetration or fusion.

[0142] As used herein, the phrase "barrier cell layer" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) the part of the foreign body response that forms an adherent monolayer of cells (e.g., macrophages and foreign body giant cells) that substantially blocks the transport of molecules and other substances to the implantable device.

[0143] As used herein, the term "biologically active agent" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) any substance that has an effect on living tissue or elicits a response from living tissue.

[0144] The phrases "biointerface membrane" and "biointerface layer" as used interchangeably herein are broad phrases and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customary meanings), and refer to (but are not limited to) a permeable membrane (which may include multiple domains) or layer that acts as a bioprotective interface between a recipient tissue and an implantable device. The terms "biointerface" and "bioprotective" are used interchangeably herein.

[0145] As used herein, the term "biostable" is a broad term and is to be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customary meaning), and refers to (but is not limited to) materials that are relatively resistant to degradation by processes encountered in the body.

[0146] As used herein, the phrase "cellular process" is a broad term and is to be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customary meaning), and refers to, but is not limited to, cytopodia.

[0147] As used herein, the phrase "cell attachment" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) the adhesion of cells and / or cellular processes to a material at the molecular level, and / or the attachment of cells and / or cellular processes to the surface of a microporous material or a macroporous material. An example of a material used in the prior art to promote cell attachment to its porous surface is BIOPORE® sold by Millipore (Bedford, Mass.). TM Cell culture supports and as described in U.S. Pat. No. 5,741,330 to Brauker et al.

[0148] As used herein, the term "cofactor" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) one or more substances whose presence contributes to or is necessary for the analyte-related activity of an enzyme. The analyte-related activity may include, but is not limited to, any one or a combination of binding, electron transfer, and chemical transformation. Cofactors include coenzymes, non-protein compounds, metal ions, and / or metal-organic complexes. Coenzymes include prosthetic groups and cosubstrates.

[0149] As used herein, the term "continuous" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) an uninterrupted or continuous portion, domain, coating or layer.

[0150] As used herein, the phrases "continuous analyte sensing" and "continuous multi-analyte sensing" are broad terms and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) a period of time during which monitoring of analyte concentration is performed continuously, continuously, and / or intermittently (but regularly) (e.g., from about every second or less to about once a week or more). In other examples, from about every 2 seconds, 3 seconds, 5 seconds, 7 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, or 60 seconds to about 1.25 minutes, 1.50 minutes, 1.75 minutes, 2.00 minutes, 2.25 minutes, 2.50 minutes, 2.75 minutes, 3.00 minutes, 3.25 minutes, 3.50 minutes, 3.75 minutes, 4.00 minutes, 4.25 minutes, 4.50 minutes, Analyte concentration monitoring is performed once every 10 minutes, 20 minutes, 30 minutes, 40 minutes or 50 minutes to about every 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours. In another example, the monitoring of analyte concentration is performed once every 8 hours to about every 12 hours, 16 hours, 20 hours or 24 hours. In another example, the monitoring of analyte concentration is performed about every day to about every 1.5 days, 2 days, 3 days, 4 days, 5 days, 6 days or 7 days. In another example, the monitoring of analyte concentration is performed about every week to about every 1.5 weeks, 2 weeks, 3 weeks or more weeks.

[0151] As used herein, the term "coaxial" should be broadly interpreted to include sensor architectures having elements aligned along a shared axis around a core, which may be configured to have a circular, elliptical, triangular, polygonal, or other cross-section, such elements may include electrodes, insulating layers, or other elements that may be positioned circumferentially around the core layer, such as a core electrode or a core polymer wire.

[0152] As used herein, the term "coupled" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) two or more system elements or components being configured to be at least one of electronically attached, mechanically attached, thermally attached, operably attached, chemically attached, or otherwise attached. For example, if one element is covalently connected, communicatively connected, electrostatically connected, thermally connected, mechanically connected, magnetically connected, or ionically associated with another element, or is physically trapped, adsorbed, or absorbed by another element, the element is "coupled." Similarly, the phrases "operably connected," "operably linked," and "operably coupled," as used herein, may refer to one or more components being attached to another component in a manner that facilitates the transmission of at least one signal between the components. In some examples, the components are part of the same structure and / or are integrated with each other, such as being covalently, electrostatically, mechanically, thermally, magnetically, ionically associated, or physically entrapped or absorbed (i.e., "directly coupled," such as without intervening elements). In other examples, the components are connected via a remote device. For example, one or more electrodes can be used to detect an analyte in a sample and convert that information into a signal; the signal can then be transmitted to a circuit. In this example, the electrodes are "operably linked" to an electronic circuit. As used herein, the phrase "removably coupled" may refer to two or more system elements or components that are configured or have been electronically, mechanically, thermally, operably, chemically, or otherwise attached and are separated without damaging any of the coupled elements or components. As used herein, the phrase "permanently coupled" may refer to two or more system elements or components that are configured or have been electrically, mechanically, thermally, operably, chemically, or otherwise attached, but cannot be decoupled without damaging at least one of the coupled elements or components.

[0153] As used herein, the term "defined edge" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) a distinct edge or boundary between layers, domains, coatings, or portions. A "defined edge" is in contrast to a gradual transition between layers, domains, coatings, or portions.

[0154] As used herein, the term "discontinuous" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) a discontinuous, intermittent or separated portion, layer, coating or domain.

[0155] As used herein, the term "distal" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) an area that is relatively far away from a reference point (such as a starting point or attachment point).

[0156] As used herein, the term "domain" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) a region of a membrane system, which can be a layer, a uniform or non-uniform gradient (e.g., an anisotropic region of a membrane), or a portion of a membrane capable of sensing one, two or more analytes. The domains discussed herein can be formed as a single layer, two or more layers, a bilayer pair, or a combination thereof.

[0157] As used herein, the term "drift" is a broad term and will be given its ordinary and customary meaning (and not limited to a special or customized meaning) to those of ordinary skill in the art, and refers to (but not limited to) a progressive increase or decrease in the signal over time that is unrelated to changes in the recipient system analyte concentration (e.g., recipient postprandial glucose concentration). Although not wishing to be bound by theory, it is believed that drift may be the result of a local reduction in the transport of glucose to the sensor, for example, due to the formation of a foreign body capsule (FBC), or due to an insufficient amount of interstitial fluid surrounding the sensor, which results in a reduction in the transport of oxygen and / or glucose to the sensor. In one example, an increase in local interstitial fluid can slow or reduce drift and thus improve sensor performance. Drift can also be the result of sensor electronics or an algorithmic model for compensating for noise or other anomalies that can occur with electrical signals in, for example, the picoampere range, femtoampere range, nanoampere range, microampere range, milliampere range, ampere range, etc.

[0158] The phrases "drug release membrane" and "drug release layer" as used interchangeably herein are broad phrases, and each will be given its ordinary and customary meaning (and not limited to a special or customized meaning) to those of ordinary skill in the art, and refer to (but not limited to) a permeable membrane or semipermeable membrane that is permeable to one or more bioactive agents. In one example, the "drug release membrane" and "drug release layer" typically have a thickness of several microns or more and are composed of two or more domains. In one example, the drug release layer and / or the drug release membrane are substantially the same as the biointerface layer and / or the biointerface membrane. In another example, the drug release layer and / or the drug release membrane are different from the biointerface layer and / or the biointerface membrane.

[0159] As used herein, the term "electrochemical reaction surface" is a broad term and will be given its ordinary and customary meaning to those of ordinary skill in the art (and is not limited to a special or customized meaning), and refers to (but is not limited to) the surface of an electrode where an electrochemical reaction occurs. In one example, the reaction is a Faradaic reaction and results in a charge transfer between the surface and its environment. In one example, hydrogen peroxide produced by an enzyme-catalyzed reaction in which the analyte is oxidized on the surface results in a measurable electron flow. For example, in the detection of glucose, glucose oxidase produces hydrogen peroxide (H2O2) as a byproduct. H2O2 reacts with the surface of the working electrode to produce two protons (2H + ), two electrons (2e - ) and an oxygen molecule (O2), thereby generating the detected electron flow. In the counter electrode, the reducible species (such as O2) is reduced on the electrode surface to balance the current generated by the working electrode.

[0160] As used herein, the term "electrolysis" is a broad term and is to be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customized meaning), and refers to (but is not limited to) the direct or indirect electro-oxidation or electro-reduction (collectively "redox") of a compound by one or more enzymes, cofactors or mediators.

[0161] As used herein, the phrase "hard segment" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customary meaning), and refers to (but is not limited to) an element of a copolymer, such as a polyurethane, polycarbonate polyurethane, or polyurethane urea copolymer, which imparts resistance properties, such as resistance to bending or twisting. The phrase "hard segment" can be further characterized as a crystalline, semi-crystalline, or glassy material having a glass transition temperature ("Tg") generally above ambient temperature as determined by dynamic scanning calorimetry. Exemplary hard segment elements for preparing polycarbonate polyurethane or polyurethane urea hard segments include norbornane diisocyanate (NBDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), 1,3-phenylene diisocyanate (MPDI), trans-1,3-bis(isocyanatomethyl)cyclohexane (1,3-H6XDI), dicyclohexylmethane-4,4′-diisocyanate (HMDI), 4,4′-diphenylmethane diisocyanate (MDI), trans-1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6XDI), 1,4-cyclohexyl diisocyanate (CHDI), 1,4-phenylene diisocyanate (PPDI), 3,3′-dimethyl-4,4′-biphenyl diisocyanate (TODI), 1,6-hexamethylene diisocyanate (HDI), or combinations thereof.

[0162] As used herein, the term "recipient" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customary meaning), and refers to (but is not limited to) a mammal, such as a human.

[0163] As used herein, the terms "indwelling", "embedded", "implanted" or "implantable" are broad terms and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) an object including a sensor that is inserted or configured to be inserted in the following manner: subcutaneous insertion (i.e., in the fat layer between the skin and the muscle), intradermal insertion (i.e., penetrating the stratum corneum and positioned in the epidermis or dermis layer of the skin), or percutaneous insertion (i.e., penetrating, entering or passing through the intact skin), which may result in the sensor having an in vivo portion and an extracorporeal portion. The term "indwelling" also encompasses an object configured to be inserted subcutaneously, intradermally or percutaneously, whether or not it has been so inserted.

[0164] As used herein, the phrase "insertable surface area" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) the surface area of ​​the insertable portion of the analyte sensor, including but not limited to geometric surface areas in analyte sensors as described herein, such as planar, flat or substantially planar and / or coaxial with a substrate.

[0165] As used herein, the phrase "insertable volume" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or custom meaning), and refers to (but is not limited to) the volume in front of and beside the insertion path of the insertable portion of the analyte sensor as described herein, and the incision made in the skin for inserting the insertable portion of the analyte sensor. The insertable volume also includes up to 5 mm radially or perpendicular to the volume in front of and beside the insertion path.

[0166] As used herein, the terms "interferor" and "interfering substance" are broad terms and will be given their ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refer to (but are not limited to) effects and / or substances that interfere with the measurement of an analyte of interest in a sensor to produce a signal that inaccurately represents the analyte measurement. In one example of an electrochemical sensor, an interfering substance is a compound that produces a non-analyte-specific signal due to a reaction on an electrochemically active surface.

[0167] As used herein, the term "in vivo" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and includes (but is not limited to) parts of a device (e.g., a sensor) that are suitable for insertion into and / or presence within a recipient's living body.

[0168] As used herein, the term "ex vivo" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and includes (but is not limited to) parts of a device (e.g., a sensor) that are adapted to remain and / or exist outside the living body of a recipient.

[0169] As used herein, the terms "machine storage medium", "device storage medium", "computer storage medium" (collectively "machine storage medium") mean the same thing and may be used interchangeably in this disclosure. The terms refer to a single or multiple storage devices and / or media (e.g., centralized or distributed databases, and / or associated caches and servers) that store executable instructions and / or data, as well as cloud-based storage systems or storage networks that include multiple storage devices or devices. Thus, these terms shall include, but are not limited to, solid-state memory and optical and magnetic media, including memory internal or external to the processor. Specific examples of machine storage media, computer storage media, and / or device storage media include nonvolatile memory, including, for example, semiconductor memory devices such as erasable programmable read-only memories (EPROMs), electrically erasable programmable devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The terms machine storage medium, computer storage medium, and device storage medium specifically exclude carrier waves, modulated data signals, and other such media, at least some of which are covered under the term "signal media" discussed below.

[0170] As used herein, the terms and phrases "mediator" and "redox mediator" are broad terms and phrases and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) any compound or collection of compounds that can directly or indirectly transfer electrons between an analyte, analyte precursor, analyte surrogate, analyte reduction or analyte oxidation enzyme or cofactor and an electrode surface maintained at a certain potential. In one example, the mediator accepts electrons from one or more enzymes or cofactors or transfers electrons to one or more enzymes or cofactors, and / or exchanges electrons with a sensor system electrode. In one example, the mediator is a transition metal-coordinated organic molecule capable of reversible oxidation and reduction reactions. In other examples, the mediator can be an organic molecule or metal capable of reversible oxidation and reduction reactions.

[0171] As used herein, the term "membrane" is a broad term and will be given its ordinary and customary meaning to those of ordinary skill in the art (and not limited to a special or custom meaning), and refers to (but not limited to) a structure configured to perform the following functions, including but not limited to: protection of exposed electrode surfaces from biological environments, diffusion resistance (restriction) of analytes, acting as a matrix for catalysts (e.g., one or more enzymes) that enable enzymatic reactions, limiting or blocking interfering substances, providing hydrophilicity at the electrochemical reaction surface of the sensor interface, acting as an interface between recipient tissue and an implantable device, regulating recipient tissue response via drug (or other substance) release, and combinations thereof. When used herein, the terms "membrane" and "matrix" are intended to be used interchangeably.

[0172] As used herein, the phrase "membrane system" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) a permeable or semipermeable membrane that may be composed of two or more domains, two or more layers, or two or more layers within a domain and is typically composed of a material of a few microns or more thickness, which is permeable to oxygen and optionally permeable to, for example, glucose or another analyte. In one example, the membrane system includes an enzyme that enables an analyte reaction to occur, whereby the concentration of the analyte can be measured.

[0173] The phrases "machine-readable medium," "computer-readable medium," and "device-readable medium" mean the same thing and are used interchangeably in this disclosure. The phrase includes machine storage media and signal media operatively coupled to a sensor, biosensor, analyte sensing device, or analyte monitoring device. Thus, the phrase includes storage devices / media and carrier / modulated data signals operatively coupled to a sensor, biosensor, analyte sensing device, or analyte monitoring device.

[0174] As used herein, the term "micro" is a broad term and will be given its ordinary and customary meaning to persons of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) approximately 10 microns in diameter that is not visible without magnification. -6 The term "micro" is the opposite of the term "large," which refers to large objects that are visible without magnification. Similarly, the term "nano" refers to objects of approximately 10 -9 m small object or scale.

[0175] As used herein, the term "noise" is a broad term and is used in its ordinary sense, including but not limited to signals detected by the sensor or sensor electronics that are unrelated to the analyte concentration and may cause reduced sensor performance. One type of noise has been observed during a few hours (e.g., about 2 hours to about 24 hours) after the sensor is inserted. After the first 24 hours, the noise may disappear or decrease, but in some hosts, the noise may last for about three to four days. In some cases, predictive modeling, artificial intelligence and / or algorithmic means can be used to reduce the noise. In other cases, the noise can be reduced by, for example, using a drug release layer with at least one bioactive agent to address immune response factors associated with the presence of the implanted sensor. For example, the noise of one or more exemplary biosensors disclosed in the present invention can be determined and then qualitatively or quantitatively compared. For example, a raw signal time series with a fixed sampling interval (in pA) is obtained, and a smoothed version of the raw signal time series can be obtained, for example, by applying a third-order low-pass digital Chebyshev II filter. Other smoothing algorithms can be used. At each sampling interval, the absolute difference in pA can be calculated to provide a smoothed time series. The smoothed time series can be converted to units of mg / dL (units of "noise") using a glucose sensitivity time series in units of pA / mg / dL, which is derived using a mathematical model between the raw signal and a reference blood glucose measurement (e.g., obtained from a blood glucose meter). Optionally, the time series can be aggregated as desired, such as by hour or day. Comparison of corresponding time series between different exemplary biosensors having a drug release layer disclosed herein and one or more bioactive agents provides a qualitative or quantitative determination of noise improvement.

[0176] As used herein, the terms "optional" or "optionally" are broad terms, and will be given their ordinary and customary meaning to those skilled in the art (and not limited to a special or customary meaning), and mean (but not limited to) that the subsequently described event or circumstance can occur or not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not occur.

[0177] As used herein, the term "plane" is to be broadly interpreted as describing a sensor architecture having a substrate including at least a first surface and an opposing second surface, and, for example, including a plurality of elements arranged on one or more surfaces or edges of the substrate. The plurality of elements may include conductive or insulating layers or elements configured to operate as a circuit. The plurality of elements may or may not be electrically or otherwise coupled. In one example, the plane includes one or more edges separating the opposing surfaces.

[0178] As used herein, the term "proximal" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refers to (but is not limited to) the spatial relationship between various elements compared to a specific reference point. For example, some examples of devices include a membrane system having a biological interface layer and an enzyme domain or layer. If a sensor is considered to be a reference point and the enzyme domain is positioned closer to the sensor than the biological interface layer, then the enzyme domain is closer to the sensor than the biological interface layer.

[0179] As used herein, the phrases and terms "processor module" and "microprocessor" are each broad phrases and terms and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) a computer system, state machine, processor, etc. designed to perform arithmetic or logical operations using logic circuits that respond to and process the basic instructions that drive the computer.

[0180] As used herein, the term "semi-continuous" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) a portion, coating, domain or layer that includes one or more continuous and non-continuous portions, coatings, domains or layers. For example, a coating that is disposed around a sensing area but not about the sensing area is "semi-continuous".

[0181] As used herein, the phrases "sensing moiety", "sensing membrane" and / or "sensing mechanism" are broad phrases and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) a portion of a biosensor and / or sensor that is responsible for detecting or transducing a signal associated with a specific analyte or combination of analytes. In one example, the sensing moiety, sensing membrane and / or sensing mechanism typically includes an electrode that is configured to provide a signal during an electrochemical reaction with one or more membranes covering an electrochemical reaction surface. In one example, such a sensing moiety, sensing membrane and / or sensing mechanism is capable of providing a specific quantitative, semi-quantitative, qualitative, semi-qualitative analytical signal using a biorecognition element combined with a transduction and / or detection element.

[0182] During the general operation of the analyte measuring device, biosensor, sensor, sensing region, sensing portion or sensing mechanism, a biological sample (e.g., blood or interstitial fluid) or a component thereof is contacted with an enzyme (e.g., glucose oxidase), DNA, RNA or protein or aptamer (e.g., one or more periplasmic binding proteins (PBPs) or mutants or fusion proteins thereof having one or more analyte binding regions, each region being capable of specifically or reversibly binding to and / or reacting with at least one analyte) directly or after passing through one or more membranes. The interaction of the biological sample or a component thereof with the analyte measuring device, biosensor, sensor, sensing region, sensing portion or sensing mechanism results in signal transduction, which allows for qualitative, semi-qualitative, quantitative or semi-quantitative determination of the level of an analyte in the biological sample, such as glucose, ketones, lactate, potassium, etc.

[0183] In one example, the sensing region or sensing portion may include at least a portion of a conductive substrate or at least a portion of a conductive surface (e.g., a wire (coaxial) or a conductive trace or a substantially planar substrate comprising a substantially planar trace) and a membrane. In one example, the sensing region or sensing portion may include a non-conductive body; a working electrode, a reference electrode, and a counter electrode (optional) that form an electrochemically reactive surface at one location on the body and form an electronic connection at another location on the body; and a sensing film attached to the body and covering the electrochemically reactive surface. In some examples, the sensing film also includes an enzyme domain (e.g., an enzyme domain) and an electrolyte phase (e.g., a free-flowing liquid phase comprising an electrolyte-containing fluid described further below). These terms are broad enough to include the entire device or just its sensing portion (or something in between).

[0184] In another example, the sensing region may include one or more periplasmic binding proteins (PBPs) (including mutants or fusion proteins thereof), or an aptamer having one or more analyte binding regions, each region being capable of specifically and reversibly binding at least one analyte. Changes in the aptamer or mutations in the PBP may contribute to or alter one or more binding constants, long-term protein stability (including thermal stability), to bind the protein to a specific encapsulating matrix, membrane or polymer, or to attach a detectable reporter group or "label" to indicate changes in the binding region or transduce a signal corresponding to one or more analytes present in the biological fluid. Specific examples of changes in the binding region include, but are not limited to, changes in the hydrophobic / hydrophilic environment, changes in three-dimensional conformation, changes in the orientation of amino acids / nucleic acid side chains in the protein binding region, and the redox state of the binding region. Such changes in the binding region provide for the transduction of a detectable signal corresponding to one or more analytes present in the biological fluid.

[0185] In one example, the sensing region determines the selectivity between one or more analytes so that only the analytes that must be measured produce (transduce) a detectable signal. The selection can be based on any chemical or physical recognition of the analyte by the sensing region, wherein the chemical composition of the analyte is not changed, or wherein the sensing region causes or catalyzes a reaction of the analyte that changes the chemical composition of the analyte.

[0186] As used herein, the term "sensitivity" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) the amount of signal (e.g., in the form of current and / or voltage) generated by a predetermined amount (unit) of measured analyte. For example, in one example, for each 1 mg / dL of analyte, the sensor has a sensitivity (or slope) of about 1 picoampere to about 100 picoamperes of current.

[0187] The phrase "signal medium" or "transmission medium" should be taken to include any form of modulated data signal, carrier wave, etc. The phrase "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal.

[0188] As used herein, the phrases and terms "small diameter sensor", "small structure sensor" and "microsensor" are broad phrases and terms and will be given their ordinary and customary meanings to those of ordinary skill in the art (and are not limited to special or customized meanings), and refer to (but are not limited to) sensing mechanisms that are less than about 2 mm in at least one dimension. In other examples, the sensing mechanism is less than about 1 mm in at least one dimension. In some examples, the sensing mechanism (sensor) is less than about 0.95 mm, 0.9 mm, 0.85 mm, 0.8 mm, 0.75 mm, 0.7 mm, 0.65 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm. In some examples, the largest dimension of the independently measured length, width, diameter, thickness, or circumference of the sensing mechanism does not exceed about 2 mm. In some examples, the sensing mechanism is a coaxial sensor, wherein the diameter of the sensor is less than about 1 mm, see, e.g., U.S. Pat. No. 6,613,379 to Ward et al. and U.S. Pat. No. 7,497,827 to Brister et al., both of which are incorporated herein by reference in their entirety. In some alternative examples, the sensing mechanism includes an electrode deposited on a planar or substantially planar substrate, wherein the thickness of the implantable portion is less than about 1 mm, see, e.g., U.S. Pat. No. 6,175,752 to Say et al. and U.S. Pat. No. 5,779,665 to Mastrototaro et al., both of which are incorporated herein by reference in their entirety.

[0189] As used herein, the phrase "soft segment" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) an element of a copolymer, such as a polyurethane, polycarbonate polyurethane, or polyurethane urea copolymer, which imparts flexibility to the chain. The phrase "soft segment" can also be characterized as an amorphous material with a low Tg (e.g., a Tg that is generally no higher than ambient temperature or normal mammalian body temperature).

[0190] As used herein, the phrase "solid portion" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customary meaning), and refers to (but is not limited to) a portion of a membrane material that has a mechanical structure that defines a cavity, void, or other non-solid portion.

[0191] As used herein, the term "transduction" and their grammatical equivalents are broad terms and will be given their ordinary and customary meaning to one of ordinary skill in the art (and not limited to a special or customized meaning), and refer to (but not limited to) optical, electrical, electrochemical, acoustic / mechanical or colorimetric techniques and methods. Electrochemical properties include current and / or voltage, inductance, capacitance, impedance, transconductance, and potential. Optical properties include absorbance, fluorescence / phosphorescence, fluorescence / phosphorescence decay rate, wavelength shift, two-wave phase modulation, bio / chemiluminescence, reflectivity, light scattering, and refractive index. For example, the sensing region transduces recognition of an analyte into a semi-quantitative or quantitative signal.

[0192] As used herein, the phrase "transduction element" is a broad phrase and will be given its ordinary and customary meaning to one of ordinary skill in the art (and is not limited to a special or customized meaning), and refers to (but is not limited to) an analyte recognition portion that is capable of directly or indirectly promoting the transduction of a detectable signal corresponding to the presence and / or concentration of the recognized analyte. In one example, the transduction element is one or more enzymes, one or more aptamers, one or more ionophores, one or more capture antibodies, one or more proteins, one or more biological cells, one or more oligonucleotides and / or one or more DNA or RNA moieties. The transcutaneous continuous multi-analyte sensor can be used in vivo for various lengths of time. The continuous multi-analyte sensor system discussed herein can be a transcutaneous device in that a portion of the device can be inserted through the recipient's skin and into the underlying soft tissue, while a portion of the device remains on the surface of the recipient's skin. In one aspect, in order to overcome problems associated with noise or other sensor functions in the short term, an example employs a material that promotes the formation of a fluid pocket around the sensor, such as a porous biointerface membrane or matrix that creates a space between the sensor and the surrounding tissue. In some examples, the sensor is provided with a spacer adapted to provide a fluid pocket between the sensor and the recipient tissue. It is believed that the spacer (eg, a biointerface material, matrix, structure, etc., as described in greater detail elsewhere herein) transports oxygen and / or glucose to the sensor.

[0193] Membrane system

[0194] The membrane system disclosed herein is suitable for use in implantable devices in contact with biological fluids. For example, the membrane system can be used with an implantable device (such as a device for monitoring and determining the level of analytes in biological fluids, such as a device for monitoring the glucose level of individuals with diabetes). In some examples, the analyte measuring device is a continuous device. The analyte measuring device can use any suitable sensing element to provide a raw signal, including but not limited to sensing elements involving enzyme elements, chemical elements, physical elements, electrochemical elements, spectrophotometric measuring elements, current measuring elements, potential measuring elements, polarization measuring elements, thermal measuring elements, radiation measuring elements, immunochemical elements, etc.

[0195] Suitable membrane systems for use in the foregoing multi-analyte systems and devices may include, for example, membrane systems disclosed in US Pat. No. 6,015,572, US Pat. No. 5,964,745, and US Pat. No. 6,083,523, the entire contents of which are incorporated herein by reference for their teachings of membrane systems.

