Systems, devices, and methods for analyte monitoring

Abstract

Analyte sensors are being increasingly employed for monitoring various analytes in vivo. Analyte sensors may feature enhancements to address signals obtained from interferent species. Some analyte sensors may comprise a substrate having a planar surface, a working electrode disposed on the surface of the substrate and comprising an active area, the active area having an analyte-responsive enzyme, a reference electrode disposed on the surface of the substrate and separated by a distance from the working electrode, and at least one barrier disposed between the working electrode and the reference electrode, wherein the barrier includes an ablated zone and is configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the surface of the substrate.

Description

[0001] SYSTEMS, DEVICES, AND METHODS FOR ANALYTE MONITORING

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit, under 35 U.S.C. § 119(e), of U.S. Provisional Patent Application No. 63 / 586,660, filed September 29, 2023, which is incorporated herein by reference in its entirety and for all purposes.

[0004] BACKGROUND

[0005] The detection of various analytes within an individual can sometimes be vital for monitoring the condition of their health. Deviation from normal analyte levels can often be indicative of a number of physiological conditions. Glucose levels, for example, can be particularly important to detect and monitor in diabetic individuals. By monitoring glucose levels with sufficient regularity, a diabetic individual may be able to take corrective action (e.g., by injecting insulin to lower glucose levels or by eating to raise glucose levels) before significant physiological harm occurs. Monitoring of other analytes may be desirable for other various physiological conditions. Monitoring of multiple analytes may also be desirable in some instances, particularly for comorbid conditions resulting in simultaneous dysregulation of two or more analytes in combination with one another.

[0006] Many analytes represent intriguing targets for physiological analyses, provided that a suitable detection chemistry can be identified. To this end, in vivo analyte sensors configured for assaying various physiological analytes have been developed and refined over recent years, many of which utilize enzyme-based detection strategies to facilitate detection specificity. Indeed, in vivo analyte sensors utilizing a glucose-responsive enzyme for monitoring blood glucose levels are now in common use among diabetic individuals. In vivo analyte sensors for other analytes are in various stages of development, including in vivo analyte sensors capable of monitoring multiple analytes. Poor sensitivity for low- abundance analytes may be especially problematic for some analyte sensors, particularly due to background signal arising from interaction of an interferent with a working electrode or other analyte sensing chemistry components. Accordingly, there remains a need for analyte sensors having improved sensitivity. SUMMARY OF THE DISCLOSURE

[0007] Aspects of the invention are set out in the independent claims and preferred features are set out in the dependent claims. Features of one aspect may be applied to each aspect alone or in combination with other features.

[0008] The current disclosure is directed to analyte sensors and systems and methods for manufacturing an analyte sensor configured to measure analytes in the interstitial fluid of a user. The analyte sensor system can include a substrate having a planar surface, a working electrode disposed on the planar surface of the substrate and comprising an active area with an analyte-responsive enzyme, and a reference electrode disposed on the planar surface of the substrate at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode, and at least one barrier disposed between the working electrode and the reference electrode, wherein the barrier includes an ablated zone and is configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the surface of the substrate

[0009] In some embodiments, the at least one barrier can include at least one of a jetted ink barrier disposed on the region or a laser ablated barrier formed from the planar surface of the region. According to some embodiments, the substrate can include a distal portion and a proximal portion, the at least one barrier along the distal portion can include the laser ablated barrier, and the at least one barrier along the proximal portion can include the jetted ink barrier. In another embodiment, the at least one barrier along the distal portion can include the jetted ink barrier and the at least one barrier along the proximal portion can include the laser ablated barrier. In yet another embodiment, the substrate can include a distal portion and a proximal portion such that the at least one barrier along the distal portion includes at least one of the jetted ink barrier or the laser ablated barrier and the at least one barrier along the proximal portion is at least one of the jetted ink barrier or the laser ablated barrier.

[0010] In some embodiments, the at least one barrier can include the jetted ink barrier disposed on the region. Additionally, a portion of the jetted ink barrier can be ablated.

[0011] In some embodiments, the at least one barrier can abut at least one of the working electrode or the reference electrode along a single side thereof. The at least one barrier can have a height dimension from the planar surface greater than a height dimension from the planar surface of either the working electrode or the reference electrode. In some embodiments the height dimension of the at least one barrier can be between 5 gm and 50 gm. Additionally, each of the at least one barrier, working electrode, and reference electrode respectively have a width, wherein the width of the at least one barrier does not overlap with the width of either the working electrode or the reference electrode.

[0012] In some embodiments, the substrate can include a distal portion and a proximal portion, the working electrode can include a first conductive path disposed on the distal portion of the substrate and a first head disposed on the proximal portion of the substrate, the reference electrode can include a second conductive path disposed on the distal portion of the substrate and disposed at a first distance to the first conductive path, and a second head disposed on the proximal portion of the substrate and disposed at a second distance to the second head. Furthermore, the at least one barrier can include a first barrier and a second barrier, the first barrier abuts the first conductive path, and the second barrier abuts the second conductive path. Furthermore, as is disclosed herein, the at least one barrier can include a first barrier and a second barrier, the first conductive path can include a first conductive path length, the second conductive path can include a second conductive path length, the first barrier can include a first barrier length approximately equal to the first conductive path length, and the second barrier can include a second barrier length approximately equal to the second conductive path length.