[0196] Typically, the membrane system includes multiple domains, such as an electrode domain, an interference domain, an enzyme domain, a resistor domain, and a biointerface domain. The membrane system can be deposited on an exposed electroactive surface using known thin film techniques (e.g., vapor deposition, spraying, electrodeposition, dipping, brushing, film coating, drop coating, etc.). Additional steps can be applied after the deposition of the membrane material, such as drying, annealing, and curing (e.g., UV curing, thermal curing, wet curing, radiation curing, etc.) to enhance certain properties, such as mechanical properties, signal stability, and selectivity. In a typical process, after depositing the resistor domain film, a "dry film" thickness of about 0.05 microns (μm) or less to about 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or 16 μm of biointerface / drug release layer is formed. "Dry film" thickness refers to the thickness of a cured film cast from a coating formulation by standard coating techniques.

[0197] In some examples, the biointerface / drug release layer is formed by a biointerface polymer, wherein the biointerface polymer includes one or more membrane domains and one or more zwitterionic repeating units, and the membrane domain includes a polyurethane and / or polyurea segment. In some examples, the biointerface / drug release layer coating is formed by a polyurethane urea in which a carboxybetaine group is combined in a polymer and a non-ionic hydrophilic polyethylene oxide segment, wherein the polyurethane urea polymer is dissolved in an organic or non-organic solvent system according to a predetermined coating formulation, and cross-linked with an isocyanate cross-linker and cured at a moderate temperature of about 50°C. The solvent system can be a single solvent or a solvent mixture to help dissolve or disperse the polymer. The solvent can be a solvent selected as a polymerization medium or added after the polymerization is completed. The solvent is selected from solvents with lower boiling points to promote drying and have lower toxicity for implant applications. Examples of these solvents include aliphatic ketones, esters, ethers, alcohols, hydrocarbons, etc. Depending on the final thickness and solution viscosity of the biointerface / drug release layer (related to the percentage of polymer solids), the coating can be applied in a single step or multiple repeated steps (such as dipping) of the selected process to build the desired thickness. In yet other examples, the bioprotective polymer is formed from a polyurethaneurea incorporating carboxylic acid groups and carboxybetaine groups in the polymer and a nonionic hydrophilic polyethylene oxide segment, wherein the polyurethaneurea polymer is dissolved in an organic or non-organic solvent system in the coating formulation and cross-linked with a carbodiimide (e.g., 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) or a polycarbodiimide cross-linker) and cured at a moderate temperature of about 50° C. In one example, a polycarbodiimide cross-linker is used.

[0198] In other examples, the biointerface / drug release layer coating is formed by a polyurethane urea in which sulfobetaine groups are incorporated into the polymer and a non-ionic hydrophilic polyethylene oxide segment, wherein the polyurethane urea polymer is dissolved in an organic or non-organic solvent system according to a predetermined coating formulation, and cross-linked with an isocyanate cross-linker and cured at a moderate temperature of about 50°C. The solvent system can be a single solvent or a mixture of solvents to aid in the dissolution or dispersion of the polymer. The solvent can be a solvent selected as a polymerization medium or added after the polymerization is completed. The solvent is selected from solvents with lower boiling points to facilitate drying and have lower toxicity for implant applications. Examples of these solvents include aliphatic ketones, esters, ethers, alcohols, hydrocarbons, and the like. Depending on the final thickness of the biointerface / drug release layer and the solution viscosity (related to the percentage of polymer solids), the coating can be applied in a single step or multiple repeated steps (such as dipping) of the selected process to build the desired thickness. In yet other examples, the biointerface polymer is formed from a polyurethaneurea incorporating unsaturated hydrocarbon groups and sulfobetaine groups in the polymer and a nonionic hydrophilic polyethylene oxide segment, wherein the polyurethaneurea polymer is dissolved in an organic or non-organic solvent system in the coating formulation and cross-linked with heat or radiation (including UV, LED light, electron beam, etc.) in the presence of an initiator and cured at a moderate temperature of about 50° C. Examples of unsaturated hydrocarbons include allyl, vinyl, acrylate, methacrylate, olefin, alkyne, etc.

[0199] In some examples, a tether is used. The tether is a polymer or chemical part that does not participate in the (electro)chemical reaction involved in sensing, but forms a chemical bond with the (electro)chemically active component of the membrane. In some examples, these bonds are covalent bonds. In one example, a tether can be formed in a solution before forming one or more interlayers of the membrane, wherein the tether directly binds the two (electro)chemically active components to each other, or alternatively, the tether binds the (electro)chemically active components to the polymer backbone structure. In another example, the (electro)chemically active components are co-mixed with a cross-linking agent (and optional polymer) having an adjustable length, and the tethering reaction occurs as an in-situ cross-linking. Tethering can be used to maintain a predetermined number of degrees of freedom of NAD (P) H for effective enzyme catalysis, wherein "effective" enzyme catalysis causes the analyte sensor to continuously monitor one or more analytes for a period of about 5 days to about 15 days or longer.

[0200] Membrane manufacturing

[0201] Polymers can be processed by solution-based techniques such as spraying, dipping, casting, electrospinning, vapor deposition, spin coating, coating, etc. Water-based polymer emulsions can be made into films by methods similar to those used for solvent-based materials. In both cases, the evaporation of volatile liquids (e.g., organic solvents or water) leaves behind a polymer film. Crosslinking of deposited films or layers can be performed using multifunctional reactive ingredients by many methods. Liquid systems can be cured by heat, moisture, high-energy radiation, ultraviolet light, or by completing reactions to produce the final polymer in a mold or on a substrate to be coated.

[0202] In some examples, the wetting properties of the membrane (and the degree of sensor drift exhibited by the extended sensor) can be adjusted and / or controlled by creating covalent crosslinks between polymers containing surface active groups, polymers containing functional groups, polymers having zwitterionic groups (or their precursors or derivatives), and combinations thereof. Crosslinking can have a significant effect on the membrane structure, which in turn can affect the surface wetting properties of the membrane. Crosslinking can also affect the tensile strength, mechanical strength, water absorption rate, and other properties of the membrane.

[0203] Crosslinked polymers can have different crosslink densities. In some examples, a crosslinking agent is used to promote crosslinking between the layers. In other examples, instead of (or in addition to) the above-mentioned crosslinking techniques, heat is used to form crosslinks. For example, in some examples, due to high temperature, imide and amide bonds can be formed between two polymers. In some examples, photocrosslinking is performed to form covalent bonds between the polycationic layer and the polyanionic layer. A major advantage of photocrosslinking is that it provides the possibility of patterning. In some examples, patterning is performed using photocrosslinking to modify the membrane structure and therefore regulate the wetting properties of the membrane and membrane system, as discussed herein.

[0204] Polymers having domains or segments functionalized to allow crosslinking can be prepared by at least the methods discussed herein. For example, polyurethaneurea polymers having aromatic segments or aliphatic segments containing electrophilic functional groups (e.g., carbonyl, aldehyde, anhydride, ester, amide, isocyano, epoxy, allyl or halide groups) can be crosslinked with a crosslinking agent having multiple nucleophilic groups (e.g., hydroxyl, amine, urea, carbamate or thiol groups). In another example, polyurethaneurea polymers having aromatic segments or aliphatic segments containing nucleophilic functional groups can be crosslinked with a crosslinking agent having multiple electrophilic groups. In one example, a polycarbodiimide crosslinking agent is used. In addition, polyurethaneurea polymers having hydrophilic segments containing nucleophilic functional groups or electrophilic functional groups can be crosslinked with a crosslinking agent having multiple electrophilic functional groups or nucleophilic groups. Unsaturated functional groups on polyurethaneurea can also be used for crosslinking by reacting with multivalent free radical reagents. Non-limiting examples of suitable cross-linking agents include isocyanates, carbodiimides, glutaraldehyde, aziridine, silanes or other aldehydes, epoxies, acrylates, free radical-based reagents, ethylene glycol diglycidyl ether (EGDE), poly (ethylene glycol) diglycidyl ether (PEG-DE) or dicumyl peroxide (DCP). In one example, about 0.1 wt % to about 15 wt % of a cross-linking agent is added relative to the total dry weight of these ingredients added when the cross-linking agent and polymer are blended. In another example, about 1 wt % to about 10 wt % of a cross-linking agent is added relative to the total dry weight of these ingredients added when the cross-linking agent and polymer are blended. In yet another example, about 5 wt % to about 15 wt % of a cross-linking agent is added relative to the total dry weight of these ingredients added when the cross-linking agent and polymer are blended. During the curing process, it is believed that substantially all of the cross-linking agent reacts, leaving substantially no detectable unreacted cross-linking agent in the final film.

[0205] The polymers disclosed herein can be formulated into a mixture that can be stretched into a film or applied to a surface using methods such as spraying, self-assembled monolayers (SAMs), painting, dip coating, vapor deposition, molding, 3D printing, slot coating, pico jet printing, piezoelectric inkjet printing, lithography (e.g., photolithography), micro- and nano-pipette printing, screen printing, etc. The mixture can then be cured at an elevated temperature (e.g., about 30° C. to about 150° C.). Other suitable curing methods may include, for example, ultraviolet radiation, electron beam, or gamma radiation.

[0206] In some cases, using a continuous multi-analyte monitoring system including a sensor configured with a bioprotective and / or drug-releasing membrane, it is believed that foreign body reaction is a major event surrounding the extended implantation of an implanted device and can be managed or manipulated to support rather than hinder or block analyte transport. On the other hand, in order to extend the life of the sensor, an example is, for example, using a material that promotes vascularized tissue ingrowth in a porous biointerface membrane. For example, tissue ingrowth into a porous biointerface material surrounding a sensor can promote sensor function over an extended period of time (e.g., weeks, months, or years). It has been observed that the ingrowth and formation of a tissue bed may take up to 3 weeks. Tissue ingrowth and tissue bed formation are considered to be part of the foreign body reaction. As will be discussed herein, foreign body reaction can be manipulated by using a porous bioprotective material that surrounds the sensor and promotes tissue and microvasculature to grow ingrowth over time.

[0207] Thus, sensors as discussed in the examples herein may include a biointerface layer. Similar to the drug release layer, the biointerface layer may include, but is not limited to, for example, a porous biointerface material including a solid portion and interconnected cavities, all of which are described in more detail elsewhere herein. The biointerface layer may be used to improve sensor function long-term (e.g., after tissue ingrowth).

[0208] Therefore, the sensor as discussed in the examples herein may include a drug release membrane that at least partially acts as a biointerface membrane or is combined with a biointerface membrane. The drug release membrane may include, for example, a material comprising a hard-soft segment polymer having a hydrophilic and optional hydrophobic domain, all of which are described in more detail elsewhere herein and can be used to improve sensor function (e.g., after tissue ingrowth) over the long term. In one example, a material comprising a hard-soft segment polymer having a hydrophilic and optional hydrophobic domain is configured to release a combination of a derivative form of dexamethasone or dexamethasone acetate and dexamethasone, thereby achieving one or more different release rates of an anti-inflammatory agent and extending the service life of the sensor. Other suitable drug release membranes of the present disclosure may be selected from silicone polymers; polytetrafluoroethylene; expanded polytetrafluoroethylene; polyethylene-co-tetrafluoroethylene; polyolefins; polyesters; polycarbonates; biostable polytetrafluoroethylene; homopolymers, copolymers, terpolymers of polyurethane; polypropylene (PP); polyvinyl chloride (PVC); polyvinylidene fluoride (PVDF); polyvinyl alcohol (PVA); polyvinyl acetate; ethylene vinyl acetate (EVA); polybutylene terephthalate (PBT); polymethyl methacrylate (PMMA); polyetheretherketone (PEEK); polyamides; polyurethanes and copolymers and blends thereof; polyurethaneurea polymers and copolymers and blends thereof; cellulosic polymers and copolymers and blends thereof; poly( and copolymers and blends thereof; poly(ethylene oxide) and copolymers and blends thereof; poly(propylene oxide) and copolymers and blends thereof; polysulfones and block copolymers thereof, including, for example, diblock, triblock, alternating, random and graft copolymers; cellulose; hydrogel polymers; poly(2-hydroxyethyl methacrylate) (pHEMA) and copolymers and blends thereof; hydroxyethyl methacrylate (HEMA) and copolymers and blends thereof; polyacrylonitrile-polyvinyl chloride (PAN-PVC) and copolymers and blends thereof; acrylic acid copolymers and copolymers and blends thereof; nylon and copolymers and blends thereof; polyvinylidene fluoride; polyanhydrides; poly(l-lysine); poly(L-lactic acid); hydroxyethyl methacrylate and copolymers and blends thereof; hydroxyapatite and copolymers and blends thereof.

[0209] Sensing mechanism

[0210] In general, the analyte sensors of the present disclosure include a sensing mechanism having a small structure in at least a portion thereof (e.g., a micro-diameter or small-diameter sensor with a small structure), such as a coaxial or planar sensor. As used herein, "small structure" refers to a structure having at least one dimension less than about 1 mm. The small structure sensing mechanism can be coaxial-based, or substrate-based (a flat or substantially planar substrate, which can be single-sided or double-sided, which can or can include one or more sensor elements on any side or surface), or any other architecture. In some alternative examples, the term "small structure" can also refer to slightly larger structures, such as those whose smallest dimension is greater than about 1 mm, however, the construction (e.g., mass or size) is designed to minimize foreign body reactions due to size and / or mass.

[0211] The present disclosure includes a sensor system with two or more sensors, each sensor being configured to sense different analytes. Two or more sensors may be configured to act independently or simultaneously, to sense two or more analytes simultaneously, sequentially and / or randomly (it includes events that can occur independently in picoseconds, nanoseconds, milliseconds, seconds or minutes) or in an alternating or overlapping manner. Two or more sensors of a sensor system may be coupled to an electronic device, such as a single transmitter or receiver, in a manner that can communicate. Two or more sensors of a sensor system may be coupled to separate independent electronic devices in a manner that can communicate.

[0212] In one example of a continuous analyte monitoring system, a first single sensor is configured to continuously monitor at least a first analyte (e.g., glucose, glycerol, lactate, bilirubin, oxygen, etc.) and a second different analyte. In this example, a single sensor may include a single coaxial or planar sensor configured to monitor at least a first analyte and a second analyte. In another example, a first sensor is configured to monitor a first analyte, and a second sensor is configured to continuously monitor a second analyte (e.g., ketone). Each of the first sensor and the second sensor may be planar, substantially planar, or coaxial, or a combination of two or more top, side, or cross-sectional geometries. In one example, each of the first sensor and the second sensor is connected to the same sensor electronics and networking element in a manner that can communicate to continuously monitor a device and provide feedback to the device, such as a mobile device, a tablet computer, a laptop, wearable technology (clothing, jewelry, other accessories), or other IoT (Internet of Things) devices or combinations of devices. In another example, the first sensor and the second sensor are connected to independent sensor electronics and networking elements in a manner that can communicate. Each of the first sensor and the second sensor is positioned in the subcutaneous layer of the subject through the skin layer. In another example, the sensor system is configured as a monolithic sensor body having both a first sensor and a second sensor, and its electrodes are configured to detect two or more analytes. At least one of the multiple electrodes of the sensor system is configured to detect the first analyte, and the second multiple electrodes are configured to detect the second analyte. The sensor system is positioned in the subcutaneous layer of the subject through the skin layer. In another example, the sensor system includes a first sensor and a second sensor, wherein each sensor of the sensor system includes one or more fiber elements (fiber element). For example, two or more sensors such as the first sensor and the second sensor can be separated from the body, in the body, or separated from the body and in the body to be electrically, mechanically or otherwise connected together. Each of the first sensor and the second sensor of the sensor system is positioned in the subcutaneous layer of the subject through the skin layer.

[0213] The multi-analyte sensor devices and systems discussed herein may include elements such as on-body wearable devices, wireless communication capabilities, electronics, software, GUIs, or other elements configured to enable an analyte monitoring system to continuously monitor analyte levels in a recipient. Various alarms and actions may be taken in response to this monitoring. As discussed herein, an "on-body" device or wearable device includes a device configured to be coupled to a recipient for at least a predetermined period of time via one or more coupling elements, the one or more coupling elements including in-body components such as sensors and / or adhesives, mechanical elements, electrical elements, magnetic elements, or other combinations of elements.

[0214] Sensing membrane

[0215] In some examples, as shown in FIG. 1 , a sensing membrane is disposed on an electroactive surface of a continuous multi-analyte sensor 100 and includes one or more domains or layers. Generally speaking, the function of the sensing membrane is to control the flow of a biological fluid through it and / or to protect sensitive areas of the sensor from, for example, contamination by the biological fluid. Some 1 electrochemical enzyme-based analyte sensors typically include a sensing membrane that controls the flow of the measured analyte, protects the electrode from contamination by the biological fluid, and / or provides, for example, an enzyme that catalyzes the reaction of the analyte with a cofactor. See, for example, U.S. Patent Application Publication No. 2005 / 0245799 to Brauker et al. and U.S. Patent No. 7,497,827 to Brister et al., which are incorporated herein by reference in their entirety.

[0216] The sensing film of the present disclosure may include any film configuration applicable to any analyte sensor (such as described in more detail above). Generally speaking, the sensing film of the present disclosure includes one or more domains, all or some of which may adhere to or be deposited on the analyte sensor, as understood by those of ordinary skill in the art. In one example, the sensing film generally provides one or more of the following functions: 1) protect the exposed electrode surface from the influence of the biological environment, 2) the diffusion resistance (restriction) of the analyte, 3) the catalyst for realizing the enzymatic reaction, 4) limit or block the interfering substance, and 5) the hydrophilicity at the electrochemical reactive surface of the sensor interface, as described in U.S. Patent No. 7,497,827 cited above to Brister et al. The sensing film discussed herein may include one or more adhesive layers between two adjacent film layers. In one example, the one or more adhesive layers may increase robustness and adhesion, thus improving the sensing film integrity. In various examples, the adhesive layer may include a silane group, polyvinyl alcohol (PVA), glutaraldehyde, or a silicone-based or silicone-containing material or a combination of other adhesives or adhesives.

[0217] Electrode domain

[0218] In some examples, the membrane system includes an optional electrode domain. The electrode domain is provided to promote and / or enhance the electrochemical reaction between the electroactive surface of the working electrode and the electroactive surface of the reference electrode, so the electrode domain is located closer to these electroactive surfaces than the enzyme domain. In some examples, the electrode domain includes a semipermeable coating that maintains a water layer at the electrochemically reactive surface of the sensor, for example, a wetting agent in an adhesive material can be used as an electrode domain; This allows ions to be fully transported in an aqueous environment. The electrode domain can also help stabilize the operation of the sensor by overcoming electrode startup and drift problems caused by insufficient electrolytes. The material forming the electrode domain can also protect the sensor from pH-mediated damage, which may be caused by a large pH gradient formed due to the electrochemical activity of the electrode.

[0219] In one example, the electrode domain includes a flexible water-swellable hydrogel film with a "dry film" thickness of about 0.05 microns or less to about 20 microns or more. In some examples, the "dry film" thickness is about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 1, 1.5, 2, 2.5, 3 or 3.5 microns to about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 19.5 microns. In another example, the "dry film" thickness is about 2, 2.5 or 3 microns to about 3.5, 4, 4.5 or 5 microns. "Dry film" thickness refers to the thickness of the cured film cast from the coating formulation by standard coating techniques.

[0220] In some examples, the electrode domain is formed of a curable mixture of a urethane polymer and a hydrophilic polymer. The coating is formed of a polyurethane polymer having carboxylate functional groups and nonionic hydrophilic polyether segments, wherein the polyurethane polymer is cross-linked with a water-soluble carbodiimide (e.g., 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) or a polycarbodiimide crosslinker) in the presence of polyvinyl pyrrolidone and cured at an appropriate temperature of about 50°C.

[0221] In some examples, the electrode domain is deposited by spraying or dipping the electroactive surface of the sensor. In another example, the electrode domain is formed by dipping the electroactive surface in the electrode solution and curing the domain at a temperature of about 40°C to about 55°C for about 15 minutes to about 30 minutes (and can be done under vacuum (e.g., 20mmHg to 30mmHg)). In the example where the electrode domain is deposited by dip coating, a functional coating is provided with an insertion rate of about 1 inch / minute to about 3 inches / minute, a residence time of about 0.5 minutes to about 2 minutes, and a removal rate of about 0.25 inches / minute to about 2 inches / minute. However, as will be understood by those of ordinary skill in the art, in some examples, values ​​other than those listed above may be acceptable or even desirable, for example, depending on viscosity and surface tension. In one example, the electroactive surface of the electrode system is dip coated once (one layer) and then cured in a vacuum at 50°C for 20 minutes.

[0222] As discussed herein, the insertable portion coating composition applied to the insertable portion can have a viscosity of about 10 centipoise (cP) to about 350 cP. In another example, the insertable portion coating composition applied to the insertable portion has a viscosity of about 20 cP to about 200 cP. In yet another example, the insertable portion coating composition applied to the insertable portion has a viscosity of about 30 cP to about 300 cP.

[0223] Although separate electrode domains are described herein, in some examples, sufficient hydrophilicity can be provided in the interference domain and / or the enzyme domain (depending on which domain is adjacent to the electroactive surface) to provide complete transport of ions in an aqueous environment (e.g., without a distinct electrode domain).

[0224] Unmediated System Interference Domain

[0225] In some examples, for the non-mediated system disclosed herein, an optional interference domain is provided, which generally includes a polymer domain that limits the flow of one or more interferences to the working electrode. In some examples, the interference domain acts as a molecular sieve, which allows the analyte and other substances to be measured by the electrode to pass through, while preventing other substances (including interferences such as ascorbate and urea) from passing through (see U.S. Patent No. 6,001,067 granted to Shults). Some known interferences of glucose oxidase-based electrochemical sensors include acetaminophen, ascorbic acid, bilirubin, cholesterol, creatinine, dopamine, ephedrine, ibuprofen, levodopa, methyldopa, salicylate, tetracycline, tolazamide, tolbutamide, triglycerides and uric acid.

[0226] Several polymer types can be used as the base material for the interference domain, including, for example, polyurethanes, polymers with ionic side groups (e.g., polyurethane-zwitterions), NAFIONs, TM , chitosan, cellulose or alternating layers of polyallylamine and polyacrylic acid, etc., and polymers with controlled pore size. In one example, the interference domain includes a hydrophobic film that is non-swellable and restricts the diffusion of low molecular weight substances. The interference domain is permeable to relatively low molecular weight substances, such as hydrogen peroxide, but restricts the passage of higher molecular weight substances including glucose and ascorbic acid. In one example, the interference domain includes a charged substance (e.g., a polymer with charged side groups as disclosed herein) whose function is to interact with one or more substances of the sensing system (such as a cofactor) to reduce or eliminate migration from the domain.

[0227] Other systems and methods for reducing or eliminating interfering substances that can be applied to the membrane system of the present disclosure are described in U.S. Patent No. 7,816,004 to Muradov et al., U.S. Patent Application Publication No. 2005 / 0176136 to Burd et al., U.S. Patent No. 7,081,195 to Simpson et al., and U.S. Patent No. 7,715,893 to Kamath et al. In some alternative examples, a distinct interference domain is not included.

[0228] In one example, for dry film domain thicknesses of about 0.05 microns or less to about 20 microns or more, the interference domain is deposited on the electrode domain (or directly on the electroactive surface when no distinct electrode domain is included). In other examples, the dry film domain thickness is about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 1, 1.5, 2, 2.5, 3 or 3.5 microns to about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 19.5 microns. In other examples, the dry film domain thickness is about 2, 2.5 or 3 microns to about 3.5, 4, 4.5 or 5 microns. Thicker films may also be useful, but in some examples, thinner films have a lower effect on the diffusion rate of the electroactive species from the enzyme membrane to the electrode.

[0229] As discussed herein, when two or more sensors are employed in a sensor system, each sensor optionally includes an interference domain configured to prevent the same interferents from penetrating the membrane. In another example, when two or more sensors are employed in a sensor system, each sensor optionally includes an interference domain configured to prevent different, or overlapping, but also different interferents from penetrating the membrane.

[0230] Mediated System-Interference Domain

[0231] Some second-generation electrochemical analyte sensor technologies (2 nd -gen) utilizes an immobilized redox mediator to reduce the overpotential required to detect the analyte. This reduction can be significant compared to the typical operating potential of first-generation electrochemical analyte sensors (1st-gen, for example, those sensors that operate based on the principle of hydrogen peroxide detection on a catalytic metal surface). For example, second-generation analyte sensors can be biased between +0.0V and +0.3V, while first-generation sensors are biased between +0.5 and +0.8V. However, despite this reduction in operating potential and reduced sensitivity to electroactive interferences from endogenous and pharmacological agents, these second-generation sensors can still succumb to the excessive effects of residual interferences.

[0232] For example, an exemplary second generation analyte sensor utilizes a polymer-bound covalently bound redox mediator (e.g., polyvinyl imidazole (PVI)-Os(4,4′-dimethyl-2,2′-bipyridine)2Cl] + / 2+ ), which reduces the overpotential required for enzymatic detection of target analytes. Examples of such mediator-based sensors include systems where undue signal contributions from the presence of co-circulating endogenous electroactive species are demonstrated by product labeling warnings regarding large doses of ascorbic acid / ascorbate ions (i.e., vitamin C), which may result in false hyperglycemia warnings, etc. While charge-selective membranes or further reductions in overpotential may mitigate such interfering effects, they may result in material impacts on sensitivity and signal-to-noise figure of merit. Thus, currently, mediated electrochemical analyte sensing systems continue to display undue signal contributions from endogenous metabolites such as ascorbic acid.

[0233] Therefore, the present disclosure includes a mediated system interference domain developed for a second generation sensor system, whether they are continuous blood glucose monitoring or multi-analyte monitoring, such as ketone-glucose monitoring, the mediated system interference domain includes one or more oxidases, which cause interfering metabolites or metabolites to be enzymatically degraded into peroxide products, such as hydrogen peroxide. The present disclosure provides a domain including an oxidase alone or in combination with any conventional membrane (electrode, enzyme, resistance domain / layer), which is used with a built-in second generation (e.g., mediated) analyte sensor. Exemplary oxidases include, for example, ascorbic acid oxidase or urate oxidase, which are configured to catalyze the conversion of undesirable interfering substances (e.g., ascorbic acid, uric acid) into hydrogen peroxide products, which exhibit significantly less impact at the bias voltage / overpotential conventionally applied in the second generation sensing system. This conversion provides a reduced total concentration of interfering substances at the electrode surface (e.g., the flux of interfering substances is exchanged with the flux of hydrogen peroxide), which provides a lower harmful effect on the sensed signal than originally in the presence of interfering substances. The mediated system interference domains may be used alone or in combination with other interference domains, interference membranes, or interference domains that may include the same polymer matrix, for example, without one or more oxidases, peroxidases, or catalases.

[0234] In some examples of mediated system interference domains, the oxidase can be combined with one or more peroxidases or peroxidase-like enzymes (e.g., horseradish peroxidase, catalase) to further cleave the hydrogen peroxide product produced from the oxidase, thereby rendering the peroxide electroactive agent inert and unable to undergo redox reactions at the electrode surface. The present disclosure includes deploying mediated system interference domains in one or more of an electrode domain, an enzyme domain, a resistance domain, and an interference membrane. The present disclosure includes deploying mediated system interference domains in one or more of an electrode domain, an enzyme domain, a resistance domain, and an interference domain.

[0235] Thus, in one example, using the exemplary ketone / glucose multi-analyte sensor system, a mediated system interference domain may be included, the mediated system interference domain including at least one of ascorbate oxidase, urate oxidase, horseradish peroxidase, or catalase, present in an enzyme domain including a dehydrogenase (e.g., β-hydroxybutyrate dehydrogenase, a NADH-acting enzyme (e.g., diaphorase, NAD(P)H dehydrogenase), a redox polymer (e.g., PVI-Os(bpy)2Cl), an optional cofactor (e.g., NAD+, NADP+ if desired), and optionally cross-linked, for example, using PEG-DGE, CDI, or a polycarbodiimide cross-linker. Resistance domains of biocompatible materials or blends of hydrophobic / hydrophilic polymers (e.g., PVP / PEG-DGE) may be applied to the enzyme domain / mediated system interference domain.

[0236] In another example, using an exemplary ketone / glucose multi-analyte sensor system, a mediated system interference domain including at least one of ascorbate oxidase, urate oxidase, horseradish peroxidase, or catalase is present in a resistance domain including a biocompatible material or a blend of hydrophobic / hydrophilic polymers (e.g., PVP / PEG-DGE). A separate enzyme domain may be located near the electrode and adjacent to the mediated system interference domain present in the resistance domain, the enzyme domain including a dehydrogenase (e.g., β-hydroxybutyrate dehydrogenase, a NADH-acting enzyme (e.g., diaphorase, NAD(P)H dehydrogenase), a redox polymer (e.g., PVI-Os(bpy)2Cl), an optional cofactor (e.g., NAD+, NADP+, if desired), and optionally cross-linked, for example, using PEG-DGE or a polycarbodiimide cross-linker.

[0237] In another example, using the exemplary ketone / glucose multi-analyte sensor system, a system interference domain mediated by at least one of ascorbate oxidase, urate oxidase, horseradish peroxidase, or catalase is present between the enzyme domain and at least one electrode surface. A resistance domain of a biocompatible material or a blend of hydrophobic / hydrophilic polymers such as PVP / PEG-DGE can be applied to the enzyme domain.

[0238] In other examples, exemplary ketone or ketone / glucose multi-analyte sensor systems without mediators are provided, as further discussed herein. In one example, exemplary ketone or ketone / glucose multi-analyte sensor systems are provided that are free of metal-based mediators, such as osmium complexes of biimidazole and / or imidazole ligands. In one example, exemplary ketone or ketone / glucose multi-analyte sensor systems are provided that are free of metal-based mediators, such as osmium complexes of biimidazole and / or imidazole ligands, and are configured to provide an amperometric signal at an applied voltage greater than +0.2V, greater than or equal to +0.3V, greater than or equal to +0.4V, greater than or equal to +0.5V, or greater than or equal to +0.6V. In one example, exemplary ketone or ketone / glucose multi-analyte sensor systems that do not have metal-based mediators and include an interference layer are provided. In one example, an exemplary ketone or ketone / glucose multi-analyte sensor system is provided that lacks a metal-based mediator, such as an osmium complex of a biimidazole and / or imidazole ligand, that is configured to provide an amperometric signal at an applied voltage greater than +0.2 V, greater than or equal to +0.3 V, greater than or equal to +0.4 V, greater than or equal to +0.5 V, or greater than or equal to +0.6 V, and includes an interference layer.

[0239] transduction element domain

[0240] In one example, the membrane system also includes a transduction element domain, such as an enzyme, RNA, DNA, aptamer, binding protein, etc., which is disposed further away from the electroactive surface than the interference domain (or when no obvious interference domain is included, the electrode domain). In some examples, the transduction element domain is deposited directly onto the electroactive surface (when neither the electrode nor the interference domain is included). In one example, the transduction element domain provides an enzyme that catalyzes the reaction of the analyte and its co-reactant, as described in more detail below. In some examples, the transduction element domain includes glucose oxidase; however, other oxidases, such as galactose oxidase or uricase, may also be used.

[0241] In order to make the enzyme-based electrochemical sensor work effectively and accurately, the response of the sensor is not limited by the enzyme activity and the concentration of the co-reactant. Enzymes including glucose oxidase will be inactivated over time even under ambient conditions, so this behavior is compensated when the enzyme domain is formed. In some examples, the enzyme domain is composed of an aqueous dispersion of a colloidal polyurethane polymer containing an enzyme. However, in an alternative example, the enzyme domain is composed of an oxygen-enhancing material, such as at least one of silicone or fluorocarbon, to provide excess oxygen to ensure that oxygen does not limit the sensing reaction. In some examples, the enzyme is fixed in the enzyme domain. See U.S. Patent No. 7,379,765 of Petisce et al.

[0242] In one example, the transduction element domain is deposited onto the interference domain to obtain a "dry film" domain thickness of about 0.05 microns or less to about 20 microns or more. In other examples, the dry film domain thickness is about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 1, 1.5, 2, 2.5, 3, or 3.5 microns to about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 19.5 microns. In other examples, the dry film domain thickness is about 2, 2.5, or 3 microns to about 3.5, 4, 4.5, or 5 microns. "Dry film" thickness refers to the thickness of a film cast from a coating formulation by standard coating techniques, including post-curing of the film.

[0243] However, in some examples, the transduction element domain is deposited onto the electrode domain or directly onto the electroactive surface. In some examples, the transduction element domain is deposited by spraying or dipping, slot coating, 3D printing, skin jet printing, piezoelectric inkjet printing, etc. In other examples, the transduction element domain is formed by dipping the electrode domain in a transduction element domain solution and curing the transduction element domain at a temperature of about 40°C to about 55°C for about 15 minutes to about 30 minutes (and can be done under vacuum (e.g., 20 mmHg to 30 mmHg)). In examples where the transduction element domain is deposited at room temperature using dip coating, a functional coating is provided with an insertion rate of about 1 inch / minute to about 3 inches / minute, a residence time of about 0.5 minutes to about 2 minutes, and a removal rate of about 0.25 inches / minute to about 2 inches / minute. However, as will be appreciated by one of ordinary skill in the art, in some examples, values ​​other than those listed above may be acceptable or even desirable, for example depending on viscosity and surface tension. In one example, the transduction element domain is formed by dipping twice in the coating solution (that is, forming two layers) and curing in a vacuum at 50° C. for 20 minutes. However, in some examples, the transduction element domain can be formed by dipping and / or spraying one or more layers at a predetermined coating solution concentration, insertion rate, residence time, removal rate, and / or desired thickness. In yet another example, the transduction element layer is formed by a plurality of interlayers deposited by a self-assembled monolayer (SAM), which is typically formed by immersion in a solution that promotes surface chemistry. The substrate can be placed in the solution for a period of about 30 minutes to about 24 hours to form a desired transduction element layer of a predetermined thickness. In another example, the substrate can be placed in the solution for a period of about 1 hour to about 18 hours. In another example, the substrate can be placed in the solution for a period of about 3 hours to about 12 hours.

[0244] In yet another example, the transduction element layer is formed of multiple interlayers. One or more interlayers of the transduction element layer can be varied individually or in combination in various aspects such as chemistry (composition), thickness or other mechanical, electrical, biological or other material properties to achieve a target electron mobility or electron mobility range through each interlayer.

[0245] Resistance Domain

[0246] In one example, the membrane system includes a resistance domain that is further away from the electroactive surface than the enzyme domain. Although the following description relates to the resistance domain of the glucose sensor, the resistance domain can also be modified for promoting the concentration detection of other analytes and co-reactants. In one example, the resistance domain is configured to control the oxygen flux through the membrane. In another example, the resistance domain is configured to control the flux of analytes or co-reactants other than oxygen through the membrane. In another example, the resistance domain is configured to control the flux of two or more analytes through the membrane.

[0247] Glucose sensors based on immobilized enzymes that use oxygen as a co-reactant obtain oxygen supply in a non-rate-limited excess manner so that the sensor responds linearly to changes in glucose concentration without responding to changes in oxygen concentration. Specifically, when the glucose monitoring reaction is an oxygen-restricted reaction, linearity cannot be achieved above the minimum concentration of glucose. In the absence of a semipermeable membrane located above the enzyme domain to control the flux of glucose and oxygen, a linear response to glucose levels can be obtained only for glucose concentrations up to about 40 mg / dL. However, in a clinical setting, it is expected that a linear response to glucose levels can also be obtained up to at least about 400 mg / dL.

[0248] In one example, the resistance domain includes a semipermeable membrane that controls the flux of oxygen and glucose to the enzyme domain below, allowing oxygen to flow in a non-rate limiting excess. As a result, the linear upper limit of the glucose measurement result is extended to a much higher value than that achieved without the resistance domain. In one example, the resistance domain exhibits an oxygen to glucose permeability ratio of about 50:1 or less to about 400:1 or greater. In another example, the oxygen to glucose permeability ratio is about 200:1.

[0249] In an alternative example, a lower oxygen to glucose ratio may be sufficient to provide excess oxygen by using a high oxygen solubility domain (e.g., a silicone or fluorocarbon based material or domain) to enhance the supply / transport of oxygen to the transduction element domain. If more oxygen is supplied to the enzyme, more glucose can also be supplied to the transduction element without creating an oxygen rate limiting excess. In an alternative example, the resistance domain is formed of a silicone composition, such as described in U.S. Patent Application Publication No. 2005 / 0090607 to Taptaak ​​et al.

[0250] In one example, the resistance domain includes a polyurethane film having both a hydrophilic region and a hydrophobic region. The hydrophilic region and the hydrophobic region can be used in combination to control the diffusion of one or more analytes (e.g., glucose, oxygen, ketones, lactic acid, uric acid, etc.) to the analyte sensor. Suitable hydrophobic polymer components are polyurethane or polyurethane urea. Polyurethane is a polymer prepared by the condensation reaction of diisocyanate and a difunctional hydroxyl-containing material. Polyurethane urea is a polymer prepared by the condensation reaction of diisocyanate and a difunctional amine-containing material. In polyurethane and polyurethane urea polymers, hard segments or soft segments may include a variety of different chemical structures, such as soft segments may include hydrophobic and hydrophilic segments.

[0251] Exemplary diisocyanates that can be used as hard segment components of polyurethane or polyurethane urea polymers of the present disclosure include aliphatic diisocyanates containing about 4 to about 8 methylene units. Diisocyanates containing alicyclic moieties can also be used to prepare polymers and copolymer components of the membrane of the present disclosure. The material forming the basis of the hydrophobic matrix of the resistance domain can be selected to show enough permeability to allow related compounds to pass therethrough (for example, to allow oxygen molecules to pass through the membrane from the sample being examined so as to reach the active enzyme electrode or electrochemical electrode). Examples of materials that can be used to prepare non-polyurethane type membranes include vinyl polymers (including polyvinyl imidazole and polyvinyl pyridine), polyethers, polyesters, polyamides, inorganic polymers (such as polysiloxanes and polycarbosiloxanes), natural polymers (such as cellulose-based materials and protein-based materials), and mixtures or combinations thereof. In some examples, these non-polyurethane type membranes include crosslinking agents in addition to base polymers to improve mechanical properties and / or regulate the mass transport of analytes or other substances. In some examples, the resistance domain can be polyvinyl butyral (PVB). In other examples, the base polymer can be a segmented block copolymer. In another example, the hard segment can be about 15% to about 75% by weight. In another example, the hard segment can be about 25% to about 55% by weight. In another example, the hard segment can be about 35% to about 45% by weight. For example, the base polymer may include polyurethane and / or polyurea segments and one or more of polycarbonate, polydimethylsiloxane (PDMS), polyether, fluorine-modified segments, perfluoropolyols, or polyester segments. In other examples, the base polymer may be a polyurethane copolymer selected from the group including polyether-urethane-urea, polycarbonate polyurethane, polyether-urethane, polyester-urethane, and / or their copolymers.

[0252] In one example, the hydrophilic polymer component of the resistance domain is polyethylene oxide. For example, a kind of available hydrophobic-hydrophilic copolymer component is a polyurethane polymer including about 1% by weight to about 50% by weight of polyethylene oxide (PEO). In one example, the resistance domain includes 5% by weight to about 30% by weight of polyethylene oxide (PEO). In another example, the resistance domain includes about 10% by weight to about 40% by weight of PEO. The polyethylene oxide portion of the copolymer is thermodynamically driven to separate from the hydrophobic portion and the hydrophobic polymer component of the copolymer. The polyethylene oxide-based soft segment portion of the copolymer used to form the final blend affects the absorption of water by the membrane and the subsequent permeability of the membrane to glucose.

[0253] In one example, one or more of NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI or HDI, diisocyanates are used to form various polyurethanes and polyurethaneureas for resist domains and / or other sensor domains. In one example, the polyurethanes and polyurethaneureas have aliphatic or amphiphilic soft segments. In one example, the soft segments include diols, diamines, diesters or dicarbonates. In one example, the soft segments are composed of two or more of a plurality of diols, diamines, diesters or dicarbonates.

[0254] In one example, one or more of NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI, HDI is reacted with one or more dicarbonates, polyethers, polyesters, polyalkyl-diols, or polyalkyl-diamines.

[0255] In one example, one or more of NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI, HDI and a C5 or C6 dicarbonate such as U90OXYMER TM In one example, NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI, HDI or a mixture thereof is reacted with a C5 or C6 dicarbonate, such as U90 OXYMER TM and one or more polyethers, polyesters, polyalkylene glycols or polyalkylene diamines. In one example, the dicarbonate is sterically branched to increase the Tg of the soft segment, for example to provide a Tg near body temperature.

[0256] In one example, one or more of the hard segment diisocyanates of NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI, HDI are reacted with one or more of polyethers such as polytetrahydrofuran (PTMO), polypropylene oxide (PPO), polyethylene glycol (PEG), polybutadiene glycol (PBU) alone or in combination with polydimethylpolysiloxane (PDMS). In one example, the same polyether of different molecular weight (Mw) is used. In one example, two or more polyethers of the same or different Mw are used. In one example, one or more polyethers of the same or different Mw are used in combination with one or more PDMS polymers having the same or different Mw. Although not bound by any particular theory, as the molecular weight of the soft segment decreases, the phase mixing of different soft segment components increases. In one example, it has been observed that high molecular weight soft segments provide the formation of rich phases, which may be due to entropy contributions, etc.

[0257] In one example, one or more of the hard segment diisocyanates of NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI, HDI are reacted with one or more polyesters such as polyethylene adipate glycol (PEA), poly(ethylene adipate glycol, PBA), alone or in combination with one or more polyethers, polyalkylene glycols, or polyalkylene diamines.

[0258] In one example, NBDI, IPDI, TDI, MPDI, HMDI, MDI, 1,3-H6XDI, 1,4-H6XDI, CHDI, PPDI, TODI, HDI, or mixtures thereof are reacted with one or more polyalkylene glycols alone or in combination with one or more polycarbonates, polyethers, polyesters, or polyalkylene diamines.

[0259] In one example, the above-mentioned resistance domain is directly deposited on the electrode surface or on the enzyme domain with one or more layers to produce a resistance domain thickness of about 0.05 micron or less to about 20 microns or more. In another example, the total resistance domain thickness is about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 1, 1.5, 2, 2.5, 3 or 3.5 to about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 19.5 microns. In another example, the total resistance domain thickness is about 2, 2.5 or 3 microns to about 3.5, 4, 4.5 or 5 microns. In some examples, the resistance domain is deposited on the enzyme domain by spraying or dipping, slit coating, 3D printing, skin jet printing, piezoelectric inkjet printing. In some examples, spraying is a deposition technique. The spraying process atomizes the solution and forms a mist so that most or all of the solvent evaporates before the coating material settles on the domain below, thereby minimizing contact of the solvent with the enzyme. An additional advantage of spraying the resist domain as described in the present disclosure includes forming a membrane system that substantially blocks or resists ascorbate, a known electrochemical interferent in glucose sensors that measure hydrogen peroxide. Although not wishing to be bound by theory, it is believed that during the process of depositing the resist domain as described in the present disclosure, a structural morphology is formed that is characterized in that ascorbate is substantially impermeable therethrough.

[0260] Heterocyclic resistance domain and cofactor immobilization or retention domain

[0261] In one example, the cofactor and the enzyme are present in a domain (e.g., an enzyme and / or resistance domain) that includes a copolymer of polyvinylpyridine, polyvinylpyridine-to-styrene, polyvinylpyridine with vinyl and (meth) acrylic acid monomers, poly(styrene-to-acrylonitrile), polyvinyl imidazole or polyvinyl imidazole with vinyl and (meth) acrylic acid monomers, and / or provided as a layer adjacent to an electrode domain or electrode surface. As used herein, "polyvinylpyridine" encompasses poly-2-vinylpyridine, 3-vinylpyridine, 3-vinylpyridine, and their alkyl-substituted derivatives. Blends and / or graphs of the above polymers can be used. Blends and / or graphs of the above polymers with chitosan, amphiphilic or aliphatic polyurethanes or polyurethane ureas, polyols (PEG, PTMO, etc.) or zwitterionic polymers can be used. In some examples, polystyrene copolymers with vinyl monomers containing electron-withdrawing groups (such as nitrile) can be used. In some examples, vinyl polymers with benzene and nitrile functional groups can be used.

[0262] In one example, the cofactor and the enzyme are present in a domain (e.g., an enzyme and / or resistance domain) that includes at least partially cross-linked poly(4-vinylpyridine), polyvinylpyridine-co-styrene, copolymers of polyvinylpyridine with vinyl and (meth) acrylic acid monomers, poly(styrene-co-acrylonitrile), polyvinyl imidazole, or copolymers of polyvinyl imidazole with vinyl and (meth) acrylic acid monomers, used as a resistance domain and / or provided as a layer adjacent to an electrode domain or electrode surface. In one example, cross-linked or uncross-linked poly(4-vinylpyridine), polyvinylpyridine-co-styrene, copolymers of polyvinylpyridine with vinyl and (meth) acrylic acid monomers, poly(styrene-co-acrylonitrile), polyvinyl imidazole, or copolymers of polyvinyl imidazole with vinyl and (meth) acrylic acid monomers provide fixation or retention of one or more cofactors in a resistance domain. In one example, fixation or retention of the cofactor is via covalent bonding to a functional group of the polymer. In another example, fixation or retention of the cofactor is via non-covalent interactions, such as via a balance with a functional group of the polymer.

[0263] Examples of cofactor immobilization via non-covalent interactions with polymers include NAD+, for example, with cationic polymers (chitosan, quaternized PVPy, zwitterionic polymers, etc.) and / or polymers containing boronic acid functional groups. Thus, in one example, the cofactor and enzyme are present in a domain (e.g., an enzyme and / or resistance domain) that includes a polymer with a pendant boronic acid group that provides strong dynamic covalent bonding to the diol functionality on a cofactor such as NAD with diol functionality at certain pHs, thereby allowing NAD(H) to be fixed or retained. Thus, in one example, the ribose ring structure of NADH containing 1,2 diols and the NAD+ structure are used to associate and / or bind to one or more boronic acid functional groups via covalent interactions as shown for NADH forms in at least Schemes 1a and 1b. Similar covalent interactions are envisioned for NAD+ forms.

[0264]

[0265]

[0266] In one example, the boronic acid polymer structure and the coating solution pH are adjusted to provide sufficient association of the NAD / NADH structure, thereby reducing or eliminating migration from the polymer film. In one example, the boronic acid polymer includes styrene polymers, styrene copolymers (e.g., copolymers with acrylic acid, acrylates, acrylamides, olefins, cycloolefins), naphthyl, anthracene polymers, and copolymers thereof. In one example, the boronic acid polymer is at least partially cross-linked.

[0267] In some examples, the domains are configured to repel cofactors, for example, the RL functions to "repel" NAD(H) and not allow it to pass through, thereby attenuating its migration out of the EZL.

[0268] In another example, NAD is bound to a domain or electrode surface. In another example, NAD is directly bound to a domain or directly coupled to an electrode surface. In another example, NAD is coupled to an electrode surface with an electron transfer agent. In one example, the free amine of the adenine group of NAD(H) is extended with an alkyl chain with a primary amine to provide an EDC or (sulfo-)NHS coupling chemistry to a -COOH group on the mediator, as shown in Scheme 3, which depicts a modified NAD+ cofactor with an extended free -NH2 coupled to one of the -COOH groups in a PQQ (pyrroloquinoline quinone) mediator.

[0269] In another example, the free amine of the adenine group of NAD(H) is extended with an alkyl chain bearing a primary amine to provide EDC or (sulfo-)NHS coupling chemistry to the HBDH enzyme.

[0270] In one example, the modified NAD+ cofactor has an extended free -NH2 that can be easily cross-linked to one of the -COOH groups in the PQQ (pyrroloquinoline quinone) mediator. This PQQ mediator has another -COOH group that can then be cross-linked to a polymer backbone, an enzyme, or directly to an electrode surface.

[0271] In one example, cofactors and enzymes are present in a domain (e.g., enzyme and / or resistance domain), which includes an amphiphilic polyurethane or polyurethane urea polymer as disclosed above for a biointerface / drug release layer, an aliphatic polyurethane or polyurethane urea with a hard segment content of about 20% to 40% by weight, a polysiloxane segment of about 10% to 30% by weight, and a polyglycol segment of about 15% to 40% by weight. In one example, amphiphilic polyurethane or polyurethane urea also includes a polyvinyl pyrrolidone polymer of 0% to 25% by weight. In one example, amphiphilic polyurethane or polyurethane urea also includes a polyvinyl pyridine or alkylated or polyol-substituted pyridine polymer of 0% to 25% by weight. This amphiphilic polyurethane or polyurethane urea polymer resistance domain provides acceptable sensitivity and stability greater than two weeks. In one example, amphiphilic polyurethane or polyurethane urea polymer is at least partially cross-linked. This amphiphilic polyurethane or polyurethane urea polymer resistance domain provides sensitivity and stability compatible with the above-mentioned PVPy resistance domain.

[0272] In one example, the cofactor and enzyme are present in a domain (e.g., an enzyme and / or resistance domain) that includes an aliphatic polyurethane or polyurethane urea polymer that includes about 40% to 60% by weight of a hard segment content, about 15% to 50% by weight of a polytetramethylene oxide (PTMO) segment, and about 5% to 30% by weight of a polysiloxane segment. In one example, the aliphatic polyurethane or polyurethane urea polymer is at least partially cross-linked. In one example, a polycarbodiimide cross-linking agent is used. This aliphatic polyurethane or polyurethane urea resistance domain exhibits lower sensitivity and stability than an amphiphilic polyurethane or polyurethane urea-based resistance domain.

[0273] In one example, the cofactor and the enzyme are present in a domain (e.g., an enzyme and / or resistance domain) that includes a block copolymer obtained by polycondensation of a carboxylic acid polyamide (e.g., PA6, PA11, PA12) with a polyether (e.g., polybutylene glycol, polyethylene glycol, PEG, polytetrahydrofuran PTMO). In one example, the block copolymer obtained by polycondensation of a carboxylic acid polyamide with a polyether can be at least partially cross-linked.

[0274] In one example, the cofactor and enzyme are present in a domain (e.g., an enzyme and / or resistance domain) that includes a polyvinylpyridine-poly(ethylene glycol) diglycidyl ether (PVPy-PEG-DGE) matrix. In one example, the mass ratio of PEG-DGE to PVPy is about 1 wt % to 10 wt %. In one example, the polyvinylpyridine-PEG-DGE matrix is ​​at least partially cross-linked.

[0275] In one example, cofactors and enzymes are present in a domain (e.g., enzyme and / or resistance domain), which includes a water-dispersible polyurethane-zwitterionic polymer cross-linked with carbodiimide or polycarbodiimide. Examples of such domains include those disclosed in U.S. Patent Application Publication No. 2017 / 0191955, U.S. Patent Application Publication No. 2017 / 0188922, and U.S. Patent No. 11,112,377B2, the disclosure of which is incorporated herein by reference. In one example, the domain includes an enzyme and a polymer, which includes a polyurethane and / or polyurea segment and one or more zwitterionic repeating units. In one example, the domain includes a blend of an enzyme and a polyurethane-based polymer with polyvinylpyrrolidone. In some examples, the enzyme domain is formed by combining a polyurethane urea with a carboxybetaine group in a polymer and a nonionic hydrophilic polyethylene oxide segment, wherein the polyurethane urea polymer is dissolved in an organic or non-organic solvent system according to a predetermined coating formula, and is optionally cross-linked and / or cured. The above domain can be 0.01 μm to about 250 μm thick.

[0276] Depending on the example, the resistive domains discussed herein can be formed by a number of methods, such as, but not limited to, dip coating or spray coating of any one or more layers, depending on the concentration of the solution, insertion rate, residence time, withdrawal rate and / or desired thickness of the resulting film, or other factors or combinations of factors.

[0277] Advantageously, sensors having a membrane system of the present disclosure, including an electrode domain and / or an interference domain, an enzyme domain, and a resistance domain, provide a stable signal response to increasing glucose levels from about 40 mg / dL to about 400 mg / dL, and provide sustained functionality (at least 90% signal strength) even at low oxygen levels (e.g., at about 0.6 mg / L O2). While not wishing to be bound by theory, it is believed that the resistance domain provides sufficient resistance, or the enzyme domain provides sufficient enzyme, such that oxygen limitation is seen at much lower oxygen concentrations than prior art sensors.

[0278] In one example, a sensor signal having a current in the picoampere range is provided, which is described in more detail elsewhere herein. However, the ability to generate a signal having a current in the picoampere range can depend on a combination of factors, including electronic circuit design (e.g., A / D converter, bit resolution, etc.), membrane system (e.g., permeability of analyte through the resistance domain, enzyme concentration and / or electrolyte availability for electrochemical reactions at the electrode), and the exposed surface area of ​​the working electrode. For example, depending on the design of the electronic circuit, membrane system, and / or exposed electroactive surface area of ​​the working electrode, the resistance domain can be designed to more or less restrict the analyte.

[0279] Therefore, in one example, the membrane system is designed to have a sensitivity of about 1pA / mg / dL to about 100pA / mg / dL. In other examples, the sensitivity is about 5pA / mg / dL to 25pA / mg / dL. In another example, the sensitivity is about 4pA / mg / dL to about 7pA / mg / dL. Although it is not desired to be bound by any particular theory, it is believed that the membrane system designed to have a sensitivity within the above range allows the analyte signal to be measured in low analyte and / or hypoxic situations. That is, conventional analyte sensors show reduced measurement accuracy in low analyte ranges due to the lower availability of analytes to sensors, and / or show increased signal noise in high analyte ranges due to insufficient oxygen necessary for the amount of analyte being measured. Although it is not desired to be bound by theory, it is believed that the membrane system of the present disclosure is combined with an electronic circuit design and an exposed electrochemically reactive surface area design to support analyte measurement within the picoampere range, which enables the resolution and accuracy of improved levels to be achieved in both low and high analyte ranges, which is not visible in the prior art.

[0280] Although some of the example sensors described herein include optional interference domains to block or reduce one or more interferents, sensors with membrane systems of the present disclosure (including electrode domains, enzyme domains, and resistance domains) have been shown to inhibit ascorbate without additional interference domains. That is, the membrane systems of the present disclosure including electrode domains, enzyme domains, and resistance domains have been shown to be substantially unresponsive to ascorbate within a physiologically acceptable range. Although not wishing to be bound by theory, it is believed that as described herein, the method of depositing resistance domains by spraying results in a structural morphology that is substantially resistant to ascorbate.

[0281] Non-disruptive membrane system

[0282] Generally speaking, it is believed that suitable solvents and / or deposition methods can be selected for one or more domains of the membrane system forming one or more transition domains so that the interferer does not penetrate substantially therethrough. Therefore, a sensor without an obvious or deposited interference domain can be constructed, and the sensor is unresponsive to the interferer. Although it is not desired to be bound by theory, it is believed that a simplified multilayer membrane system, a more robust multilayer manufacturing method, and reduced variability caused by the thickness of the deposited micron-thin interference domain and the related oxygen and glucose sensitivity can be provided. In addition, the optional polymer-based interference domain that usually inhibits the diffusion of hydrogen peroxide is eliminated, thereby increasing the amount of hydrogen peroxide passing through the membrane system. In other examples, the interference domain can be configured to block or reduce the diffusion of one or more interfering substances, and the interfering substance includes H2O2, acetaminophen or other interferers or a combination of interferers.

[0283] Oxygen catheter

[0284] As described above, some sensors employ a transduction element within a membrane system through which the body fluid of the recipient passes and in which the analyte (e.g., glucose, ketone) within the body fluid reacts in the presence of a co-reactant (e.g., oxygen) to produce a product. The product is then measured electrochemically, so the output of the electrode system serves as a measure of the analyte. For example, when the sensor is a glucose sensor based on glucose oxidase, the substance measured at the working electrode is H2O2. The enzyme (glucose oxidase) catalyzes the conversion of oxygen and glucose to hydrogen peroxide and gluconate according to the following reaction:

[0285] Glucose + O2 → Gluconate + H2O2.

[0286] Because for each glucose molecule reacted there is a proportional change in the product H2O2, the change in H2O2 can be monitored to determine the glucose concentration. The oxidation of H2O2 by the working electrode is balanced by reduction of, for example, ambient oxygen, enzyme-generated H2O2 and other reducible species at the counter electrode. See Fraser, DM, "An Introduction to Invivo Biosensing: Progress and Problems". In "Biosensors and the Body," DM Fraser, ed., 1997, pp. 1-56 John Wiley and Sons, New York.

[0287] In vivo, glucose concentrations are typically about one hundred times or more the concentration of oxygen. Oxygen is therefore the limiting reactant in the electrochemical reaction, and the sensor cannot accurately measure glucose concentration when insufficient oxygen is provided to the sensor. Thus, inhibited sensor function or inaccuracy is believed to be a result of oxygen availability issues to the enzyme and / or electroactive surface.

[0288] Therefore, in an alternative example, an oxygen conduit (e.g., a high oxygen solubility domain formed of silicone or a fluorochemical or perfluorocarbon compound) extending from the ex vivo portion of the sensor to the in vivo portion of the sensor is provided to increase the availability of oxygen to the enzyme. The oxygen conduit may be formed as part of the coating (insulating) material, or may be a separate conduit associated with the wire assembly forming the sensor.

[0289] In some examples, one or more domains of the sensing film are formed of materials such as silicone; polytetrafluoroethylene; polyethylene-co-tetrafluoroethylene; polyolefins; polyesters; polycarbonates; biostable polytetrafluoroethylene; homopolymers, copolymers, terpolymers of polyurethane; polypropylene (PP); polyvinyl chloride (PVC); polyvinylidene fluoride (PVDF); polybutylene terephthalate (PBT); polymethyl methacrylate (PMMA); polyetheretherketone (PEEK); polyurethane; cellulosic polymers; poly(ethylene oxide), poly(propylene oxide) and copolymers and blends thereof; polysulfones and block copolymers thereof, including, for example, diblock copolymers, triblock copolymers, alternating copolymers, random copolymers, and graft copolymers. U.S. Patent Application Publication No. 2005 / 0245799 to Brauker et al., which is incorporated herein by reference in its entirety, describes biointerfaces and sensing film configurations and materials that can be applied to the sensors disclosed herein.

[0290] The sensing film can be deposited on the electroactive surface of the electrode material using known thin or thick film techniques (e.g., spraying, electrodeposition, dipping, etc.) It should be noted that the sensing film surrounding the working electrode does not necessarily have the same structure as the sensing film surrounding the reference electrode, etc. For example, the transduction element domain deposited on the working electrode does not necessarily need to be deposited on the reference electrode and / or the counter electrode.

[0291] In one example, the sensor is an enzyme-based electrochemical sensor, where the working electrode measures hydrogen peroxide produced by the enzyme-catalyzed reaction of glucose being detected and forms a measurable electron current (e.g., glucose is detected using glucose oxidase to produce hydrogen peroxide as a byproduct, and H2O2 reacts with the surface of the working electrode to produce two protons (2H + ), two electrons (2e - ) and an oxygen molecule (O2), thereby producing an electron current being detected), such as described in more detail above and as understood by one of ordinary skill in the art. In some examples, one or more potentiostats are used to monitor the electrochemical reaction at the electroactive surface of the working electrode. The potentiostat applies a constant potential to the working electrode and its associated reference electrode to determine the current generated at the working electrode. The current generated at the working electrode (and flowing through the circuit to the counter electrode) is substantially proportional to the amount of H2O2 diffused to the working electrode. For example, the output signal is typically a raw data stream used to provide a recipient or physician with a usable value of the measured analyte concentration in the recipient, such as a raw signal processed by an algorithm before displaying the value.

[0292] Some alternative analyte sensors that may benefit from the systems and methods of the present disclosure include, for example, U.S. Pat. No. 5,711,861 to Ward et al., U.S. Pat. No. 6,642,15 to Vachon et al., U.S. Pat. No. 6,654,625 to Say et al., U.S. Pat. No. 6,565,509 to Say et al., U.S. Pat. No. 6,514,718 to Heller, U.S. Pat. No. 6,465,66 to Essenpreis et al., U.S. Pat. No. 6,214,625 to Offenbacher et al. ,185, U.S. Patent No. 5,310,469 to Cunningham et al. and U.S. Patent No. 5,683,562 to Shaffer et al., U.S. Patent No. 6,579,690 to Bonnecaze et al., U.S. Patent No. 6,484,46 to Say et al., U.S. Patent No. 6,512,939 to Colvin et al., U.S. Patent No. 6,424,847 to Mastrototaro et al., U.S. Patent No. 6,424,847 to Mastrototaro et al. Each of the above patents is incorporated herein by reference in its entirety and does not include all applicable analyte sensors; in general, it should be understood that the disclosed examples are applicable to a variety of analyte sensor configurations. In other examples of sensor systems including a biointerface / drug release layer, the sensor can be a planar or substantially planar sensor.

[0293] Exemplary Multi-Analyte Sensor Membrane Configurations

[0294] Continuous multi-analyte sensors with various membrane configurations are provided that are suitable for simultaneously, intermittently and / or sequentially facilitating signal transduction corresponding to analyte concentrations. In one example, such sensors can be configured using a signal transducer including one or more transduction elements ("TL"). Such continuous multi-analyte sensors can employ various transduction means, such as amperometry, voltage measurement, potentiometry, and impedance measurement, among other techniques.

[0295] In one example, the transduction element includes one or more membranes, which may include one or more layers and / or domains, each of which may independently include one or more signal transducers, such as enzymes, RNA, DNA, aptamers, binding proteins, etc. As used herein, transduction elements include enzymes, ionophores, RNA, DNA, aptamers, binding proteins, and are used interchangeably.

[0296] In one example, the transduction element is present in one or more membranes, layers or domains formed on the sensing region. In one example, such a sensor can be configured using one or more enzyme domains, such as a membrane domain including enzyme domains, also referred to as an EZ layer ("EZL"), each of which can include one or more enzymes. References to "enzyme layer" below are intended to include all or part of an enzyme domain, any of which can be all or part of a membrane system as discussed herein, such as as a single layer, as two or more layers, as a bilayer pair, or as a combination thereof.

[0297] In one example, the continuous multi-analyte sensor uses one or more of the following analyte-substrate / enzyme pairs: for example, a combination of sarcosine oxidase and creatinine amide hydrolase, the creatinine amide hydrolase being used to sense creatinine. Other examples of analyte / oxidase combinations that can be used in the sensing region include, for example, alcohol / alcohol oxidase, cholesterol / cholesterol oxidase, galactose / galactose oxidase, choline / choline oxidase, glutamate / glutamate oxidase, glycerol / glycerol-3 phosphate oxidase (or glycerol oxidase), bilirubin / bilirubin oxidase, ascorbic acid / ascorbic acid oxidase, uric acid / uric acid oxidase, pyruvate / pyruvate oxidase, hypoxanthine:xanthine / xanthine oxidase, glucose / glucose oxidase, lactate / lactate oxidase, L-amino acid oxidase, and glycine / sarcosine oxidase. Other analyte-substrate / enzyme pairs may be used, including those containing genetically altered enzymes, immobilized enzymes, mediator-linked enzymes, dimerized and / or fusion enzymes.

[0298] NAD-based multi-analyte sensor platform

[0299] Nicotinamide adenine dinucleotide (NAD(P) + NAD(P)H) is a coenzyme, for example a dinucleotide consisting of two nucleotides linked by their phosphate groups. One nucleotide contains an adenine nucleobase and the other contains nicotinamide. NAD exists in two forms, for example an oxidized form (NAD(P)+) and a reduced form (NAD(P)H) (H = hydrogen). The reaction of NAD+ and NADH is reversible, so the coenzyme can be used in NAD(P) + / and NAD(P)H forms without being essentially consumed.

[0300] In one example, one or more enzyme domains of a sensing region of a continuous multi-analyte sensor device disclosed herein include an amount of NAD+ or NADH for providing transduction of a detectable signal corresponding to the presence or concentration of one or more analytes. In one example, one or more enzyme domains of a sensing region of a continuous multi-analyte sensor device disclosed herein include an excess of NAD+ or NADH for providing prolonged transduction of a detectable signal corresponding to the presence or concentration of one or more analytes.

[0301] In one example, NAD, NADH, NAD+, NAD(P)+, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), and functionalized derivatives thereof can be used in combination with one or more enzymes in a continuous multi-analyte sensor device. In one example, NAD, NADH, NAD+, NAD(P)+, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), and functionalized derivatives thereof are bound to a sensing region. In one example, NAD, NADH, NAD+, NAD(P)+, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), and functionalized derivatives thereof are dispersed or distributed in one or more membranes or domains of a sensing region.

[0302] In one aspect of the present disclosure, continuous sensing of one or more or two or more analytes using NAD+ dependent enzymes is provided in one or more membranes or domains of the sensing region. In one example, the membrane or domain provides retention and stable recycling of NAD+ and a mechanism for transducing NADH oxidation or NAD+ reduction into a current measurable by amperometry. In one example, as described below, continuous sensing of multiple analytes is provided, the multiple analytes are reversibly bound or at least one of the analytes is oxidized or reduced by NAD+ dependent enzymes, and the enzymes are, for example, ketones (β-hydroxybutyrate dehydrogenase), glycerol (glycerol dehydrogenase), cortisol (11β-hydroxysteroid dehydrogenase), glucose (glucose dehydrogenase), alcohol (alcohol dehydrogenase), aldehydes (aldehyde dehydrogenase) and lactic acid (lactate dehydrogenase). In other examples, as described below, a membrane is provided that enables continuous, in vivo sensing of multiple analytes using FAD-dependent dehydrogenases (such as fatty acids (acyl-CoA dehydrogenases)).

[0303] An exemplary configuration of one or more membranes or portions thereof is an arrangement for providing retention and recycling of NAD+. Thus, the electrode surface or planar conductive surface of the wire (coaxial) is coated with at least one layer comprising at least one enzyme, such as Figure 1A Depicted. Reference Figure 1B, one or more optional layers may be positioned between the electrode surface and the one or more enzyme domains. For example, one or more interference domains (also referred to as "interferent blocking layers") may be used to reduce or eliminate signal contributions from the presence of undesirable substances, or one or more electrodes (not shown) may be used to assist in wetting, system equilibration, and / or startup. Figure 1A , Figure 1B As shown, one or more membranes in the membrane provide NAD+ reservoir domains, providing a reservoir for NAD+. In one example, one or more interfering substances are used to block the membrane, and a potentiostat is used to measure the H2O2 production or O2 consumption of an enzyme (such as or similar to NADH oxidase), and the NAD+ reservoir and enzyme domain positions can be switched to promote better consumption of excess NAD+ and slower unnecessary outward diffusion. Exemplary sensor configurations can be found in U.S. Provisional Patent Application No. 63 / 321340 filed on March 18, 2022, "CONTINUOUS ANALYTE MONITORING SENSOR SYSTEMS AND METHODS OF USING THESAME"", the entire contents of which are incorporated herein by reference; and in U.S. Provisional Patent Application No. 63 / 291726 filed on December 20, 2021, "MEDIATOR-TETHERED NAD(H)FOR KETONE SENSING", the entire contents of which are incorporated herein by reference.

[0304] In one example, one or more mediators that are best for NADH oxidation are bound to one or more electrode domains or enzyme domains. In one example, an organic mediator is used, such as phenanthroline dione or nitrosoaniline. In another example, a metal organic mediator is used, such as ruthenium-phenanthroline-dione or osmium (bpy) 2Cl, a polymer or an organometallic coordination mediator polymer containing a covalently coupled organic mediator, such as polyvinyl imidazole-Os (bpy) 2Cl, or polyvinyl pyridine-organometallic coordination mediator (including ruthenium-phenanthroline dione). As discussed further below, other mediators can be used.

[0305] In humans, serum levels of beta-hydroxybutyrate (BHB) are typically in the low micromolar range, but can rise to about 6mM to 8mM. Serum levels of BHB can reach 1mM to 2mM after intense exercise, or reach a stable level of more than 2mM through a ketogenic diet with almost no carbohydrates. Other ketones, such as acetoacetate and acetone, are present in serum, however, most of the dynamic range of ketone levels is in the form of BHB. Therefore, monitoring (e.g., continuous monitoring) of BHB is useful for providing health information to users or medical providers.

[0306] Thus, exemplary continuous ketone analyte detection using an electrode-associated mediator / NAD+ / dehydrogenase (e.g., β-hydroxybutyrate dehydrogenase (HBDH)) for continuous monitoring of BHB is provided. In one example, Fig.21A A continuous ketone sensor configuration capable of monitoring BHB is depicted in which a mediator / NAD+ / dehydrogenase is present adjacent to an electrode surface 198. Alternatively, for example, multiple enzyme domains may be used in an enzyme layer, wherein the layer including the mediator / NAD+ is closer to the electrode surface than the adjacent enzyme domain including the dehydrogenase. In one example, NAD+ and / or HBDH are present in the same or different enzyme domains, and any of them may be immobilized, for example, using an amine-reactive crosslinker (e.g., glutaraldehyde, epoxide, NHS ester, imidate). In one example, NAD+ is coupled to a polymer and is present in an enzyme domain that is the same or different from HBDH. In one example, the molecular weight of NAD+ is increased to prevent or reduce migration from the sensing region, such as using the C6 terminal amine of NAD+ to dimerize NAD+ with any amine-reactive crosslinker, and NAD+ is fixed to the polymer from its C6 terminal amine. In one example, a mediator polymer containing an organic mediator or an organometallic coordinated mediator polymer is used, which is covalently or otherwise operably coupled to an electrode. In other examples, NAD+ can be electrografted to an electroactive surface (e.g., a working electrode). In one example, the electrografted NAD+ is enzymatically active. In another example, the electrografted NAD+ is not enzymatically active.

[0307] In some examples, the flux of reactants / co-reactants (such as oxygen) through the sensing region has little effect (if any) on the transduction signal. In the above configuration, there is no consumption of oxygen or generation of hydrogen peroxide, but there is a direct transfer of electrons from the enzyme to the electrode surface for signal transduction. Therefore, despite the presence of endogenous electroactive substances such as ascorbate and urate, the need to preferentially weaken the analyte flux relative to such other reactants such as oxygen and peroxide is reduced or eliminated. For example, a uniform polymer with a controlled mesh size can be used. In other examples, the sensing region includes one or more oxygen-dependent enzymes, and the oxygen flux is maximized, for example, including silicone, polysiloxane or copolymers. Other membranes can be used, for example, between or on the above-mentioned EZL or NAD+ reservoirs, such as drug release and / or biointerface layers.

[0308] Another example of a continuous ketone analyte detection configuration using a mediator-coupled diaphorase / NAD+ / dehydrogenase associated with electrode surface 198 is Fig.21B Depicted in.

[0309] In one example, diaphorase is electrically coupled to an electrode having an organometallic coordination mediator polymer. In another example, diaphorase is covalently coupled to an electrode having an organometallic coordination mediator polymer.

[0310] Alternatively, multiple enzyme domains may be used in the enzyme layer, for example, to separate the electrode-associated diaphorase (closest to the electrode surface) from the more distally adjacent NAD+ or dehydrogenase to substantially separate NADH oxidation from analyte (ketone) oxidation. Alternatively, NAD+ may be closer to the electrode surface than an adjacent enzyme domain including a dehydrogenase. In one example, NAD+ and / or HBDH are present in the same or different enzyme domains, and either of them may be immobilized, for example, using an amine-reactive crosslinker (e.g., glutaraldehyde, epoxide, NHS ester, imidate). In one example, NAD+ is coupled to a polymer and is present in the same or different enzyme domain as HBDH. In one example, the molecular weight of NAD+ is increased to prevent or eliminate migration from the sensing region, for example, using the C6 terminal amine of NAD+ to dimerize NAD+ with any amine-reactive crosslinker. In one example, NAD+ can be covalently coupled to an aspect of an enzyme domain that has a higher molecular weight than NAD+, which can improve the stability profile of NAD+ and thereby improve the ability to retain and / or immobilize NAD+ in the enzyme domain. For example, dextran-NAD.

[0311] In yet another example, Fig. 21C As shown, oxidation of NADH oxidase to form hydrogen peroxide at electrode surface 198 can be used as a signal transduction substance to provide a transduction signal from a transduction element of a continuous ketone (and one or more other analytes) sensor configuration. In this configuration, an electrode surface 198, membrane, layer or domain can be used that selectively reduces the flux of analyte and NAD+ while allowing a high flux of oxygen to enter the sensing area. Thus, one or more interference domains, such as NAFION TM or alternating layers of polyallylamine and polyacrylic acid, etc. In one example, HBDH and one or more other analyte-specific oxidases are present in the same or different enzyme domains and can be immobilized.

[0312] In one example, NAD+ is coupled to or uncoupled from the polymer or physically trapped therein and is present in the same or different enzyme domain as HBDH. In one example, the molecular weight of NAD+ is increased to prevent or eliminate migration from the sensing region, such as using the C6 terminal amine of NAD+ and any amine-reactive crosslinking agent to dimerize NAD+. In one example, superoxide dismutase (SOD) can be included in this configuration, for example, in the same enzyme domain as NADH, for scavenging free radicals produced by NADH oxidase and thus improving signal stability and sensor performance. In the above configuration, the transduced signal is oxygen-dependent, and the oxygen flux is maximized, for example, using a homogeneous polymer film having a controlled mesh size and / or including silicone, polysiloxane or copolymers in one or more enzyme domains. In one example, where the signal is non-oxygen-dependent, a resistance domain is used to weaken the flux of the analyte entering the EZL so that the sensor response remains linear over the entire physiological range of the target analyte. The "target" analyte discussed herein is an analyte intended to be detected by the sensor system discussed herein. One or more target analytes can be detected and analyzed using the sensor systems discussed herein.

[0313] In one example, the sensing region includes one or more NADH:acceptor oxidoreductases and one or more NAD-dependent dehydrogenases. In one example, the sensing region includes one or more NADH:acceptor oxidoreductases and one or more NAD(P)-dependent dehydrogenases, wherein NAD(P)+ or NAD(P)H is present as a cofactor in the sensing region. In one example, the sensing region includes an amount of diaphorase.

[0314] In one example, a ketone sensing configuration suitable for combination with another analyte sensing configuration is provided. Thus, by combining a 10 mM analyte with about 20 μL of 500 mg / mL HBDH, about 20 μL of [500 mg / mL NAD(P)H, 200 mg / mL of about 400 MW polyethylene glycol-diethylene glycol ether (PEG-DGE)], about 20 μL of 500 mg / mL diaphorase, about 40 μL of 250 mg / mL polyvinyl imidazole-osmium bis(2,2′-bipyridyl) chloride (PVI-Os(bpy)2Cl), and about 10 mM The composition of the EZL solution of HEPES in water is provided to a substrate such as a working electrode to prepare an EZL layer of about 1 μm to 20 μm thick to provide about 15 wt% to 40 wt% HBDH, about 5% to 30% diaphorase, about 5% to 30% NAD(P)H, about 10% to 50% PVI-Os(bpy)2Cl, and about 1% to 12% PEG-DGE (400 MW) after drying. The substrate discussed herein, which may include a working electrode, may be formed of gold, platinum, palladium, rhodium, iridium, titanium, tantalum, chromium, and / or alloys or combinations thereof or carbon (e.g., graphite, glassy carbon, carbon nanotubes, graphene, or doped diamond, and combinations thereof).

[0315] A resistive domain (also referred to as a resistive layer ("RL")) is contacted with the enzyme domain described above. In one example, the RL includes about 55% to 100% polyvinylpyrrolidone (PVP) and about 0.1% to 45% PEG-DGE. In another example, the RL includes about 75% to 100% PVP and about 0.3% to 25% PEG-DGE. In yet another example, the RL includes about 85% to 100% PVP and about 0.5% to 15% PEG-DGE. In yet another example, the RL includes substantially 100% PVP.

[0316] like Figure 1A , Figure 1BThe depicted exemplary continuous ketone sensor including NAD (P) H reservoir domain is configured so that NAD (P) H is not rate-limiting in any enzyme domain in the enzyme domain of the sensing region. In one example, the loading of NAD (P) H in the NAD (P) H reservoir domain is greater than about 20 wt%, 30 wt%, 40 wt% or 50 wt%. The portion of one or more membranes or one or more membrane domains in the membrane (hereinafter also referred to as "membrane") may also contain polymer or protein binders, such as zwitterionic polyurethane and / or albumin. Alternatively, in addition to NAD (P) H, the membrane may also contain one or more analyte-specific enzymes (e.g., HBDH, glycerol dehydrogenase, etc.) so that, optionally, the NAD (P) H reservoir membrane also provides catalytic function. In one example, NAD (P) H is dispersed or distributed in a polymer (or protein) or dispersed or distributed together with a polymer (or protein), and may be cross-linked to still allow enough enzyme / cofactor functionality and / or reduce the degree of NAD (P) H flux in the domain.

[0317] In one example, NADH oxidase, alone or in combination with superoxide dismutase (SOD), is used in one or more membranes of the sensing region. In one example, superoxide dismutase (SOD) is used in an amount capable of scavenging some or most of the one or more free radicals generated by NADH oxidase. In one example, NADH oxidase, alone or in combination with superoxide dismutase (SOD), is used in combination with NAD(P)H and / or a functionalized polymer, wherein NAD(P)H is immobilized to the polymer from the C6 terminal amine in one or more membranes of the sensing region.

[0318] In one example, NAD(P)H is immobilized to a degree that maintains the catalytic functionality of NAD(P)H. In one example, dimerized NAD(P)H is used to trap NAD(P)H within one or more membranes by cross-linking their respective C6 terminal amines with an appropriate amine-reactive cross-linker such as glutaraldehyde or PEG-DGE or polycarbodiimide cross-linkers.

[0319] The foregoing continuous ketone sensor configuration can be adapted for use with other analytes or in combination with other sensor configurations. For example, analyte-dehydrogenase combinations can be used in any of the membranes in the sensing region, including: glycerol (glycerol dehydrogenase); cortisol (11β-hydroxysteroid dehydrogenase); glucose (glucose dehydrogenase); alcohol (alcohol dehydrogenase); aldehyde (aldehyde dehydrogenase); and lactate (lactate dehydrogenase).

[0320] In one example, a semipermeable membrane is used in or adjacent to the sensing region or adjacent to one or more membranes of the sensing region to reduce the flux of at least one analyte or chemical substance. In one example, the semipermeable membrane reduces the flux of at least one analyte or chemical substance to provide a linear response from the transduction signal. In another example, the semipermeable membrane prevents or eliminates NAD (P) H from flowing out of the sensing region or any membrane or domain. In one example, the semipermeable membrane can be an ion selective membrane that is selective for an ionic analyte of interest, such as ammonium ions.

[0321] In another example, a continuous multi-analyte sensor configuration including one or more enzymes and / or at least one cofactor is prepared. Figure 1C This exemplary configuration of an enzyme domain 150 is depicted, the enzyme domain including an enzyme (Enzyme) having a certain amount of cofactor (Cofactor), the enzyme domain being positioned near at least a portion of a working electrode ("WE") surface, wherein the WE includes an electrochemical reaction surface. In one example, a second membrane 151 including a certain amount of cofactor is positioned adjacent to the first enzyme domain. A certain amount of cofactor in the second membrane can provide an excess to the enzyme, for example to extend the life of the sensor. One or more resistance domains 152 ("RL") are positioned adjacent to the second membrane (or may be positioned between the membranes). The RL may be configured to block the diffusion of the cofactor from the second membrane. The electron transfer transduction from the cofactor to the WE directly or indirectly corresponds to a signal of the analyte concentration.

[0322] Figure 1D An alternative enzyme domain configuration is depicted, comprising a first membrane 151 having an amount of cofactor, the first membrane being positioned closer to at least a portion of the WE surface.An enzyme domain 150 comprising an amount of enzyme is positioned adjacent to the first membrane.

[0323] exist Figure 1C , Figure 1D In the depicted membrane structure, the generation of electrochemically active species in the enzyme domain diffuses to the WE surface and transduces a signal corresponding directly or indirectly to the concentration of the analyte. In some examples, the electrochemically active species includes hydrogen peroxide. For sensor configurations including cofactors, the cofactor from the first layer can diffuse to the enzyme domain to extend the sensor life, for example by regenerating the cofactor. For other sensor configurations, the cofactor can be optionally included to improve performance attributes, such as stability. For example, a continuous ketone sensor can include NAD(P)H and a divalent metal cation, such as Mg +2 . One or more resistor domains RL may be positioned adjacent to the second membrane (or may be positioned between layers). The RL may be configured to block diffusion of cofactors from the second membrane and / or interferents from reaching the WE surface. Other configurations may be used in the aforementioned configurations, such as electrodes, resistors, biointerfaces, and drug release membranes, layers, or domains. In other examples, the continuous analyte sensor includes one or more cofactors that contribute to sensor performance.

[0324] Figure 1E Another continuous multi-analyte membrane configuration is depicted, wherein the {β}-hydroxybutyrate dehydrogenase BHBDH in the first enzyme domain 153 is positioned near the working electrode WE, and the second enzyme domain 154, for example, including alcohol dehydrogenase (ADH) and NADH, is positioned adjacent to the first enzyme domain. One or more resistance domains RL 152 can be deployed adjacent to the second enzyme domain 154. In this configuration, the presence of a combination of alcohol and ketones in serum works together to provide a transduction signal corresponding to at least one analyte concentration (e.g., ketone) in the analyte concentration. Therefore, when the NADH present in the more distal second enzyme domain consumes the alcohol present in the serum environment, the NADH is oxidized to NAD (P) H, which diffuses into the first membrane layer to provide BHBDH-catalyzed electron transfer of acetoacetate ketone and transduction of a detectable signal corresponding to the ketone concentration. In one example, the enzyme can be configured for reverse catalysis, and a substrate for catalyzing another enzyme present in the same or different layer or domain can be generated. Other configurations can be used in the aforementioned configurations, such as electrodes, resistors, biointerfaces, and drug release membranes, layers, or domains. Thus, a first enzyme domain that is further away from the WE than a second enzyme domain can be configured to generate a cofactor or other element to serve as a reactant (and / or reactant substrate) for the second enzyme domain to detect one or more target analytes.

[0325] Combinations of the above configurations may be employed. Figure 1F , Figure 1G Experimental data and linear regression are depicted, respectively, for an exemplary continuous ketone sensor configuration over the ketone range of 0 mM to 8 mM, and provide a continuous, linear response and signal stability (ex vivo).

[0326] Figure 1H , Fig. 1I and Figure 1J Experimental data (0 mM to 5 mM ketone) are depicted, demonstrating sensitivity, calibration, and drift (20 hours at 5 mM) of an exemplary continuous ketone sensor configuration using NAD+ cofactor and NADH oxidase 170, 172 from different natural sources, respectively, and demonstrating continuous, linear response and signal stability. Figures 1H to 1J The data shown in 199 represent samples without cofactor (BHBDH only). In one example, a mutant NAD+ cofactor is used to improve retention of the cofactor in one or more membranes, providing improved covalent or non-covalent binding of the cofactor to one or more membranes of a continuous ketone sensor.

[0327] Alcohol sensor configuration

[0328] In one example, a continuous alcohol (e.g., ethanol) sensor device configuration is provided. In one example, one or more enzyme domains including an alcohol oxidase (AOX) are provided, and the presence and / or amount of alcohol is transduced by producing hydrogen peroxide alone or in combination with oxygen consumption or with another substrate-oxidase system (e.g., glucose-glucose oxidase), wherein hydrogen peroxide and / or oxygen and / or glucose can be qualitatively or quantitatively detected and / or measured using amperometry.

[0329] In one example, the sensing area for the aforementioned substrate-oxidase configuration has one or more enzyme domains, including one or more electrodes. In one example, the sensing area for the aforementioned substrate-oxidase configuration has one or more enzyme domains, which have or do not have one or more electrodes, and also includes one or more interference blocking membranes (such as selective permeability membranes, charge exclusion membranes) to weaken one or more interferers to diffuse to the working electrode through the membrane. In one example, the sensing area for the aforementioned substrate-oxidase configuration has one or more enzyme domains, which have or do not have one or more electrodes, and also includes one or more resistance domains, which have or do not have one or more interference blocking membranes to weaken one or more analytes or enzyme substrates. In one example, the sensing area for the aforementioned substrate-oxidase configuration has one or more enzyme domains, which have or do not have one or more electrodes, and one or more resistance domains with or without one or more interference blocking membranes also independently include one or more biointerface membranes and / or drug release membranes to weaken one or more analytes or enzyme substrates and weaken the immune response of the recipient after insertion.

[0330] In one example, one or more interference blocking films are deposited adjacent to the working electrode and / or electrode surface. In one example, one or more interference blocking films are deposited directly adjacent to the working electrode and / or electrode surface. In one example, one or more interference blocking films are deposited between another layer or film or domain adjacent to the working electrode or electrode surface to reduce the diffusion of one or all analytes other than oxygen through the sensing area. Such films can be used to reduce the alcohol itself and reduce other electrochemically active substances or other analytes, which, if diffused to the working electrode, may interfere in other ways by generating signals.

[0331] Figure 2 Depicted are experimental data from a non-limiting example of an alcohol sensor that includes an alcohol oxidase in one or more layers coated with one or more interfering membranes. In one example, the working electrode used includes platinum and the applied potential is about 0.5 volts. Figure 2 Shown are signal responses (amperes) over time (seconds) with stepwise addition of alcohol at ethanol concentrations ranging from 0 mg / dL to 200 mg / dL. Figure 2Substantial linearity of the current response over at least a portion of the pharmacological range in humans from 1 mg / dL to about 200 mg / dL is shown.

[0332] In one example, electrochemical sensing of oxygen level changes can be accomplished, for example, by using one or more polymers such as NAFION TM ) is performed using one or more membrane coated electrodes. Based on the change in potential, changes in oxygen concentration can be recorded, which are directly or indirectly related to the concentration of alcohol. When properly designed to obey stoichiometric behavior, the presence of a specific concentration of alcohol should cause a commensurate reduction in local oxygen that is directly (linearly) related to the alcohol concentration. Therefore, a multi-analyte sensor for both alcohol and oxygen can be provided.

[0333] In another example, the alcohol sensing configuration mentioned above may include one or more secondary enzymes that react with the reaction product catalyzed by the alcohol / alcohol oxidase (e.g., hydrogen peroxide) and provide an oxidized form of the secondary enzyme that transduces the alcohol-dependent signal to the WE / RE at a lower potential than without the secondary enzyme. Thus, in one example, the alcohol / alcohol oxidase is used together with a reduced form of a peroxidase (e.g., horseradish peroxidase). The alcohol / alcohol oxidase may be in the same or different layer as the peroxidase, or they may be spatially separated away from the electrode surface, for example, the alcohol / alcohol oxidase is further away from the electrode surface and the peroxidase is closer to the electrode surface, or alternatively, the alcohol / alcohol oxidase is closer to the electrode surface and the peroxidase is further away from the electrode surface. In one example, the alcohol / alcohol oxidase is further away from the electrode surface and the peroxidase also includes any combination of electrodes, interference, resistors, and biointerface films to optimize signal, durability, reduce drift, or extend service life.

[0334] In another example, the alcohol sensing configuration mentioned above may include one or more mediators. In one example, one or more mediators are present in, on or around one or more electrodes or electrode surfaces, and / or are deposited on the surface of a working electrode (WE) or a reference electrode (RE) or otherwise associated therewith. In one example, one or more mediators eliminate or reduce the direct oxidation of interfering substances that may reach WE or RE. In one example, one or more mediators provide a reduction in the operating potential of WE / RE on a platinum electrode, such as from about 0.6V to about 0.3V or lower, which can reduce or eliminate the oxidation of endogenous interfering substances. Examples of one or more mediators are provided below. Other electrodes, such as counter electrodes, may be used.

[0335] In one example, other enzymes or additional components may be added to the polymer mixture that constitutes any portion of the sensing region to increase the stability of the aforementioned sensor and / or reduce or eliminate byproducts of the alcohol / alcohol oxidase reaction. Increasing stability includes storage or shelf life and / or operational stability (e.g., retaining enzyme activity during use). For example, byproducts of an enzyme reaction may be undesirable for increasing shelf life and / or operational stability, and therefore may be desirable to reduce or remove. In one example, xanthine oxidase can be used to remove byproducts of one or more enzyme reactions.

[0336] In another example, a dehydrogenase is used with an oxidase to detect alcohol alone or in combination with oxygen. Thus, in one example, an alcohol dehydrogenase is used to oxidize an alcohol to an aldehyde in the presence of reduced nicotinamide adenine dinucleotide (NAD(P)H) or reduced nicotinamide adenine dinucleotide phosphate (NAD(P)+). In order to provide a continuous source of NAD(P)H or NAD(P)+, an NADH oxidase or NADPH oxidase is used to oxidize NAD(P)H or NAD(P)+ while consuming oxygen. In another example, diaphorase may be used in place of or in combination with NADH oxidase or NADPH oxidase. Alternatively, excess NAD(P)H may be incorporated into one or more enzyme domains and / or one or more electrodes in an amount that accommodates the expected duration of the planned life of the sensor.

[0337] In the aforementioned dual enzyme configuration, the signal can be sensed by any of the following means: (1) electrically coupled (e.g., "wired") alcohol dehydrogenase (ADH), for example using an electroactive hydrogel polymer including one or more mediators; or (2) oxygen electrochemical sensing to measure oxygen consumption by NADH oxidase. In an alternative example, the cofactor NAD(P)H or NAD(P)+ can be coupled to a polymer such as dextran, which is immobilized in the enzyme domain along with the ADH. This provides retention of the cofactor and its availability to the ADH active site. In the above examples, any combination of electrodes, interferences, resistors, and biointerface membranes can be used to optimize signal, durability, reduce drift, or extend service life. In one example, electrical coupling is provided, for example via covalent or ionic bonds, directly or indirectly to at least a portion of a transduction element (such as an aptamer, enzyme, or cofactor) and at least a portion of an electrode surface. Chemical moieties capable of assisting the transfer of electrons from an enzyme or cofactor to an electrode surface can be used, including one or more mediators as described below.

[0338] In one example, any of the foregoing continuous alcohol sensor configurations is combined with any of the foregoing continuous ketone monitoring configurations to provide a continuous multi-analyte sensor device as further described below. In one example, a continuous glucose monitoring configuration is combined with any of the foregoing continuous alcohol sensor configurations and any of the foregoing continuous ketone monitoring configurations to provide a continuous multi-analyte sensor device as further described below.

[0339] Uric acid sensor configuration

[0340] In another example, a continuous uric acid sensor device configuration is provided. Therefore, in one example, urate oxidase (UOX) may be included in one or more enzyme domains and positioned adjacent to the working electrode surface. The catalysis of uric acid using UOX produces hydrogen peroxide, which can be detected using techniques such as amperometry, voltage determination, and impedance determination. In one example, in order to reduce or eliminate interference from direct oxidation of uric acid on the electrode surface, one or more electrodes, interferences, and / or resistance domains may be deposited on at least a portion of the working electrode surface. Such membranes can be used to reduce the diffusion of uric acid and other analytes to the working electrode, which can interfere with signal transduction.

[0341] Figure 3A , Figure 3B Experimental data from a continuous uric acid sensor configuration is shown. In this example, a platinum working electrode is coated with at least one interference membrane, on which there is at least one enzyme domain including UOX. The enzyme domain is covered with one or more resistance domains to control or attenuate the diffusion characteristics. Figure 3A As shown, the exemplary sensor exhibits sensitivity in the physiological concentration range with stability to drift (at 37°C; Figure 3B Shown 14 days at 8 mg / dl UA with high repeatability.

[0342] In an alternative example, the uric acid continuous sensing device configuration includes sensing changes in oxygen levels around the WE surface, for example, as in a Clark-type electrode setup, or one or more electrodes may independently include one or more different polymers, such as NAFION adjacent to at least a portion of the electrode surface. TM , zwitterionic polymers or polymer mediators. In one example, an electrode surface having one or more electrode domains provides operation of measuring oxygen at different or lower voltages. Oxygen levels and changes therein can be sensed, recorded and correlated with uric acid concentrations, for example, using conventional calibration methods.

[0343] In one example, alone or in combination with any of the aforementioned configurations, uric acid sensor configurations, in order to reduce the potential at the WE for uric acid signal transduction, one or more coatings may be deposited on the WE surface. Various techniques can be used, including but not limited to impregnation, electrodeposition, vapor deposition, spraying, etc., to deposit or form one or more coatings on the WE surface and / or other coatings formed thereon. In one example, the coated WE surface can provide a redox reaction such as hydrogen peroxide at a lower potential (compared to 0.6V on the surface of a platinum electrode without such a coating). Examples of materials that can be coated or annealed on the WE surface include but are not limited to Prussian blue, Medola blue, methylene blue, methylene green, methyl viologen, ferrocyanide, ferrocene, cobalt ions, and cobalt phthalocyanine, etc.

[0344] Reference Figure 3C , shows a graphic representation of signal transduction of uric acid with bare or coated electrodes in the presence of added hydrogen peroxide. In the figure, the addition of hydrogen peroxide is detected by all electrodes. However, in contrast to (a) platinum electrodeposited with Prussian blue, (b) gold electrodeposited with Prussian blue, and (c) carbon electrodeposited with Prussian blue, the addition of uric acid is detected at the "bare" platinum electrode (d), indicating the selectivity of this electrode / enzyme domain configuration. In the above examples, any combination of electrodes, interferences, resistors, and biointerface membranes can be arranged to further optimize signal, durability, reduce drift, or extend service life.

[0345] In one example, one or more secondary enzymes, cofactors and / or mediators (electrically coupled or polymeric mediators) can be added to an enzyme domain with UOX to facilitate direct or indirect electron transfer to WE. For example, in such a configuration, regeneration of the initial oxidized form of the secondary enzyme is reduced by WE for signal transduction. In one example, the secondary enzyme is horseradish peroxidase (HRP).

[0346] Choline sensor configuration

[0347] In one example, a continuous choline sensor device can be provided, for example, using a choline oxidase that generates hydrogen peroxide as choline is oxidized. Thus, in one example, at least one enzyme domain includes a choline oxidase (COX) adjacent to at least one WE surface, optionally with one or more electrodes and / or interference membranes positioned between the WE surface and at least one enzyme domain. Catalysis of choline using COX results in the generation of hydrogen peroxide, which can be detected using techniques such as amperometry, voltage measurement, and impedance measurement.

[0348] Figure 4Experimental data showing an operational choline sensor configuration. In this example, a first enzyme domain is formed on one or more interference membranes adjacent to a platinum WE. The first enzyme domain includes choline oxidase, which is covered with one or more resistance domains to control diffusion properties. The data show that the choline sensor can provide sensitivity over a physiological concentration range, with thermal operational stability to drift (37°C), and high repeatability.

[0349] In one example, the aforementioned continuous choline sensor configuration is combined with any of the aforementioned continuous alcohol sensor configuration and continuous uric acid sensor configuration to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capabilities. Other membranes may be used in the aforementioned continuous choline sensor configuration, such as electrodes, resistors, biointerfaces, and drug release membranes.

[0350] Cholesterol sensor configuration

[0351] In one example, a continuous cholesterol sensor configuration can be made using cholesterol oxidase (CHOX) in a manner similar to the sensors previously described. Thus, one or more enzyme domains including CHOX can be positioned adjacent to at least one WE surface. Catalysis of free cholesterol using CHOX results in the generation of hydrogen peroxide, which can be detected using techniques such as amperometry, voltage measurement, and impedance measurement.

[0352] An exemplary cholesterol sensor configuration using platinum WE was prepared, wherein at least one interfering membrane was positioned adjacent to at least one WE surface, upon which at least one enzymatic domain including CHOX was present, and upon which at least one resistive domain was positioned to control diffusion properties. Figure 5 Data demonstrating that the above-described cholesterol sensor configuration can provide sensitivity in the physiological concentration range, with thermal operational stability to drift (37° C.), and high reproducibility are depicted.

[0353] The above method and the cholesterol sensor can measure free cholesterol, however, by modification, the configuration can measure more types of cholesterol and total cholesterol concentration. It is important to measure different types of cholesterol and total cholesterol because a significant amount of cholesterol is in unmodified and esterified form due to the low solubility of cholesterol in water. Therefore, in one example, a total cholesterol sample is provided, wherein a secondary enzyme is introduced into at least one enzyme domain, for example, to provide a combination of cholesterol esterase and CHOX cholesterol ester, which essentially represents the total cholesterol that can be indirectly measured from the signal transduced by the cholesterol present and formed by the esterase.

[0354] In one example, the aforementioned continuous (total) cholesterol sensor configuration is combined with any of the aforementioned continuous alcohol sensor configurations and / or continuous uric acid sensor configurations to provide a continuous multi-analyte sensor system as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capabilities. Other membrane configurations may be used in the aforementioned continuous cholesterol sensor configuration, such as one or more electrode domains, resistor domains, biointerface domains, and drug release membranes.

[0355] Bilirubin sensor and ascorbic acid sensor configuration

[0356] In one example, continuous bilirubin and ascorbic acid sensors are provided. These sensors can use bilirubin oxidase and ascorbic acid oxidase, respectively. However, unlike some oxidoreductases, the final product of the catalysis of the analyte of bilirubin oxidase and ascorbic acid oxidase is water rather than hydrogen peroxide. Therefore, it is impossible to associate the redox detection of hydrogen peroxide with bilirubin or ascorbic acid. However, these oxidases still consume oxygen for catalysis, and the level of oxygen consumption is related to the level of the target analyte present. Therefore, bilirubin and ascorbic acid levels can be indirectly measured by electrochemically sensing changes in oxygen levels, such as in a Clark-type electrode arrangement.

[0357] Alternatively, different configurations for sensing bilirubin and ascorbic acid may be employed. For example, an electrode domain comprising one or more electrode domains may be coated on the electrode, the one or more electrode domains comprising a NAFION TM , zwitterionic polymers or polymer mediators. The measured oxygen level transduced from such an enzyme domain configuration can be correlated with the bilirubin concentration and the ascorbic acid level. In one example, an electrode domain including one or more mediators electrically coupled to a working electrode can be used, and the electrode domain can be correlated with the bilirubin level and the ascorbic acid level.

[0358] In one example, the aforementioned continuous bilirubin and ascorbic acid sensor configuration can be combined with any of the aforementioned continuous alcohol sensor configuration, continuous uric acid sensor configuration, and continuous cholesterol sensor configuration to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device can also include continuous glucose monitoring capabilities. Other membranes can be used in the aforementioned continuous bilirubin and ascorbic acid sensor configuration, such as electrodes, resistors, biointerfaces, and drug release membranes.

[0359] Single working electrode configuration for dual analyte detection

[0360] In one example, at least a dual enzyme domain configuration is provided, wherein each layer contains one or more specific enzymes and optionally one or more cofactors. In a broad sense, an example of a continuous multi-analyte sensor configuration is depicted in Fig. 6A155 (EZL1) comprising at least one enzyme (enzyme 1) in at least two enzyme domain configurations is close to at least one surface of the WE. One or more analyte-substrate enzyme pairs with enzyme 1 transduce at least one detectable signal to the WE surface by direct electron transfer or by mediated electron transfer corresponding directly or indirectly to the analyte concentration. A second membrane 156 (EZL2) with at least one second enzyme (enzyme 2) is positioned adjacent to 155ELZ1 and is generally further away from the WE than EZL1. One or more resistance domains (RL) 152 may be provided adjacent to EZL2 156 and / or between EZL1 155 and EZL2 156. Different enzymes catalyze the conversion of the same analyte, but at least one enzyme in EZL2 156 provides hydrogen peroxide, and at least one other enzyme in EZL1 155 does not provide hydrogen peroxide. Therefore, each measurable substance (e.g., hydrogen peroxide and other measurable substances that are not hydrogen peroxide) generates a signal associated with its concentration.

[0361] For example, in Fig. 6A In the configuration shown, a first analyte diffuses through RL 152 and enters EZL2 156, generating peroxide via interaction with Enzyme 2. The peroxide diffuses to the WE through at least EZL1 155 and transduces a signal corresponding directly or indirectly to the concentration of the first analyte. A second analyte different from the first analyte diffuses through RL 152 and EZL2 156 and interacts with Enzyme 1, which results in electron transfer to the WE, and transduces a signal corresponding directly or indirectly to the concentration of the second analyte.

[0362] like Figure 6B As shown, the above configuration is adapted for use in a wire electrode configuration, wherein at least two different enzyme-containing layers are configured on the same WE having a single active surface. In one example, the single WE is a wire, wherein the active surface is positioned around the longitudinal axis of the wire. In another example, the single WE is a conductive trace on a substrate, wherein the active surface is positioned around the longitudinal axis of the trace. In one example, the active surface is substantially continuous around the longitudinal axis or radius.

[0363] In the above configuration, at least two different enzymes may be used and catalyze conversion of different analytes, wherein at least one enzyme in EZL2 156 provides hydrogen peroxide and at least another enzyme in EZL1 155 does not provide hydrogen peroxide, for example providing electron transfer to the WE surface that directly or indirectly corresponds to the analyte concentration.

[0364] In one example, the inner layer of at least two enzyme domains EZL1 155, EZL2 156 includes at least one immobilized enzyme in combination with at least one mediator that facilitates lower bias operation of the WE than without the mediator. In one example, for such direct electron transduction, potential P1 is used. In one example, at least a portion of the inner layer EZL1 155 is closer to the WE surface and may have one or more intervening electrode domains and / or cover interference and / or biological interface and / or drug release membrane, provided that at least one mediator facilitates low bias operation of the WE surface. In another example, at least a portion of the inner layer EZL1 155 is directly adjacent to the WE.

[0365] Figure 6B The second layer (outer layer EZL2 156) of at least the double enzyme domain contains at least one enzyme, which leads to one or more catalytic reactions, which ultimately generate a certain amount of hydrogen peroxide, which can electrochemically transduce a signal corresponding to the concentration of the analyte. In one example, the generated hydrogen peroxide diffuses through the layer EZL2 156 and through the inner layer EZL1155 to reach the WE surface and undergoes redox at the potential of P2, where P2≠P1. In this way, by controlling the potentials P1 and P2 applied at the same WE surface, electron transfer and electrolysis (redox) can be selectively controlled. Any applied potential duration can be used for P1 and P2, such as equal / periodic duration, staggered duration, random duration, and various potential determination sequences, cyclic voltammetry, etc. In some examples, impedance measurement sensing can be used. In one example, a phase shift (e.g., time delay) can be generated due to the detection of two signals from two different working electrodes, each signal being generated by a different EZL (EZL1 155, EZL2 156) associated with each electrode. The two (or more) signals can be decomposed into components to detect individual signals and signal artifacts generated by each of EZL1 155 and EZL2 156 in response to detection of two analytes. In some examples, each EZL detects a different analyte. In other examples, both EZLs detect the same analyte.

[0366] In another alternative exemplary configuration, Figure 6C , Fig.6DAs shown, a multi-enzyme domain configuration as described above is provided for a continuous multi-analyte sensor device using a single WE with two or more active surfaces. In one example, the multi-enzyme domain configuration discussed herein is formed on a planar substrate. In another example, a single WE is coaxial, for example, configured as a wire, having two or more active surfaces positioned around the longitudinal axis of the wire. Additional wires can be used, for example, as reference electrodes and / or counter electrodes. In another example, a single WE is a conductive trace on a substrate, wherein two or more active surfaces are positioned around the longitudinal axis of the trace. At least a portion of the two or more active surfaces is discontinuous, thereby providing at least two physically separated WE surfaces (e.g., WE1, WE2) on the same WE wire or trace. In one example, the first analyte detected by WE1 is glucose, and the second analyte detected by WE2 is lactate. In another example, the first analyte detected by WE1 is glucose, and the second analyte detected by WE2 is ketone.

[0367] therefore, Figure 6C , Fig.6D An exemplary configuration of a continuous multi-analyte sensor construction is depicted in which EZL1 155, EZL2 156, and RL 152 (resistance domain) as described above are arranged on a single coaxial wire including spatially separated electrode surfaces WE1, WE2, for example by a sequential dip coating technique. One or more parameters of the enzyme domain, the resistance domain, etc., such as thickness, length along the axis from the distal end of the wire, etc., can be independently controlled along the longitudinal axis of the WE. In one example, at least a portion of the spatially separated electrode surfaces have the same composition. In another example, at least a portion of the spatially separated electrode surfaces have different compositions. In Figure 6C , Fig.6D In , WE1 represents a first working electrode surface configured to operate, for example, under P1 and electrically isolated from a second working electrode surface WE2 configured to operate under P2, and RE represents a reference electrode RE electrically isolated from both WE1 and WE2. Figure 6C In the configuration of , a resistive domain is provided, which covers the reference electrode and WE1, WE2. Fig.6DAn additional resistance domain is provided in the configuration, which substantially only covers WE2 and extends thereon. Additional electrodes, such as counter electrodes, may be used. Such configurations (whether single-wire or dual-wire configurations) may also be used to measure the same analyte using two different techniques. Using different signal generation sequences and different RLs, data collected from measurements of two different modes provide increased fidelity, improved performance, and device life. Non-limiting examples are glucose oxidase (producing H2O2) and glucose dehydrogenase (electrical coupling) configurations. Measuring glucose from two different electrodes at two potentials provides more data points and accuracy. Such methods may not be necessary for glucose sensing, but may be applied to biomarker sensing spectra of other analytes, such as ketone sensing, ketone / lactate sensing, and ketone / glucose sensing, either alone or in combination with glucose sensing.

[0368] exist Figure 6C , Fig.6D In the depicted alternative configuration, two or more wire electrodes that can be co-linear, wound or otherwise juxtaposed are presented, wherein WE1 is separated from WE2, for example, from other elongated electrodes. An insulating layer electrically isolates WE1 from WE2. In this configuration, independent electrode potentials can be applied to corresponding electrode surfaces, wherein independent electrode potentials can be provided to WE1, WE2 simultaneously, sequentially or randomly. In one example, the electrode potentials presented to corresponding electrode surfaces WES1, WES2 are different. One or more additional electrodes may be present, such as reference electrodes and / or counter electrodes. In one example, WES2 is positioned at the longitudinal distal side of WES1 in an elongated arrangement. Using, for example, a dip coating method, WES1 and WES2 are coated with enzyme domain EZL1, and WES2 is coated with different enzyme domains EZL2. Based on dipping parameters or enzyme domains of different thicknesses, multilayer enzyme domains can be used, each layer independently including enzymes and / or cofactors, mediators of different loads and / or compositions. Likewise, one or more resistive domains (RL) may be applied, each of which may have a different thickness along the longitudinal axis of the electrode and on different electrode and enzyme domains, for example by controlling the dipping length and other parameters. Fig.6D , depicts such an arrangement of RL's, where an additional RL 152' is adjacent to WES2, but not substantially within WES1.

[0369] In one example of measuring two different analytes, the above configuration includes an enzyme domain EZL1 155, which includes one or more enzymes and one or more mediators for at least one enzyme of EZL1 to provide direct electron transfer to WES1 and determine the concentration of at least a first analyte. In addition, the enzyme domain EZL2 156 may include at least one enzyme that provides peroxide (e.g., hydrogen peroxide) or consumes oxygen during catalysis with its substrate. The peroxide or oxygen generated in EZL2 156 migrates to WES2 and provides a detectable signal corresponding directly or indirectly to the second analyte. For example, WES2 can be carbon, connected to glucose dehydrogenase to measure glucose, and WES1 can be platinum, which measures peroxide produced by lactate oxidase / lactate in EZL2 156. The combinations of electrode materials and enzymes disclosed herein are exemplary and non-limiting.

[0370] In one example, the potentials of P1 and P2 may be separated by a certain amount of potential so that two signals (from direct electron transfer from EZL1155 and from hydrogen peroxide oxidation reduction at WE) can be activated and measured separately. In one example, the electronic module of the sensor can be continuously switched between two sensing potentials in a continuous or semi-continuous periodic manner, such as a period (t1) at potential P1 and a period (t2) at potential P2, optionally with a rest time without applying a potential. The extracted signal can then be analyzed to measure the concentrations of two different analytes. In another example, the electronic module of the sensor may undergo cyclic voltammetry, and the current changes provided when sweeping the potentials of P1 and P2 may be related to the transduction signals from direct electron transfer or hydrogen peroxide electrolysis, respectively. In one example, the mode of sensing is non-limiting and may include different amperometric techniques, such as cyclic voltammetry. In one example, an alternative configuration is provided, but the hydrogen peroxide production in EZL2 is replaced by another suitable electrolytic compound (such as oxygen) that maintains the P2≠P1 relationship and at least one enzyme-substrate combination that provides another electrolytic compound.

[0371] For example, a continuous multi-analyte sensor configuration for choline and glucose was prepared, in which the enzyme domains EZ1 155, EZ2 156 were associated with different WEs (e.g., platinum WE2 and gold WE1). In this exemplary case, EZL1 155 contains glucose oxidase and a mediator coupled to WE1 to facilitate direct electron transfer when glucose is catalyzed, and EZL2 156 contains choline oxidase, which will catalyze choline and generate hydrogen peroxide for electrolysis at WE2. EZL' is coated with a resistive domain; after curing and preparation, they undergo cyclic voltammetry in the presence of glucose and choline. Glucose oxidase wired to a gold electrode is able to transduce a signal at 0.2 volts, so by analyzing the current change at 0.2 volts, the glucose concentration can be determined. The data also shows that if the CV trace is analyzed at voltage P2, the choline concentration can also be inferred to be detected at the WE2 platinum electrode.

[0372] In one example, the electrode WE1 or WE2 can be, for example, a composite material, such as a gold electrode with a platinum ink deposited on top, a carbon / platinum mixture, and / or trace carbon on top of the platinum, or a porous carbon coating on the platinum surface. In one example, the electrode surface contains two different materials, for example, carbon for ligation and electron transfer, and platinum for hydrogen peroxide oxidation reduction and detection. Fig. 6E , an example of such a composite electrode surface is shown, wherein an extended platinum-covered wire 157 is half-coated with carbon 158 to facilitate multi-sensing on two different surfaces of the same electrode. In one example, WE2 can be grown on or extend from a portion of the surface or distal end of WE1, such as by vapor deposition, sputtering, or electrolytic deposition.

[0373] Additional examples include composite electrode materials that can be used to form one or both of WE1 and WE2. In one example, a platinum-carbon electrode WE1 including EZL1 with glucose dehydrogenase is wired to a carbon surface, and the outer EZL2 includes lactate oxidase that generates hydrogen peroxide, which can be detected by the platinum surface of the same WE1 electrode. Other examples of this configuration may include ketone sensing (β-hydroxybutyrate dehydrogenase galvanocoupler in EZL1 155) and glucose sensing (glucose oxidase in EZL2 156). Other membranes can be used in the aforementioned configurations, such as electrodes, resistors, biointerfaces, and drug release membranes. In other examples, one or both of the working electrodes (WE1, WE2) can be gold-carbon (Au-C), palladium-carbon (Pd-C), iridium-carbon (Ir-C), rhodium-carbon (Rh-C), or ruthenium-carbon (Ru-C). In some examples, the carbon in the working electrodes discussed herein may alternatively or additionally include graphene, graphene oxide, or other materials suitable for forming a working electrode, such as commercially available carbon inks.

[0374] Fig. 6F Graphically depicts the Figure 6B Scan traces obtained with the configuration depicted in , where the current at 0.7 volts is plotted at each sweep of the CV. Glucose was spiked from 50 mg / dl to 200 mg / dl, followed by choline spikes from 0.5 mg / dl to 14.5 mg / dl. At 0.7 V, the data indicate that the platinum WE2 electrode (n=4) is sensitive to both glucose and choline, while the trace from the gold WE1 electrode (n=4) only shows a change in current at 0.7 V when choline is spiked. This change may be due to the formation of hydrogen peroxide in the non-electrically coupled outer EZL2 layer 156 and partial detection of hydrogen peroxide at the gold electrode. Nevertheless, in combination with detecting glucose at P1 (0.2 volts) on the gold WE1 electrode, a continuous multi-analyte sensor can be used to detect both glucose and choline.

[0375] In one example, the first layer EZL1 155 includes an oxidase that does not produce hydrogen peroxide. These enzymes include, but are not limited to, lactate dehydrogenase, glucose dehydrogenase, β-hydroxybutyrate dehydrogenase, diaphorase, etc. In one example, these dehydrogenases are wired to at least a portion of the WE1 electrode to reduce or eliminate crosstalk, reduce potential, and minimize or eliminate interfering signals. In one example, EZL1 155 may include any enzyme that can provide electron transfer when wired or covalently coupled to the electrode surface or in the presence of any type of redox mediator, and EZL2 156 may include any oxidoreductase that produces hydrogen peroxide or other suitable compounds that will be oxidized, reduced, or electrolyzed at the electrode surface under the applied potential.

[0376] In one example, the aforementioned continuous choline sensor configuration can be combined with any of the aforementioned continuous alcohol sensor configuration, continuous uric acid sensor configuration, continuous cholesterol sensor configuration, continuous bilirubin / ascorbic acid sensor configuration, continuous ketone, ketone and glucose, or ketone and lactate, and other sensor configurations to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capabilities.

[0377] Glycerol sensor configuration

[0378] like Fig. 7A , depicts an exemplary continuous glycerol sensor configuration, wherein a first enzyme domain EZL1 160 including galactose oxidase is positioned close to at least a portion of the WE surface. A second enzyme domain EZL2 161 including glucose oxidase and catalase is positioned further away from the WE. Fig. 7AAs shown, one or more resistance domains (RL) 152 are positioned between EZL1 160 and EZL2 161. Additional RLs may be employed, such as adjacent to EZL2 161. It is contemplated that modifications to one or more RL membranes may be made to attenuate the flux of either analyte and increase the ratio of glycerol to galactose sensitivity. The above-described glycerol sensing configuration provides a glycerol sensor that may be combined with one or more additional sensor configurations as disclosed herein.

[0379] Glycerol can be catalyzed by galactose oxidase (GalOx), however, GalOx has an activity ratio of 1% to 5% on glycerol. In one example, the activity of GalOx on this secondary analyte glycerol can be utilized. The relative concentration of glycerol in the body is much higher than that of galactose (galactose is about 2umol / l, while glycerol is about 100umol / l), which supplements the aforementioned configuration.

[0380] If the GalOx present in the EZL1 160 membrane is not otherwise functionally constrained, the GalOx will catalyze most, if not all, of the glycerol passing through one or more RLs. The signal contribution from the glycerol present will be higher than that from galactose. In one example, one or more RL's are chemically configured to provide a higher influx of glycerol or a lower influx of galactose.

[0381] In another example, a diol sensor configuration is provided using multiple working electrodes WE, which utilizes signals transduced from two WEs. Utilizing signals transduced from two WEs can provide increased selectivity. In one example, EZL1 160 and EZL2 161 include the same oxidase (e.g., galactose oxidase) with different enzyme loading ratios, and / or different immobilized polymers and / or different numbers and layers of RL' on WE. Such configurations provide measurements of the same target analyte with different sensitivities, thereby achieving dual measurements. A mathematical algorithm is used to correct noise and interference from the first signal, and a first signal of a sensing electrode with a first analyte sensitivity ratio is input into the mathematical algorithm, allowing decoupling of a second signal corresponding to the desired analyte contribution. The sensitivity ratio of one or more EZLs can be modified by adjusting one or more of the enzyme source, enzyme loading in the EZL, chemical properties / diffusion characteristics of the EZL, chemical / diffusion characteristics of at least one RL, and combinations thereof to distinguish signals from interfering substances and analytes of interest.

[0382] As discussed herein, secondary enzyme domains can be used to catalyze non-target analytes, reduce their concentration and limit diffusion through adjacent membranes containing primary enzymes and necessary additives toward the sensing electrode. In this example, the most distal enzyme domain EZL2 161 is configured to catalyze non-target analytes (which would otherwise react with EZL1), thereby providing a potentially less accurate reading of the concentration of the target analyte (glycerol). The secondary enzyme domain itself can act as a "selective diffusion exclusion membrane", or in some other configurations can be placed above or below the resistive layer (RL) 152. In this example, the target analyte is glycerol, and GalOX is used to catalyze glycerol to form a measurable substance (e.g., hydrogen peroxide).

[0383] Figure 7B The sensitivity variation of glycerol sensors is shown, where galactose oxidase is used as the main enzyme for converting glycerol and in some cases a secondary "selective diffusion exclusion membrane" with or without an additional RL layer is used. Figure 7B As shown, the application of a selective secondary enzyme domain can increase the selectivity of the sensing platform for target analytes. For example, as shown, the sensitivity ratio (sensitivity to targeted analytes / sensitivity to non-targeted analytes) can be increased by utilizing a RL selective secondary enzyme domain. Figure 7B Four impregnation configurations are shown, including: no enzyme or RL (labeled "No RL"), in which there is neither a secondary enzyme selective layer nor an RL; no RL, which includes a secondary enzyme domain (labeled "No RL+GOXCAT"), in a configuration including a secondary enzyme domain that catalyzes non-targeted analytes; no enzyme RL (labeled "RL"), this configuration contains only a resistance domain; and a final configuration that includes an RL layer, which is placed below the selective secondary enzyme domain (and can be described as being located between two EZLs (labeled "RL+GOX-CAT")). Figure 7B “No RL” and “RL” in indicate examples including and excluding a resistance domain, respectively. Figure 7B The "no RL+GOXCAT" and "RL+GOXCAT" in the figure indicate example sensors configured to have an outer layer containing GOX and catalase without and with RL, respectively. Compared to the "no RL+GOXCAT" configuration that does not include RL, for the RL+GOXCAT configuration, an increase in the glycerol / galactose sensitivity ratio with a smaller change relative to the RL-impregnated configuration is shown.

[0384] In one example, a continuous glycerol sensor configuration is provided using at least a glycerol oxidase, which provides hydrogen peroxide when reacting and catalyzing glycerol. Thus, in one example, an enzyme domain comprising a glycerol oxidase may be positioned adjacent to at least a portion of a WE surface, and hydrogen peroxide is detected using amperometry. In another example, an enzyme domain comprising a glycerol oxidase is used to sense changes in oxygen levels, such as in a Clark-type electrode setup. Alternatively, at least a portion of the WE surface may be coated with one or more layers of an electrically coupled polymer, such as the mediator system discussed below, to provide a coated WE capable of transferring electrons from the enzyme at a lower potential. The coated WE may then be operated at a different and lower voltage to measure oxygen and its correlation with glycerol concentration.

[0385] In another example, glycerol-3-phosphate oxidase is used in the enzyme domain to provide a glycerol sensor configuration. In one example, ATP is used as a cofactor. Thus, Figure 7C and Fig.7D , depicting an exemplary sensor configuration, wherein in one example ( Figure 7C ), one or more cofactors (e.g., ATP) 162 are close to at least a portion of the WE surface. An enzyme domain comprising one or more enzyme domains 163 is adjacent to the cofactor, or is further away from the WE surface than the cofactor layer 162, and the one or more enzyme domains include glycerol-3-phosphate oxidase (3PD), lipase and / or glycerol kinase (GK) and one or more regeneration enzymes capable of continuously regenerating the cofactor. Examples of regeneration enzymes that can be used to provide ATP regeneration include, but are not limited to, ATP synthase, pyruvate kinase, acetate kinase, and creatine kinase. One or more regeneration enzymes may be included in one or more enzyme domains, or in a separate layer.

[0386] exist Fig.7D An alternative configuration is shown in , wherein one or more enzyme domains 163 including G3PD, at least one cofactor, and at least one regeneration enzyme are positioned proximal to at least a portion of the WE surface, wherein one or more cofactor reservoirs 162 are positioned proximal to the enzyme domain including G3PD and further from the WE surface, and one or more RL' 152 are positioned proximal to the cofactor reservoir. In any of these configurations, an additional enzyme domain (which includes a lipase) may be included to indirectly measure triglycerides, as the lipase will produce glycerol for detection by the aforementioned glycerol sensor configuration.

[0387] Fig. 7E Graphically depicts the use of Fig.7DThe current response to the stepwise addition of glycerol levels measured using amperometry at 0.6 volts and a low physiological concentration range for the glycerol kinase, glycerol 3-phosphate oxidase, and ATP sensor configuration described in . The "low" range in this example can be based on expected glycerol values ​​of about 5uM to about 100uM, so the low value can be a value below about 50uM. In other examples, the low glycerol value can be a value below about 25uM. In other examples, the low glycerol value can be below about 10uM. In yet another example, the low glycerol value can be below about 5uM.

[0388] In another example, a dehydrogenase is used with a cofactor and a regenerating enzyme to provide a glycerol sensor configuration. In one example, the cofactor that can be bound to one or more enzyme domains includes one or more of NAD(P)H, NADP+, and ATP. In one example, for example, for the use of NAD(P)H, the regenerating enzyme can be NADH oxidase or diaphorase to convert NADH (a product catalyzed by the dehydrogenase) back to NAD(P)H. Similar methods can be used to generate other glycerol sensors, for example, glycerol dehydrogenase, in combination with NADH oxidase or diaphorase, can be configured to measure glycerol or oxygen.

[0389] In one example, mathematical modeling can be used to identify and remove interfering signals, measure very low analyte concentrations, signal error and noise reduction to improve and increase the service life of multi-analyte sensors. For example, for a dual WE electrode configuration, where WE1 is coated with a first EZL and WE2 is coated with two or more different EZLs, optionally with one or more resistance domains (RL), such interference can be mathematically corrected to provide increased accuracy of measurement.

[0390] Variations in enzyme loading, immobilized polymer, and resistive domain characteristics on each analyte sensing region can result in different sensitivity ratios between two or more target analytes and interfering substances. If mathematical modeling is used to collect and analyze the signals, a more precise concentration of the target analyte can be calculated.

[0391] One example where the use of mathematical modeling may be helpful is glycerol sensing, where galactose oxidase is sensitive to both galactose and glycerol. The sensitivity ratio of galactose oxidase to glycerol is approximately 1% to 5% of its sensitivity to galactose. In such cases, the sensitivity ratio to the two analytes can be modified by adjusting one or more parameters, such as enzyme source, enzyme loading, enzyme zone (EZL) diffusion characteristics, RL diffusion characteristics, and combinations thereof. If two WEs are operated in a sensor system, the use of mathematical modeling to calibrate and analyze the signals from the two WEs provides a high degree of fidelity and target analyte concentration measurement.

[0392] In the above configurations, the proximity of one or more of the enzyme immobilization layers discussed herein to the WE may be different or opposite, such as may be used if the enzyme immobilization layer closest to the WE enzyme domain provides hydrogen peroxide.

[0393] In some examples, one or more enzymes working in concert may be used to measure the target analyte. In one example, ATP may be immobilized in one or more EZL membranes, or may be added to an adjacent layer alone or in combination with a second cofactor, or may be regenerated / recycled for use in the same EZL or an adjacent third EZL. The configuration may also include a cofactor regenerating enzyme, such as an alcohol dehydrogenase or NADH oxidase, to regenerate NAD(P)H. Other examples of cofactor regenerating enzymes that can be used to regenerate ATP are ATP synthase, pyruvate kinase, acetate kinase, creatine kinase, and the like.

[0394] In one example, the aforementioned continuous glycerol sensor configuration can be combined with any of the aforementioned continuous alcohol sensor configuration, continuous uric acid sensor configuration, continuous cholesterol sensor configuration, continuous bilirubin / ascorbic acid sensor configuration, ketone sensor configuration, choline sensor configuration to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capabilities. Other configurations may be used in the aforementioned continuous glycerol sensor configuration, such as electrodes, resistors, biointerfaces, and drug release membranes.

[0395] Creatinine sensor configuration

[0396] In one example, a continuous creatinine sensor configuration is provided, such configuration contains one or more enzymes and / or cofactors. The creatinine sensor configuration is an example of a continuous analyte sensing system that generates intermediates, interfering products, where these intermediates / interfering substances are also present in the sampled biological fluid. The present disclosure provides solutions to these technical problems and provides accurate, stable and continuous creatinine monitoring alone or in combination with other continuous multi-analyte sensor configurations.

[0397] Creatinine sensors undergo changes in many physiologically present intermediates / interference products (e.g., sarcosine and creatine) during use, which can affect the correlation of the transduction signal with the creatinine concentration. For example, the physiological concentration range of sarcosine is one order of magnitude lower than that of creatinine or creatine, so the signal contribution from circulating sarcosine is generally minimal. However, changes in local physiological creatine concentrations can affect the creatinine sensor signal. In one example, such signal contributions are eliminated or reduced.

[0398] Therefore, in one example, eliminating or reducing the creatine signal contribution of the creatinine sensor includes using at least one enzyme that will consume non-target interfering analytes (creatine in this case). For example, two enzyme domains located adjacent to each other are used. At least a portion of the first enzyme domain is located close to at least a portion of the WE surface, and the first enzyme domain includes one or more enzymes selected from creatinine amide hydrolase (CNH), creatine amide hydrolase (CRH) and sarcosine oxidase (SOX). The second enzyme domain adjacent to the first enzyme domain and further away from the WE surface includes one or more enzymes, and the one or more enzymes use creatine as their substrate to eliminate or reduce the diffusion of creatine toward WE. In one example, the combination of enzymes includes CRH, SOX, creatine kinase and catalase, wherein the enzyme ratio is adjusted to provide a sufficient number of units so that circulating creatine will be at least partially consumed by CRH, thereby providing sarcosine and urea, and the sarcosine produced will be at least partially consumed by SOX, thereby providing an oxidized form of glycine (e.g., glycine aldehyde), which will be at least partially consumed by catalase. In the above-mentioned alternative configuration, urea produced by CRH catalysis can be at least partially consumed by urease to provide ammonia, wherein the aqueous form (NH4+) is detected via an ion selective electrode (e.g., non-actin ion carrier). Such alternative potentiometric sensing configurations can provide alternatives to current-measured peroxide detection (e.g., improved sensitivity, detection limits, and non-loss of reference electrodes, alternative paths / mechanisms). This dual analyte sensing example may include a creatinine-potassium sensor having potentiometric sensing at two different working electrodes. In this example, interference signals can be identified and corrected. In an alternative example, the aforementioned configuration may include a multi-mode sensing architecture, which uses a combination of amperometry and potentiometric methods to detect the concentrations of peroxide and ammonium ions, and the concentrations of peroxide and ammonium ions are measured using amperometry and potentiometric methods, respectively, and are associated with measuring creatinine concentrations. In one example, the aforementioned configuration may also include separating two enzyme domains to provide one or more configurations (e.g., enzyme-free) of complementary or assisted diffusion separation and barriers.

[0399] In yet another example, a method of separating the signal and measuring substantially only creatinine is to use a second WE that measures an interfering substance (e.g., creatine) and then use mathematical modeling to correct the signal. Thus, for example, the signal from the WE that interacts with creatine is used as a reference signal. The signal from another WE that interacts with creatinine is corrected based on the signal from the WE that interacts with creatine to selectively determine the creatinine concentration.

[0400] In yet another example, sensing creatinine is by electrochemically measuring changes in oxygen levels, such as in a Clark-type electrode setup, or using electrodes coated with different polymers such as NAFION TM) layer and correlate potential changes based on oxygen changes, which will be indirectly related to creatinine concentration.

[0401] In yet another example, sensing creatinine is by using sarcosine oxidase wired to at least one WE using one or more electrically coupled mediators. In this method, creatinine concentration will be indirectly related to the signal generated by electron transfer collected from the WE.

[0402] For the aforementioned creatinine sensor configurations based on hydrogen peroxide and / or oxygen measurement, one or more enzymes may be in a single enzyme domain, or one or more enzymes may be independently in one or more enzyme domains, or any other combination thereof, wherein at least one enzyme is present in each layer. For the aforementioned creatinine sensor configurations based on a sarcosine oxidase-containing layer using electrical coupling, the layer is positioned adjacent to an electrode and is electrically coupled to at least a portion of the electrode surface using a mediator.

[0403] In another example, the aforementioned creatinine sensor configuration can be sensed using potentiometric methods using urease (UR), which produces ammonium from urea, which is produced by CRH from creatine, which is formed by the interaction of creatinine with CNH. Therefore, ammonium can be measured by the above configuration and correlated with creatinine concentration. Alternatively, creatinine amide hydrolase (CI) or creatinine deiminase can be used to generate ammonia gas, which will provide ammonium ions for signal transduction under physiological conditions of a transcutaneous sensor.

[0404] In yet another example, sensing creatinine is by using one or more enzymes and one or more cofactors. Some non-limiting examples of such configurations include creatinine deaminase (CD) that provides ammonium from creatinine, glutamate dehydrogenase (GLDH) that provides peroxide from ammonium, wherein the hydrogen peroxide is related to the current level of creatinine. The above configuration may also include a third enzyme: glutamate oxidase (GLOD) to further decompose the glutamate formed by GDLH and produce additional hydrogen peroxide. Such combinations of enzymes may be independently in one or more enzyme domains or any other combination thereof, wherein at least one enzyme is present in each domain or layer.

[0405] In yet another example, sensing creatinine is by a combination of creatinine amide hydrolase (CNH), creatine kinase (CK), and pyruvate kinase (PK), wherein pyruvate produced by PK can be detected by one or more of independently configured lactate dehydrogenase (LDH) or pyruvate oxidase (POX), wherein one or more of the foregoing enzymes are present in one layer, or wherein each of the multiple layers includes at least one enzyme; any other combination thereof.

[0406] In such sensor configurations using one or more cofactors and / or regenerative enzymes for the cofactors, one or more of NADH, NAD(P)H, and ATP may be provided in excess in any of the one or more configurations, and one or more diffusion resistance domains may be introduced to limit or prevent the efflux of the cofactors from their respective membranes. Other configurations may be used in the aforementioned configurations, such as electrodes, resistors, biointerfaces, and drug release membranes.

[0407] In yet another example, creatinine detection is provided by using creatinine deiminase in one or more enzyme domains and providing ammonium to the enzyme domains via catalysis of creatinine. The detection can then be performed potentiometrically or by using a composite electrode (e.g., NAFION) that undergoes redox when exposed to ammonium ions. TM / polyaniline composite electrode) to detect ammonium ions, where the polyaniline undergoes redox in the presence of ammonium at the electrode under potential. The ammonium concentration can then be correlated to the creatinine concentration.

[0408] Fig. 8A An exemplary continuous sensor configuration for creatinine is depicted. Fig. 8A In an example, the sensor includes a first enzyme domain 164, which includes CNH, CRH and SOX adjacent to the working electrode WE (e.g., platinum). The second enzyme domain 165 is located adjacent to the first enzyme domain and is further away from the WE. One or more resistance domains (RL) 152 can be located adjacent to the second enzyme domain or between the first layer and the second layer. Creatinine can diffuse to the first enzyme domain through the RL and the second enzyme domain, where it is converted into peroxide and transduces a signal corresponding to its concentration. Creatine can diffuse through the RL and be converted into sarcosine and urea in the second enzyme domain, sarcosine is consumed by sarcosine oxidase, and the generated peroxide is consumed by catalase, thereby preventing the transduction of creatine signals.

[0409] Figure 8B Depicted are experimental results for an exemplary creatinine sensor with the above (CNH, CRH, SOX) configuration using a platinum electrode surface. The data demonstrate reproducible sensitivity within the physiological range of creatinine with drift stability up to 7 days ( Figure 8C ). Such combinations of CNH enzymes, CRH enzymes, SOX enzymes may be independently in one or more enzyme domains or any other combination thereof, wherein at least one enzyme is present in each layer. In addition, such sensor configurations may include one or more electrode domains, interference membranes, resistance domains, in order to modify and adapt the sensitivity, selectivity and stability of the sensor.

[0410] For example, for continuous monitoring of creatinine alone or in combination with one or more other analytes, variations of the above configurations are possible. Thus, an alternative method of sensing creatinine may be electrochemical sensing of changes in oxygen levels, such as in a Clark-type electrode setup. In one example, the WE may be coated with different polymers (such as NAFION TM ) layer, and based on the change in possible oxygen changes, the creatinine concentration can be relevant. In another example, one or more mediators can be used to "wire" one or more enzymes (i.e., sarcosine oxidase) closest to the WE to the electrode. Each of the different enzymes in the above configuration can be distributed within a polymer matrix or domain to provide an enzyme domain. In another example, one or more of the different enzymes discussed herein can be formed as an enzyme domain and can be formed layer by layer, with at least one enzyme present in each layer. In the example of a "wired" enzyme configuration with a multilayer membrane, the wired enzyme domain will be closest to the electrode. One or more interferent layers can be deposited in the multilayer enzyme configuration to prevent non-target analytes from reaching the electrode.

[0411] In one example, the aforementioned continuous creatinine sensor configuration can be combined with any of the aforementioned continuous alcohol sensor configuration, continuous uric acid sensor configuration, continuous cholesterol sensor configuration, continuous bilirubin / ascorbic acid sensor configuration, ketone sensor configuration, choline sensor configuration, glycerol sensor configuration to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capability.

[0412] Lactose sensor configuration

[0413] In one example, a continuous lactose sensor configuration is provided, which is combined with another analyte sensing configuration including one or more enzymes and / or cofactors. In a general sense, a lactose sensing configuration using at least one enzyme domain including lactase is used to produce glucose and galactose from lactose. The glucose or galactose produced is then enzymatically converted into peroxide for signal transduction at the electrode. Therefore, in one example, at least one enzyme domain EZL1 including lactase is positioned close to at least a portion of the WE surface capable of electrolyzing hydrogen peroxide. In one example, glucose oxidase (GOX) is included in EZL1, with one or more cofactors or electrically coupled mediators. In another example, galactose oxidase (GalOx) is included in EZL1, optionally with one or more cofactors or mediators. In one example, glucose oxidase and galactose oxidase are both included in EZL 1. In one example, glucose oxidase and galactose oxidase are both included in EZL 1, optionally with one or more cofactors or electrically coupled mediators.

[0414] One or more additional EZL' (e.g., EZL2) may be positioned adjacent to EZL1, wherein at least a portion of EZL2 is further away from at least a portion of WE than EZL1. In one example, one or more layers may be positioned between EZL1 and EZL2, such layers may include an enzyme, a cofactor, or a mediator, or may be substantially free of one or more of an enzyme, a cofactor, or a mediator. In one example, one or more layers positioned between EZL1 and EZL2 are substantially free of enzymes, such as free of intentionally added enzymes. In one example, one or more layers may be positioned adjacent to EZL2, further away from at least a portion of EZL1 than EZL2, and include one or more of the enzymes present in EZL1 or EZL2.

[0415] In one example of the aforementioned lactose sensor configuration, a peroxide-generating enzyme can be electrically coupled to an electrode using a coupling mediator.The transduced peroxide signal from the aforementioned lactose sensor configuration can be correlated to the level of lactose present.

[0416] Fig.9A , Fig. 9B , Fig. 9C and Fig.9D An alternative continuous lactose sensor configuration is depicted. Thus, in the enzyme domain EZL1 164 that includes GalOx and lactase closest to WE (G1), a lactose sensor is provided that is sensitive to changes in galactose and lactose concentrations and does not substantially transduce glucose concentration. Fig. 9B , Fig. 9C and Fig.9D As shown, additional layers are used, including an enzyme-free layer 159 and a lactase-containing layer 165, as well as optional electrodes, resistors, biointerfaces, and drug release membranes (not shown). Since changes in physiological galactose concentrations are small, the transduction signal is essentially derived from physiological lactose fluctuations. Fig.9E Indicates that from Fig. 9C Linear response to lactose for the above configuration depicted in FIG.

[0417] In one example, the aforementioned continuous lactose sensor configuration can be combined with any of the aforementioned continuous alcohol sensor configuration, continuous uric acid sensor configuration, continuous cholesterol sensor configuration, continuous bilirubin / ascorbic acid sensor configuration, ketone sensor configuration, choline sensor configuration, glycerol sensor configuration, creatinine sensor configuration to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capabilities. Other membranes can be used in the aforementioned sensor configurations, such as electrodes, resistors, biointerfaces, and drug release membranes.

[0418] Urea sensor configuration

[0419] Similar methods as described above can also be used to create continuous urea sensors. For example, urease (UR), which can decompose urea and provide ammonium, can be used in an enzyme domain configuration. Ammonium can be detected potentiometrically or by using a composite electrode (e.g., an electrode that undergoes redox when exposed to ammonium). Example electrodes for ammonium signal transduction include, but are not limited to, NAFION TM The invention relates to a polyaniline / polyaniline composite electrode, wherein the polyaniline undergoes redox in the presence of ammonium under an applied potential, wherein the signal is substantially directly related to the level of ammonium present in the surrounding. The method can also be used to measure other analytes such as glutamate using glutaminase (GLUS).

[0420] In one example, the aforementioned continuous uric acid sensor configuration can be combined with any one of the aforementioned continuous alcohol sensor configuration and / or continuous uric acid sensor configuration and / or continuous cholesterol sensor configuration and / or continuous bilirubin / ascorbic acid sensor configuration and / or continuous ketone sensor configuration and / or continuous choline sensor configuration and / or continuous glycerol sensor configuration and / or continuous creatinine sensor configuration and / or continuous lactose sensor configuration to provide a continuous multi-analyte sensor device as further described below. The continuous multi-analyte sensor device may also include continuous glucose monitoring capabilities. Other membranes may be used in the aforementioned uric acid sensor configuration, such as electrodes, resistors, biointerfaces, and drug release membranes.

[0421] mediator

[0422] One or more mediators can be used to facilitate electrolysis of one or more analytes or electrolysis of a second compound that is associated with or interferes with signal transduction of one or more analytes. Non-polymeric and polymeric redox mediators can be used in the continuous multi-analyte sensor devices disclosed herein.

[0423] In one example, zwitterionic compounds / compounds, Prussian blue, medola blue, methylene blue, methylene green, methyl viologen, ferrocyanide, ferrocene, cobalt ions, and cobalt phthalocyanine can be used as coatings on one or more WEs to promote or otherwise assist in the transfer and transduction of electrons corresponding to detectable signals of one or more analytes. In one example, a transition metal complex is attached to one or more polymer backbones as a redox mediator. In one example, the transition metal complex includes at least one substituted or unsubstituted biimidazole ligand. In another example, the transition metal complex includes at least one substituted or unsubstituted biimidazole ligand and a substituted or unsubstituted bipyridine or pyridyl imidazole ligand.

[0424] In one example, the mediator is one or more metal compounds or metal complexes of ruthenium, osmium, iron (e.g., polyvinylferrocene or hexacyanoferric acid), or cobalt, including, for example, their metallocene compounds. In one example, the mediator is coupled or otherwise bound to a conductive material of any one of a reference electrode, a working electrode, or a counter electrode. In one example, a non-polymeric or polymeric mediator may be adsorbed on or covalently bound to a conductive material of an electrode, such as a carbon surface or a surface of gold, platinum, palladium, rhodium, and alloys thereof. In one example, the mediator is quaternized.

[0425] A variety of methods can be used to immobilize polymeric or non-polymeric mediators on the electrode surface, for example, adsorption with or without crosslinking, vapor deposition, functionalization of at least a portion of the electrode surface, followed by chemical bonding (ionically or covalently) of the mediator polymer to the functional groups on the electrode surface. In one example, poly(4-vinylpyridine) or polyvinylpyridine-co-styrene or polyvinylimidazole is at least partially complexed with a transition metal compound, such as [Os(bpy)2Cl] + / 2+ , wherein bpy is 2,2′-bipyridine. In one example, at least a portion of the pyridine rings of poly(4-vinylpyridine) or polyvinylpyridine-co-styrene are reacted with 2-bromoethylamine and then crosslinked, for example, using a diepoxide such as polyethylene glycol diglycidyl ether. Other polymers and / or non-polymer mediators such as PVI-ruthenium and PVP-ruthenium (phenanthrolinedione) may be used.

[0426] The carbon surface can be modified to attach one or more polymeric and / or non-polymeric mediators, for example, by electrolytic reduction of a diazonium salt, followed by activation by a carbodiimide such as 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride, and then combined with an amine-functionalized mediator such as the above-mentioned osmium-containing polymer or 2-aminoethylferrocene to form a mediator couple.

[0427] Similarly, gold can be functionalized with thiols or amines, such as cystamine, and the mediator [Os(bpy)2(pyridine-4-carboxylate)Cl]0 / + can be activated by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride to form reactive O-acylisoureas that react with gold-bound amines to form amides.

[0428] Modified enzyme

[0429] In other examples, a genetic variant of any of the aforementioned enzymes is used, for example, a variant that improves heat resistance (e.g., storage or shelf stability and / or operational stability). Examples of genetic mutations that improve enzyme thermal stability include, but are not limited to, adding stabilizers (such as substrates and similar ligands, sugars, polymers, specific and nonspecific ionic substances, and small uncharged organic molecules), immobilization, protein engineering (e.g., site-directed mutagenesis), and / or chemical modification. In one example, an enzyme isolated from anaerobic extreme thermophiles, such as NADH oxidase isolated from Clostridium thermohydrosulfuricum, Thermus thermophilus, Thermoanaerobium brockii, Streptococcus mutans, Pyrococcus horikoshii, and Bacillus licheniformis, is used to confer at least some thermal operational stability to the sensor, for example, up to about 80°C.

[0430] Additional single and multi-electrode configurations

[0431] The aforementioned multi-analyte sensor configurations may be adapted for use with continuous multi-analyte sensor electrode configurations. For example, FIG. 10A to FIG. 10C One aspect of a continuous multi-analyte sensor 100 (eg, an in vivo portion) is illustrated, which includes an elongated conductive body 102. The elongated conductive body 102 includes a core 110 (see Fig. 10B ) and a first conductive layer 112 at least partially surrounding the core. The first layer includes a working electrode (e.g., located in window 106) and a membrane 108 located above the working electrode, the membrane being configured and arranged for multi-axis bending. In some examples, the core and the first layer may have a single material (e.g., platinum). In some examples, the elongated conductor is a composite of at least two materials, such as a composite of two conductive materials, or a composite of at least one conductive material and at least one non-conductive material. In some examples, the elongated conductor includes multiple layers. In some examples, there are at least two concentric (e.g., annular) layers, such as a core formed of a first material and a first layer formed of a second material. However, in some examples, additional layers may be included. In some examples, the layers are coaxial.

[0432] The elongated conductor can be long and thin, yet flexible and strong. For example, in some examples, the smallest dimension of the elongated conductor is less than about 0.1 inches, 0.75 inches, 0.05 inches, 0.25 inches, 0.01 inches, 0.004 inches, or 0.002 inches. FIG. 10A to FIG. 10CIn the example, the elongated conductor is illustrated as having a circular cross-section, but in other examples, the cross-section of the elongated conductor can be oval, rectangular, triangular, polyhedral, star-shaped, C-shaped, T-shaped, X-shaped, Y-shaped, irregular, etc. In one example, a conductive wire electrode is used as the core. For such a coated electrode, two additional conductive layers can be added (e.g., with an intermediate insulating layer provided for electrical isolation). These conductive layers can be made of any suitable material. In some examples, it may be desirable to use a conductive layer containing conductive particles (i.e., particles of conductive material) in a polymer or other binder.

[0433] In one example, the material used to form the elongated conductor (e.g., stainless steel, titanium, tantalum, platinum, platinum-iridium, iridium, certain polymers, etc.) can be strong and hard, and therefore resistant to breakage. For example, in some examples, the ultimate tensile strength of the elongated conductor is about 80 kPsi to about 500 kPsi. In another example, in some examples, the Young's modulus of the elongated conductor is about 160 GPa to about 220 GPa. In yet another example, in some examples, the yield strength of the elongated conductor is about 60 kPsi to about 2200 MPa. Ultimate tensile strength, Young's modulus, and yield strength are discussed in more detail elsewhere herein. In some examples, the small diameter of the sensor provides (e.g., imparts, enables) flexibility to these materials, and therefore provides flexibility to the entire sensor.

[0434] Fig. 10B 1 is a perspective schematic diagram showing the in vivo portion of an analyte sensor in one example. In some examples, the sensor further includes a third layer 114, which includes a conductive material. In another example, the third layer 114 may include a reference electrode, which may be formed by a silver-containing material applied to the second layer 104 (e.g., an insulator). The silver-containing material may include any of a variety of materials and may be in various forms, such as Ag / AgCl-polymer slurry, coating, polymer-based conductive mixture and / or, for example, commercially available ink. The third layer 114 may be treated using a sticking / dipping / coating step, such as a dip coating process using a die metering. In an exemplary example, the Ag / AgCl polymer slurry is applied to the elongated body by dipping the body (e.g., using a meniscus coating technique) and then pulling the body through the die to meter the coating to a precise thickness. In some examples, multiple coating steps are used to stack the coating to a predetermined thickness. In one example, the third (or additional layer) layer 114 includes one or more resist films, a biointerface film, and a drug release film.

[0435] Fig. 10C is a schematic side view showing the in vivo portion of a continuous multi-analyte sensor. Fig. 10A As described and Fig. 10CAs shown, the insulator 104 is disposed on (e.g., located at, covering) at least a portion of the elongated conductor 102. In some examples, the sensor is configured and arranged so that the elongated body includes a core 110 and a first conductive layer 112, and a portion of the first conductive layer 112 is exposed via a window 106 in the insulator 104. In other examples, the sensor is configured and arranged so that the elongated conductor 102 includes a core embedded in the insulator, and a portion of the core is exposed via a window in the insulator. For example, in some examples, an insulating material is applied to the elongated conductor 102 (e.g., screen printing, dip printing, inkjet printing, and / or block printing) in a configuration designed to expose a portion of the surface of the first conductive layer 112 (or the surface of the core 110). For example, the insulating material used for the insulator 104 and other insulating layers discussed herein may be formed in a pattern that does not cover a portion of the elongated body. In another example, a portion of the elongated body is masked before applying the insulating material. After applying the insulating material, the mask is removed to expose a portion of the elongated body. In another example, a series of conductive and insulating layers may be plated, dipped, or otherwise formed.

[0436] In some examples, the insulator 104 is applied as a single layer of material. In other examples, the insulator 104 is applied as two or more layers, which are composed of the same or different materials. In some examples, the insulating material includes at least one of polyurethane, polyimide and polyparaxylene. In one example, the insulating material includes polyparaxylene, which can be a favorable polymer coating due to its strength, lubricity and electrical insulation properties. Generally speaking, polyparaxylene is produced by vapor deposition and polymerization of paraxylene (or its substituted derivatives). However, any suitable insulating material can be used, such as but not limited to dielectric inks, pastes or coatings, such as fluorinated polymers, polyethylene terephthalate (PET), polyurethane, polyimide, other non-conductive polymers, etc.

[0437] In some examples, insulator 104 includes a polymer, such as a non-conductive (eg, dielectric) polymer. Dipping, spraying, vapor deposition, printing, and / or other thin film and / or thick film coating or deposition techniques may be used to deposit the insulating material on the elongated body and / or core.

[0438] Fig. 10C and Fig. 10D The results of this removal / cutting process are shown in side view / cross section. The removal process can be accomplished by various methods. In one example, the removal step is performed, for example, by laser scraping, and can be performed in a reel-to-reel process on a continuous string. For example, by removing different layers at different lengths, the removed area can be stepped ( Fig. 10D). In such a manufacturing method involving a continuous string, the sensor can be singulated after the removal step. In some examples, if the core is metal, end caps can be used, such as by dipping, spraying, heat shrinking, crimping, etc., an insulating or other isolating material onto the top. If the core is a polymer (e.g., a hydrophobic material), end caps may not be necessary. For example, in Fig. 10D In the depicted sensor, end caps (eg, made of a polymer or insulating material) or other structures may be disposed on the core (eg, if the core 110 is not insulated).

[0439] Fig.10F can be considered as being built on Fig. 10B In the general structure depicted, two or more additional layers are added to produce one or more additional electrodes. Methods for selectively removing two or more windows to produce two or more electrodes can also be used. For example, by adding another conductive layer 122' and an insulating layer 224 on the reference electrode domain 115, two electrodes (a first working electrode 114' and a second working electrode 114") can then be formed, thereby producing a multi-electrode sensor. For example, the same concept can be applied to produce a counter electrode, an electrode for measuring an additional analyte (e.g., oxygen), etc.

[0440] Figure 10G Another example is shown in which the selective removal of the layers is performed stepwise to expose the working electrodes (as shown in the exposed portions) 112, 122' and the insulators 104, 224 along the length of the elongated body. In one example, a two-electrode sensor may include a first working electrode (e.g., formed by the first conductive layer 112) configured to detect glucose and a second working electrode (e.g., formed by the second conductive layer 122') configured to detect lactate. In one example, a two-electrode sensor may include a first working electrode (e.g., formed by the first conductive layer 112) configured to detect glucose and a second working electrode (e.g., formed by the second conductive layer 122') configured to detect ketones. In another example, the two working electrodes are configured to detect the same analyte.

[0441] Fig.11 It was taken along line 11-11 Fig. 10A Schematic diagram of a cross-sectional view of an exemplary membrane configuration of a multi-analyte sensor. In one example, the membrane system includes multiple domains, such as an electrode domain 602, an interference domain 304, a transduction element domain 606 (e.g., an enzyme, an aptamer, an ion carrier, etc.) and / or a resistance domain 608, such as Fig.11As shown, and may include a high oxygen solubility domain and / or a bioprotective domain and / or a drug release domain (not shown), such as described in more detail in U.S. Patent Application Publication No. US-2005-0245799-A1, and the like. The membrane system can be independently deposited on the exposed electroactive surface using known thin film techniques (e.g., vapor deposition, spraying, electrodeposition, dipping, etc.).

[0442] Fig. 12A It is a perspective view of the in vivo portion (e.g., configured and arranged for multi-axis bending) of a single electrode, dual working electrode surface multi-analyte sensor. In this example, the insulating elongated body includes three conductive cores 110A, 110B, 110C located at (e.g., embedded, coated with) insulator 104. In this example, multiple windows are formed in the insulator and / or formed through the insulator so that each window exposes a part of the core. As a non-limiting example, window 106A is formed in the insulator so that a part of core 110A is exposed. Similarly, window 106B is formed in the insulator so that a part of core 110B is exposed. The window can be staggered and / or not staggered along the longitudinal length of the sensor. In another example, each conductive core includes an inner core and an outer core, such as described elsewhere herein.

[0443] Fig. 12B 1 is a perspective view of an in vivo portion of an analyte sensor, the in vivo portion comprising an elongated body (e.g., configured and arranged for multi-axis bending) formed by an insulator 104, a first conductive core 110A and a second conductive core 110B embedded in the insulator, and a film 108. The first conductive core is formed by platinum, platinum-iridium, gold, palladium, iridium, graphite, carbon, a conductive polymer and / or an alloy, and a first window 106A is configured and arranged to expose an electrically active portion of the first conductive core. The second conductive core is formed by a silver-containing material (e.g., silver or silver / silver chloride wire, or a silver-containing material body in the shape of a silver wire), and a second window 106B is configured and arranged to expose an electrically active portion of the second conductive core. In some examples, instead of a bulk metal wire, the first conductive core comprises an inner core and an outer core. For example, in order to reduce material costs, the inner core is formed of a material that is relatively cheaper than platinum, such as stainless steel, titanium, tantalum and / or a polymer, and the outer core is formed of a material that provides an appropriate electroactive surface, such as but not limited to platinum, platinum-iridium, gold, palladium, iridium, graphite, carbon, conductive polymers and / or alloys. In some examples, the membrane covers the exposed electroactive portion of the first conductive core. In other examples, the membrane covers the in vivo portion of the sensor. In some examples, the third conductive core is embedded in an insulator. In some examples, the third conductive core is configured and arranged as a second working electrode, which can be configured as a redundant working electrode, a non-analyte signal measurement working electrode (e.g., a non-transduction element as described below), as a counter-working electrode to detect a second analyte, etc.

[0444] Fig.13A 800 is a perspective view of an in vivo portion of another example of a multi-electrode sensor system 800 including two working electrodes and at least one reference / counter electrode. The sensor system 800 includes a first elongated body E1 and a second elongated body E2, each of which is formed by a conductive core or a core having a conductive layer deposited thereon. In this particular example, any one of an insulating layer 810, a conductive layer 820, and the aforementioned film (not shown) is deposited on the top of the elongated body E1, the elongated body E2. The insulating layer 810 separates the conductive layer 820 from the elongated body. The material selected to form the insulating layer 810 may include any insulating material described elsewhere herein, including polyurethane and polyimide. The material selected to form the conductive layer 820 may include any conductive material described elsewhere herein, including silver / silver chloride, platinum, gold, etc. Working electrodes 802', 802" are formed by removing portions of the conductive layer 820 and the insulating layer 810, thereby exposing the electroactive surfaces of the elongated bodies E1, E2, respectively. Fig. 13B A close perspective view of the distal end portion of the elongated body El, E2 is provided.

[0445] In one example, Fig.13A The two elongated bodies shown in are manufactured to have substantially the same shape and size. In some examples, the working electrodes are manufactured to have the same characteristics, thereby providing a sensor system that can provide redundancy of signal measurement results or provide unique signals representing two or more different analytes. In other examples, the working electrodes associated with the elongated bodies E1 and E2 may each have one or more characteristics that distinguish the working electrodes from each other. For example, in one example, each of the elongated bodies E1 and E2 can be a different conductive surface, so that each working electrode has different electrochemical characteristics from another working electrode. In addition, in one example, each of the elongated bodies E1 and E2 is covered with a different film, so that each working electrode has different membrane characteristics from another working electrode. For example, one of the working electrodes can have a membrane including a first transduction element, while the other working electrode can have a membrane including a layer of a transduction element or a non-transduction element, an aptamer, or a cofactor in an inactivated form. Additional sensor system configurations that may have multiple working electrodes (e.g., sensor elements) are described in U.S. Provisional Application No. 61 / 222,716, filed on July 2, 2009, and U.S. Patent Application Serial No. 12 / 829,264, filed on July 1, 2010, entitled “ANALYTE SENSOR,” each of which is incorporated herein by reference in its entirety.

[0446] Despite FIG. 13A to FIG. 13BNot shown, but in some examples, the distal ends 830', 830" of the core portions of the elongated bodies E1, E2 can be covered with an insulating material (e.g., polyurethane or polyimide). In alternative examples, the exposed core portions 830', 830" can be covered with any of the aforementioned membrane systems and / or used as additional working electrode surface area.

[0447] about FIG. 13A to FIG. 13B In the manufacture of the sensor system shown, in one example, the elongated bodies E1, E2 can be formed as elongated conductive cores, or alternatively formed as cores (conductive or non-conductive) having at least one conductive material deposited thereon. Next, an insulating layer 810 is deposited on each elongated body E1, E2. Thereafter, a conductive layer 820 is deposited on the insulating layer 810. The conductive layer 820 can be used as a reference / counter electrode and can be formed of silver / silver chloride or any other material that can be used for a reference electrode. In an alternative example, the conductive layer 820 can be formed of a different conductive material and can be used as another working electrode. After these steps, a layer removal process is performed to remove portions of the deposited layers (i.e., the conductive layer 820 and / or the insulating layer 810). Any of the techniques described elsewhere herein (e.g., laser ablation, chemical etching, grit blasting) can be used. Fig.13A and Fig. 13B In the example shown, layers of conductive layer 820 and insulating layer 810 are removed to form working electrodes 802', 802". Although in the example shown, layer removal is performed over the entire cross-sectional perimeter (e.g., circumference) of the deposited layer, it is contemplated that in other examples, layer removal may be performed over preselected segments of the cross-sectional perimeter rather than over the entire cross-sectional perimeter.

[0448] Contacts 804', 804" for providing electrical connection between the working electrode and other components of the sensor system can be formed in a similar manner. As shown, contacts 804' and contacts 804" are separated from each other to prevent electrical connection between them. Because the manufacturing process is performed on each individual slender body E1, E2 rather than a single slender body with a complex geometry, this particular sensor design (i.e., two slender bodies placed side by side) can provide manufacturing convenience compared to the manufacturing processes involved in other multi-electrode systems with other geometries.

[0449] After the conductive layer and the insulating layer are deposited on the elongated body, and after the selected portion of the deposited layer has been removed, the film is applied to at least a portion of the elongated body. In some examples, any of the above-mentioned membrane systems is applied only to the working electrode, but in other examples, any of the above-mentioned membrane systems is applied to the entire elongated body. In one example, any of the above-mentioned membrane systems is deposited on two working electrodes at the same time, while placing them together (e.g., by bundling), but in another example, any of the above-mentioned membrane systems is first deposited on each individual working electrode, and then the two working electrodes are placed together. Therefore, in one example, any of the aforementioned membrane systems is designed to have a sensitivity of about 1pA / mg / dL to about 100pA / mg / dL. In other examples, the sensitivity is about 5pA / mg / dL to 25pA / mg / dL. In another example, the sensitivity is about 4pA / mg / dL to about 7pA / mg / dL. Although not wishing to be bound by any particular theory, it is believed that a membrane system designed to have a sensitivity within the above range allows for independent measurement of one or more analyte signals in low analyte and / or low reactant / co-reactant situations. The reduced measurement accuracy within the low analyte range may be a problem due to the lower availability of the analyte to the sensor, and / or due to insufficient reactants / co-reactants necessary for the amount of the analyte being measured, and increased signal noise is shown within the high analyte range. Therefore, although not wishing to be bound by theory, it is believed that the membrane system of the present disclosure is combined with an electronic circuit design and an exposed electrochemically reactive surface area design to support analyte measurements within the picoampere range or less, which enables improved levels of resolution and accuracy to be achieved within both low and high analyte ranges.

[0450] Biointerface Film / Layer

[0451] In one example, the sensor includes a porous material disposed on portions thereof that alters the response of the recipient tissue to the sensor. In some examples, the porous material surrounding the sensor advantageously enhances sensor performance and extends sensor life in the short term by slowing or reducing cell migration into the sensor and associated degradation that would otherwise be caused by cell invasion if the sensor were directly exposed to the in vivo environment. Alternatively, the porous material can provide stabilization of the sensor in the long term via tissue ingrowth into the porous material. Suitable porous materials include silicones; polytetrafluoroethylene; expanded polytetrafluoroethylene; polyethylene-co-tetrafluoroethylene; polyolefins; polyesters; polycarbonates; biostable polytetrafluoroethylene; homopolymers, copolymers, terpolymers of polyurethanes; polypropylene (PP); polyvinyl chloride (PVC); polyvinylidene fluoride (PVDF); polyvinyl alcohol (PVA); polybutylene terephthalate (PBT); polymethyl methacrylate (PMMA); polyetheretherketone (PEEK); polyamides; polyurethanes; cellulosic polymers; poly(ethylene oxide), poly(propylene oxide) and copolymers and blends thereof; polysulfones and block copolymers thereof, including, for example, diblock, triblock, alternating, random and graft copolymers; and metals, ceramics, fibers.

[0013] Examples of the invention include, for example, polyols, hydrogel polymers, poly(2-hydroxyethyl methacrylate) (pHEMA), hydroxyethyl methacrylate (HEMA), polyacrylonitrile-polyvinyl chloride (PAN-PVC), high density polyethylene, acrylic copolymers, nylon, polyvinylidene fluoride, polyanhydrides, poly(l-lysine), poly(L-lactic acid), hydroxyethyl methacrylate, hydroxyapeptite, alumina, zirconia, carbon fibers, aluminum, calcium phosphate, titanium, titanium alloys, nitinol, stainless steel, and CoCr alloys, as described in U.S. Pat. No. 7,875,293 to Shults et al. and U.S. Pat. No. 7,192,450 to Brauker et al.

[0452] In some examples, the porous material surrounding the sensor provides unique advantages that can be used to simultaneously enhance sensor performance and extend sensor life. However, such materials can also provide advantages over a period of time (e.g., for sensor wear equal to or greater than 14, 15, or 21 days). In particular, the in vivo portion of the sensor (the portion of the sensor implanted in the recipient tissue) is (partially or completely) wrapped in a porous material. The porous material can be wrapped around the sensor (e.g., by wrapping the porous material around the sensor, or by inserting the sensor into a porous material sized to accommodate the sensor). Alternatively, the porous material can be deposited on the sensor (e.g., by electrospinning a polymer directly thereon). In yet other alternative examples, the sensor is inserted into a selected segment of a porous biomaterial. As will be appreciated by those of ordinary skill in the art, other methods of surrounding the in vivo portion of the sensor with a porous material can also be used.

[0453] The porous material surrounding the sensor advantageously slows or reduces cell migration to the sensor and associated degradation that would otherwise be caused by cell invasion if the sensor were directly exposed to the in vivo environment. That is, the porous material provides a barrier that makes cell migration to the sensor more tortuous and therefore slower (providing long-term use advantages). It is believed that this reduces or slows the sensitivity loss typically observed in sensors over time.

[0454] In the example where the porous material is a high oxygen solubility material (such as porous organosilicon), the high oxygen solubility porous material surrounds part or all of the sensor body. In some examples, a lower oxygen-glucose ratio may be sufficient to provide excess oxygen by using a high oxygen soluble domain (e.g., a material based on organosilicon or fluorocarbon) to enhance the supply / transport of oxygen to the enzyme domain and / or electroactive surface. In some examples, some signal noises that the sensor usually encounters can be attributed to hypoxia. Organosilicon has high oxygen permeability, so it promotes oxygen transport to the enzyme domain. For example, by using an organosilicon composition to enhance oxygen supply, glucose concentration may no longer be a limiting factor. In other words, if more oxygen is supplied to the enzyme and / or electroactive surface, more glucose can also be supplied to the enzyme without producing an excessive oxygen rate limit. Although not bound by any particular theory, it is believed that organosilicon materials provide enhanced biostability when compared with other polymeric materials (such as polyurethane).

[0455] In another example, the porous material also contains a bioactive agent that is released upon insertion. In one example, the porous structure provides a pathway for glucose penetration while allowing drug release / elution. In one example, when the bioactive agent is released / eluted from the porous structure, glucose transport can be increased, for example to offset any attenuation of glucose transport from the aforementioned immune response factors.

[0456] In these examples, the aforementioned porous material is a biointerface membrane including a first domain that includes a configuration that modifies the tissue response of the recipient, including cavity size, configuration, and / or overall thickness, for example, by creating fluid pockets, promoting vascularized tissue ingrowth, disrupting tissue contracture downward, resisting fibrous tissue growth adjacent to the device, and / or hindering barrier cell formation. In one example, the biointerface membrane covers at least the sensing mechanism of the sensor and can have any shape or size, including uniformly, asymmetrically, or axisymmetrically covering or surrounding the sensing mechanism or sensor.

[0457] Optionally providing a second domain of the biointerface membrane that is impermeable to cells and / or cellular processes. Optionally providing a bioactive agent incorporated into at least one of the first domain, the second domain, the sensing membrane, or other portions of the implantable device, wherein the bioactive agent is configured to alter a tissue response of a recipient. In one example, the biointerface membrane includes a bioactive agent incorporated into at least one of the first domain and the second domain of the biointerface membrane, or incorporated into the device and adapted to diffuse through the first domain and / or the second domain, so as to alter a tissue response of a recipient to the sensor implant.

[0458] Due to the small size of the sensor (sensing mechanism) of the present disclosure, some conventional methods of porous membrane formation and / or porous membrane adhesion are not suitable for forming a biointerface membrane on the sensor as described herein. Therefore, the following examples illustrate systems and methods for forming and / or adhering a biointerface membrane on a sensor with a small structure as defined herein. For example, the biointerface membrane or release membrane of the present disclosure can be formed on the sensor using techniques such as electrospinning, molding, weaving, direct writing, freeze drying, wrapping, etc.

[0459] In examples where the biointerface membrane is written directly onto the sensor, the dispenser dispenses the polymer solution using a nozzle with a valve, etc., such as described in U.S. Pat. No. 7,857,756. Generally, a variety of nozzles and / or dispensers can be used to dispense polymer materials to form woven or nonwoven fibers of the biointerface membrane.

[0460] Drug release domain-inflammatory response control

[0461] The drug release domain that can include at least one film with one or more layers can be included in the membrane system discussed herein. Generally speaking, the inflammatory response to biomaterial implants can be divided into two stages. The first stage is composed of the mobilization of mast cells and the subsequent infiltration of polymorphonuclear (PMN) cells. This stage is called the acute inflammatory stage. In the process of several days to several weeks, the chronic cell type containing the second stage inflammation replaces PMN. Macrophages and lymphocytes are dominant during this stage. Although it is not desired to be bound by any particular theory, it is believed that limiting vasodilation and / or blocking pro-inflammatory signaling, stimulating angiogenesis or inhibiting scar formation or barrier cell layer formation provides protection to scar tissue formation and / or reduces acute inflammation, thereby, for example, providing a stable platform for maintaining a foreign body response that changes continuously.

[0462] Thus, bioactive interventions can alter the foreign body response in the early weeks of foreign body capsule formation and alter the long-term behavior of the foreign body capsule. Additionally, it is believed that in some cases, the biointerface membranes and / or drug-releasing membranes of the present disclosure may benefit from bioactive interventions to overcome the sensitivity of the biointerface membranes and / or drug-releasing membranes to implant procedures, implant movement, or other factors known to otherwise cause inflammation, scarring, and impede device function in vivo.

[0463] Generally speaking, it is believed that bioactive agents that change tissue responses include anti-inflammatory agents, anti-infective agents, antiproliferative agents, antihistamines, anesthetics, inflammatory agents, growth factors, angiogenic (growth) factors, adjuvants, immunosuppressants, antiplatelet agents, anticoagulants, ACE inhibitors, cytotoxic agents, anti-barrier cell compounds, angiogenic compounds, antisense molecules, etc. In some examples, bioactive agents include S1P (sphingosine-1-phosphate), monobutyrin, cyclosporin A, antithrombin spondin 2, rapamycin (and its derivat...

Claims

1. A continuous analyte sensor device, comprising: An analyte sensor operably coupled to a signal transducer, the analyte sensor comprising at least one membrane system adjacent to the signal transducer, the at least one membrane system independently comprising: a first domain comprising at least one first transduction element; a second domain adjacent to the first domain, the second domain being the same as or different from the first domain; and At least one regeneration cofactor.

2. The continuous analyte sensor device of claim 1, wherein the analyte sensor is a multi-analyte sensor.

3. The continuous analyte sensor device of claim 2, wherein the multi-analyte analyte sensor is a glucose and ketone analyte sensor, or a glucose and creatinine analyte sensor, or a ketone and potassium ion analyte sensor.

4. The continuous analyte sensor device of any preceding claim, wherein the signal transducer comprises at least one electrode.

5. The continuous analyte sensor device according to any of the preceding claims, wherein the first domain comprises at least one first transduction element and the second domain comprises at least one second transduction element, the second transduction element being different from the first transduction element.

6. A continuous analyte sensor device according to any of the preceding claims, wherein the at least one regeneration cofactor is one or more of NAD, NADH, NAD(P)H, NAD(P)+, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), pyrroloquinoline quinone (PQQ) and their functionalized derivatives.

7. The continuous analyte sensor device of any of the preceding claims, further comprising at least one mediator present in the first domain, the second domain, or both the first domain and the second domain.

8. The continuous analyte sensor device of claim 7, wherein the mediator is one or more of 2,2′-bipyridine, poly-110-phenanthroline-5,6-dione, polyvinylferrocene, hexacyanoferric acid, phthalocyanine or their organometallic compounds, organometallic compounds of osmium or ruthenium and their functionalized derivatives, and complexes of one or more transition metals with one or more polymers or ligands and their salts.

9. A continuous analyte sensor device according to any one of claims 7 to 8, wherein the first domain includes the at least one mediator and the at least one first transduction element, and the second domain includes the at least one regeneration cofactor, or wherein the first domain includes the at least one regeneration cofactor and the at least one first transduction element, and the second domain includes the at least one mediator.

10. The continuous analyte sensor device of claim 5, wherein the at least one first transduction element and the at least one second transduction element are independently dehydrogenases, reductases, kinases, peroxidases, esterases, (amido) hydrolases, oxidases, or combinations thereof.

11. The continuous analyte sensor device of claim 5, wherein the at least one first transduction element and the at least one second transduction element are independently β-hydroxybutyrate dehydrogenase, alcohol dehydrogenase, lipase, amide hydrolase, glycerol kinase, creatinine kinase, creatine amide hydrolase, alcohol oxidase, cholesterol oxidase, galactose oxidase, choline oxidase, glutamate oxidase, glycerol-3-phosphate oxidase, bilirubin oxidase, urease, pyruvate oxidase, xanthine oxidase, glucose oxidase, lactate oxidase, sarcosine oxidase, malate dehydrogenase, formaldehyde dehydrogenase, glutathione reductase, glutathione peroxidase, 3-hydroxysteroid dehydrogenase, NADH oxidase, or a combination thereof.

12. The continuous analyte sensor device of claim 5, wherein the at least one first transduction element is β-hydroxybutyrate dehydrogenase and the at least one second transduction element is NADH oxidase.

13. The continuous analyte sensor device of claim 4, wherein: The at least one electrode comprises platinum or palladium; an interference domain deposited on the at least one electrode; The first domain is adjacent to the interfering domain, the first domain comprising β-hydroxybutyrate dehydrogenase, NADH oxidase, and the cofactor; and The second domain is adjacent to the first domain, the second domain comprising a polyvinylpyridine polymer or copolymer; Wherein the continuous analyte sensor device is configured to provide a continuous analyte signal in the absence of a transition metal-containing mediator.

14. The continuous analyte sensor device of claim 13, wherein the at least one regeneration cofactor is NAD.

15. The continuous analyte sensor device of any one of claims 13 or 14, wherein the interference domain is configured to block diffusion of at least one of acetaminophen, ascorbic acid, bilirubin, cholesterol, creatinine, dopamine, ephedrine, ibuprofen, L-dopa, methyldopa, salicylate, tetracycline, tolbutamide, tolbutamide, triglycerides, and uric acid from the electrode.

16. The continuous analyte sensor device of any one of claims 13 or 15, wherein the interference domain comprises polyurethane, polyurethane-zwitterionic polymer, polymer with ionic side groups, NAFION TM , chitosan, cellulose, alternating layers of polyallylamine and polyacrylic acid, or combinations or blends thereof.

17. The continuous analyte sensor device of any preceding claim, wherein the first domain or the second domain comprises an amphiphilic polymer or copolymer.

18. The continuous analyte sensor device of any preceding claim, wherein the first domain or the second domain comprises a heterocyclic polymer or copolymer, or an at least partially quaternized heterocyclic polymer or copolymer.

19. The continuous analyte sensor device of any preceding claim, further comprising a transmitter configured to wirelessly transmit data to a paired display device or therapy delivery device.

20. The continuous analyte sensor device of any preceding claim, wherein the continuous analyte sensor device is sterile.

21. A continuous multi-analyte sensor device, the continuous multi-analyte sensor device comprising: An in-built multi-analyte sensor operably coupled to a signal transducer, the multi-analyte sensor comprising at least one membrane system adjacent to the signal transducer, the at least one membrane system independently comprising: a first layer comprising at least one first transduction element; and A second layer adjacent to the first layer, the second layer being the same as or different from the first layer.

22. The continuous multi-analyte sensor device of claim 21, wherein the signal transducer comprises at least one electrode.

23. The continuous multi-analyte sensor device of claim 22, wherein the at least one electrode comprises a first working electrode surface and a second working electrode surface vertically, horizontally, or circumferentially spaced apart from the first working electrode surface.

24. The continuous multi-analyte sensor device of claim 23, wherein the first layer is adjacent to the first working electrode surface.

25. The continuous multi-analyte sensor device of claim 23, wherein the second layer is adjacent to the second working electrode surface.

26. A continuous multi-analyte sensor device according to claim 23, wherein at least a portion of the first layer is adjacent to at least a portion of the first working electrode surface, and at least a portion of the second layer is separated from at least a portion of the first working electrode surface farther, vertically, horizontally or circumferentially than the portion of the first layer.

27. The continuous multi-analyte sensor device of claim 21, wherein the second layer comprises at least one second transduction element, the second transduction element being different from the first transduction element.

28. The continuous multi-analyte sensor device of claim 27, further comprising at least one of a mediator and a regeneration cofactor present in the first layer, the second layer, or both the first layer and the second layer, wherein the at least one mediator is operably associated with the at least one first transduction element or the at least one second transduction element.

29. The continuous multi-analyte sensor device of any of the preceding claims, wherein the first layer comprises the at least one mediator and the at least one first transduction element, and the second layer comprises at least one regeneration cofactor.

30. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the second layer includes the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

31. The continuous multi-analyte sensor device of any of the preceding claims, wherein the first layer comprises the at least one regeneration cofactor and the at least one first transduction element, and the second layer comprises the at least one mediator.

32. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the second layer comprises the at least one second transduction element, wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

33. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the first layer includes the at least one mediator, the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is away from the first working electrode surface.

34. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the first layer includes the at least one first transduction element, and the second layer includes the at least one regeneration cofactor, the at least one mediator and the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is away from the first working electrode surface.

35. The continuous multi-analyte sensor device of any of the preceding claims, wherein the first layer comprises the at least one mediator and the at least one first transduction element, and the second layer comprises the at least one regeneration cofactor.

36. The continuous multi-analyte sensor device of any of the preceding claims, wherein the first layer comprises the at least one regeneration cofactor and the at least one first transduction element, and the second layer comprises the at least one mediator.

37. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the first layer includes the at least one mediator, the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is close to the second working electrode surface.

38. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, the at least one mediator and the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is close to the second working electrode surface.

39. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the at least one regeneration cofactor is one or more of NAD, NADH, NAD(P)H, NAD(P)+, ATP, flavin adenine dinucleotide (FAD), magnesium (Mg++), pyrroloquinoline quinone (PQQ), pyrroloquinoline quinone (PQQ) and their functionalized derivatives.

40. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the mediator or the at least one regeneration cofactor is covalently, electrostatically, ionically associated with one or more of the first layer, the second layer, or the third layer, or is physically retained or absorbed by one or more of the first layer, the second layer, or the third layer.

41. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the mediator or at least one regeneration cofactor is covalently, electrostatically, ionically associated with the one or more working electrode surfaces, or is physically retained or absorbed by the one or more working electrode surfaces.

42. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the second layer comprises the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

43. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the second layer comprises the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

44. The continuous multi-analyte sensor device of any of the preceding claims, wherein the first layer or the second layer comprises a polymer.

45. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the polymer is a polyolefin, polystyrene, polyoxymethylene, polysiloxane, polyether, polyacrylate, polymethacrylate, polyester, polycarbonate, polyamide, polypyridine, poly(pyridine-styrene) copolymer, poly(ether ketone), poly(etherimide), polyurethane, polyurethane urea, polycarbonate-polyurethane copolymer or a blend thereof.

46. ​​The continuous multi-analyte sensor device of any of the preceding claims, further comprising at least one third transduction element present in at least one of the first, second and third layers.

47. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the first layer has a first diffusion resistance to one or more analytes or one or more substrate reaction products, and the second layer has a second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products, wherein the second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products is substantially the same as or different from the first diffusion resistance.

48. The continuous multi-analyte sensor device of claim 47, wherein the one or more analytes comprise glucose, lactose, glycerol, beta-hydroxybutyrate, creatinine, creatine, alcohol, urea, uric acid, cholesterol, bilirubin, glutathione, urea, sodium, potassium, or glutamate.

49. The continuous multi-analyte sensor device of any of the preceding claims, wherein the at least one first transduction element and the at least one second transduction element are independently selected from dehydrogenases, reductases, kinases, peroxidases, esterases, (amido) hydrolases, and oxidases.

50. The continuous multi-analyte sensor device of any of the preceding claims, wherein the at least one first transduction element and the at least one second transduction element each have a substrate and produce a reaction product with the substrate and provide a clinical value related to the health condition of a mammal.

51. The continuous multi-analyte sensor device of claim 50, wherein the substrate or the reaction product is selected from hydrogen peroxide, creatine, acetoacetate, dihydroxyacetone, oxygen or an aldehyde.

52. The continuous multi-analyte sensor device of any of the preceding claims, wherein the at least one first transduction element and the at least one second transduction element are β-hydroxybutyrate dehydrogenase, alcohol dehydrogenase, lipase, amide hydrolase, glycerol kinase, creatinine kinase, creatine amide hydrolase, alcohol oxidase, cholesterol oxidase, galactose oxidase, choline oxidase, glutamate oxidase, glycerol-3-phosphate oxidase, bilirubin oxidase, ascorbate oxidase, urate oxidase, urease, pyruvate oxidase, xanthine oxidase, glucose oxidase, lactate oxidase, sarcosine oxidase, malate dehydrogenase, formaldehyde dehydrogenase, glutathione reductase, glutathione peroxidase, 3-hydroxysteroid dehydrogenase, or horseradish peroxidase.

53. A continuous multi-analyte sensor device according to any of the preceding claims, wherein the mediator is one or more of 2,2′-bipyridine, poly-110-phenanthroline-5,6-dione, polyvinylferrocene, hexacyanoferric acid, phthalocyanine or their organometallic compounds, organometallic compounds of osmium or ruthenium and their functionalized derivatives, and complexes of one or more transition metals with one or more polymers or ligands and their salts.

54. A continuous multi-analyte sensor device according to any of the preceding claims, further comprising a transmitter configured to wirelessly transmit data to a paired display device or treatment delivery device so that multiple analyte parameters are evaluated in parallel.

55. A continuous analyte sensor device, the continuous analyte sensor device comprising: An in-built mediated analyte sensor operably coupled to a signal transducer, the mediated analyte sensor comprising at least one membrane system adjacent to the signal transducer, the at least one membrane system independently comprising: a first layer comprising at least one first transduction element; a second layer adjacent to the first layer, the second layer being the same as or different from the first layer; at least one mediator; and The mediated system interference domain comprises at least one oxidase, at least one peroxidase, a catalase, or a combination thereof.

56. The continuous analyte sensor device of claim 55, wherein the inline mediated analyte sensor is a multi-analyte sensor.

57. The continuous analyte sensor device of any one of claims 55 to 56, wherein the in-line mediated analyte sensors are glucose and ketone analyte sensors.

58. The continuous analyte sensor device of any one of claims 55 to 57, wherein the in-line mediated analyte sensors are glucose and creatinine analyte sensors.

59. The continuous analyte sensor device of any one of claims 55 to 58, wherein the in-line mediated analyte sensor is a glucose and alcohol analyte sensor.

60. The continuous analyte sensor device of any one of claims 55 to 59, wherein the signal transducer comprises at least one electrode.

61. The continuous analyte sensor device of claim 60, wherein the at least one electrode comprises a first working electrode surface and a second working electrode surface vertically, horizontally, or circumferentially spaced apart from the first working electrode surface.

62. The continuous analyte sensor device of claim 60, wherein the first layer is adjacent to the first working electrode surface.

63. The continuous analyte sensor device of claim 60, wherein the second layer is adjacent to the second working electrode surface.

64. A continuous analyte sensor device according to claim 60, wherein at least a portion of the first layer is adjacent to at least a portion of the first working electrode surface, and at least a portion of the second layer is separated from at least a portion of the first working electrode surface farther, vertically, horizontally or circumferentially than the portion of the first layer.

65. The continuous analyte sensor device of claim 60, wherein the second layer comprises the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

66. The continuous analyte sensor device of claim 60, wherein the second layer comprises the at least one second transduction element, and wherein at least a portion of the first layer is proximal to the first working electrode surface and at least a portion of the second layer is distal to the first working electrode surface.

67. The continuous analyte sensor device of any one of claims 55 to 66, wherein the first layer comprises at least one first transduction element and the second layer comprises at least one second transduction element, the second transduction element being different from the first transduction element.

68. The continuous analyte sensor device of any one of claims 55 to 67, wherein the at least one first transduction element and the at least one second transduction element each have a substrate and produce a reaction product with the substrate and provide a clinical value related to the health condition of the mammal.

69. The continuous analyte sensor device of any one of claims 55 to 68, further comprising at least one regeneration co-factor present in the first layer, the second layer, or both the first layer and the second layer.

70. The continuous analyte sensor device of claim 69, wherein the first layer comprises the at least one mediator and the at least one first transduction element, and the second layer comprises the at least one regeneration cofactor.

71. The continuous analyte sensor device of claim 69, wherein the first layer comprises the at least one regeneration cofactor and the at least one first transduction element, and the second layer comprises the at least one mediator.

72. A continuous analyte sensor device according to claim 69, wherein the first layer includes the at least one mediator, the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is away from the first working electrode surface.

73. A continuous analyte sensor device according to claim 69, wherein the first layer includes the at least one mediator, the at least one regeneration cofactor and the at least one first transduction element, and the second layer includes the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is close to the second working electrode surface.

74. A continuous analyte sensor device according to claim 69, wherein the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, the at least one mediator and the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is away from the first working electrode surface.

75. A continuous analyte sensor device according to claim 69, wherein the first layer includes the at least one first transduction element and the second layer includes the at least one regeneration cofactor, the at least one mediator and the at least one second transduction element, wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is close to the second working electrode surface.

76. A continuous analyte sensor device according to any one of claims 55 to 75, wherein the second layer includes the at least one second transduction element, and wherein at least a portion of the first layer is close to the first working electrode surface and at least a portion of the second layer is away from the first working electrode surface.

77. The continuous analyte sensor device of any one of claims 55 to 76, wherein the second layer comprises the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

78. The continuous analyte sensor device of any one of claims 55 to 77, wherein the second layer comprises the at least one second transduction element, wherein at least a portion of the first layer is proximate to the first working electrode surface and at least a portion of the second layer is proximate to the second working electrode surface.

79. The continuous analyte sensor device of any one of claims 55 to 78, further comprising a third layer adjacent to the second layer.

80. The continuous analyte sensor device of any one of claims 55 to 79, further comprising at least one third transduction element present in at least one of the first layer, the second layer, and the third layer.

81. A continuous analyte sensor device according to any one of claims 55 to 80, wherein the first layer has a first diffusion resistance to one or more analytes or one or more substrate reaction products, and the second layer has a second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products, wherein the second diffusion resistance to the one or more analytes or the one or more enzyme substrate reaction products is substantially the same as or different from the first diffusion resistance.

82. The continuous analyte sensor device of any one of claims 55 to 81, wherein the at least one first transduction element and the at least one second transduction element are independently dehydrogenases, reductases, kinases, peroxidases, esterases, (amido) hydrolases, oxidases, or combinations thereof.

83. The continuous analyte sensor device of any one of claims 55 to 82, wherein the at least one first transduction element and the at least one second transduction element are independently β-hydroxybutyrate dehydrogenase, alcohol dehydrogenase, lipase, amide hydrolase, glycerol kinase, creatinine kinase, creatine amide hydrolase, alcohol oxidase, cholesterol oxidase, galactose oxidase, choline oxidase, glutamate oxidase, glycerol-3-phosphate oxidase, bilirubin oxidase, urease, pyruvate oxidase, xanthine oxidase, glucose oxidase, lactate oxidase, sarcosine oxidase, malate dehydrogenase, formaldehyde dehydrogenase, glutathione reductase, glutathione peroxidase, 3-hydroxysteroid dehydrogenase, or a combination thereof.

84. A continuous analyte sensor device according to any one of claims 55 to 83, wherein the mediator is one or more of 2,2′-bipyridine, poly-110-phenanthroline-5,6-dione, polyvinylferrocene, hexacyanoferric acid, phthalocyanine or their organometallic compounds, organometallic compounds of osmium or ruthenium and their functionalized derivatives, and complexes of one or more transition metals with one or more polymers or ligands and their salts.

85. The continuous analyte sensor apparatus of any one of claims 55 to 84, wherein the at least one oxidase is ascorbate oxidase or urate oxidase.

86. The continuous analyte sensor apparatus of any one of claims 55 to 85, wherein the at least one peroxidase is horseradish peroxidase.

87. The continuous analyte sensor device of any one of claims 55 to 86, wherein the mediated system interference domain comprises at least one polymer.

88. A continuous analyte sensor device according to any one of claims 55 to 87, wherein at least one of the polymers is a polyolefin, a polystyrene, a polyoxymethylene, a polysiloxane, a polyether, a polyacrylate, a polymethacrylate, a polyester, a polycarbonate, a polyamide, a polypyridine, a poly(pyridine-styrene) copolymer, a poly(ether ketone), a poly(etherimide), a polyurethane, a polyurethane urea, a polycarbonate-polyurethane copolymer, polyethylene vinyl acetate or a blend thereof.

89. The continuous analyte sensor device of any one of claims 55 to 88, further comprising at least one of an electrode domain, an enzyme domain, a resistance domain, and an interference membrane.

90. The continuous analyte sensor device of any one of claims 55 to 89, wherein the mediated system interference domain is present in the electrode domain.

91. The continuous analyte sensor device of any one of claims 55 to 90, wherein the mediated system interference domain is directly adjacent to the electrode domain.

92. The continuous analyte sensor device of any one of claims 55 to 91, wherein the mediated system interference domain is present in the enzyme domain.

93. The continuous analyte sensor device of any one of claims 55 to 92, wherein the mediated system interference domain is directly adjacent to the enzyme domain.

94. The continuous analyte sensor device of any one of claims 55 to 93, wherein the mediated system interference domain is present in the resistance domain.

95. The continuous analyte sensor device of any one of claims 55 to 94, wherein the mediated system interference domain is directly adjacent to the resistance domain.

96. The continuous analyte sensor device of any one of claims 55 to 95, wherein the mediated system interference domain is present in the interfering membrane.

97. The continuous analyte sensor device of any one of claims 55 to 96, wherein the mediated system interference domain is directly adjacent to the interfering membrane.

98. A continuous analyte sensor device according to any one of claims 55 to 97, further comprising a transmitter configured to wirelessly transmit data to a paired display device or treatment delivery device such that at least two analyte parameters are evaluated in parallel.

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