[0013] In some embodiments, the analyte sensor system can include a counter electrode disposed on the surface of the substrate and electrically isolated from each of the working electrode and the reference electrode on the surface of the substrate. In yet another embodiment, the counter electrode can include a third conductive path disposed on the distal portion of the substrate and a third head disposed on the proximal portion of the substrate, and the at least one barrier can further include a third barrier abutting the third conductive path. According to embodiments disclosed herein, the at least one barrier can further include a fourth barrier adjacent abutting one of the first conductive path and the second conductive path, the fourth barrier having a fourth barrier length approximately equal to the first conductive path length or the second conductive path length, respectively. In some embodiments, a distance between the first barrier and the second barrier can range between 20gm and 50gm. In yet another embodiment, a width of the first barrier can range between 15gm and 30gm and a width of the second barrier can range between 15gm and 30gm.

[0014] As disclosed herein, according to some embodiments, a portion of the region located between the first barrier and the second barrier, and / or the third and fourth barriers, respectively, can be the ablated zone. According to other embodiments, the barrier can include a repellent surface and / or a carbon eroding acid. In yet another embodiment, a first portion of the surface located between the first barrier and the second barrier is connected to a second portion of the surface located between the third barrier and the fourth barrier at the distal portion of the surface by a fifth barrier. In some embodiments, the reference electrode can be a counter electrode According to other embodiments, a membrane is disposed over the substrate configured to control a rate of transfer of an analyte therethrough. In some embodiments, the membrane includes at least one layer of a uniform thickness dimension.

[0015] As disclosed herein, methods for manufacturing an analyte sensor system according to the above embodiments are also disclosed. In particular, the method includes providing a substrate having a planar surface; printing at least one barrier on the planar surface; disposing, on the planar surface of the substrate, a working electrode thereon and disposing an analyte-responsive enzyme on an active area of the working electrode; and disposing, on the planar surface of the substrate, a reference electrode thereon, wherein a region of the planar surface separates the reference electrode and the working electrode, and wherein the at least one barrier is disposed between the working electrode and the reference electrode and configured to electrically isolate the working electrode from the reference electrode.

[0016] In other embodiments, a method of producing an analyte sensor system is provided comprising: providing a substrate having a surface; disposing, on the surface, a layer having an analyte-responsive enzyme; removing at least a portion of the layer to create at least one barrier, wherein the at least one barrier electrically isolates a working electrode of the substrate from a reference electrode of the substrate, wherein the working electrode has an active area with the analyte-responsive enzyme thereon.

[0017] In yet another embodiment, an analyte sensor system can include a substrate having a planar surface, a working electrode disposed on the planar surface of the substrate and including an active area, the active area having an analyte-responsive enzyme, a reference electrode disposed on the planar surface of the substrate at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode, and at least one barrier disposed in the region between the working electrode and the reference electrode and abutting at least one of the working electrode and the reference electrode, wherein each of the at least one barrier, working electrode, and reference electrode have a respective width, wherein the width of the at least one barrier does not overlap with the width of either the working electrode or the reference electrode, the at least one barrier configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the planar surface of the substrate.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure.

[0020] FIG. 1 shows a diagram of an illustrative sensing system that may incorporate an analyte sensor of the present disclosure.

[0021] FIG. 2 shows a diagram of an analyte sensor having a plurality of electrodes disposed on a single dielectric layer.

[0022] FIG. 3 (prior art) shows cross-sectional diagrams of analyte sensors comprising two active areas according to known configurations.

[0023] FIG. 4 (prior art) shows a cross-sectional diagram of an analyte sensor comprising two working electrodes, each having an active area present thereon according to known configurations.

[0024] FIG. 5 shows an image of electron microscopy of laser ablated isolated substrate regions.

[0025] FIG. 6 is an image of light microscopy of an analyte sensor having printed barriers.

[0026] DETAILED DESCRIPTION

[0027] The present disclosure generally describes analyte sensors suitable for in vivo use and, more specifically, analyte sensors featuring one or more enhancements for improving analyte sensor sensitivity and accuracy, and methods for production and use thereof.

[0028] Such enhancements may include disposing one or more electrodes on a single sensor surface, the one or more electrodes being electrically isolated by at least one barrier disposed on the single sensor surface, to minimize the variability of the sensor and membrane thickness and improve sensor performance. For example, the structure of the single sensor surface according to the disclosed subject matter has less variation in depth in comparison with multilayered sensor surfaces, which in turn provides for a more even platform for membrane deposition thereon. The single sensor surface structure allows for a more uniform thickness of the membrane thereupon, which can provide greater control over the flow rate of the analyte to the sensor. The analyte sensors described herein comprise a sensor tail comprising at least one working electrode, particularly a carbon working electrode, and an active area disposed thereupon. A mass transport limiting membrane can be disposed upon the carbon working electrode (z.e., disposed upon both the active area and any extraneous carbon working electrode lacking the active area forming the sensor tail).

[0029] In contrast, with some existing sensors as shown in the prior art figures of FIGS. 3 and 4, such analyte sensor may include electrodes on different sides of a substrate or multiple stacked electrodes which are electrically isolated by dielectric layers. This stacked- layer configuration of the prior art can result in a thicker underlying platform and thus result in a varied membrane thickness across the length of the sensor tail. Increased variability of the membrane thickness can correlate to decreased sensor performance. Therefore, minimizing the variability of the membrane thickness by disposing the at least one electrode on a single surface can increase sensor performance, as demonstrated by the disclosed subject matter.

[0030] The disclosed subject matter provides for a membrane of less variable thickness at least by way of a thinner underlying substrate due to a reduced number of printed layers. Embodiments of the disclosed subject matter control the rate of transfer for a given analyte through the membrane for an appropriate sensitivity such as limiting the electrical response to a usable level and allow for enough signal to be detectable / processable by the electronic components of the system and to be usable in determining accuracy and a suitable relationship between the analyte concentration and the sensor signal. Further, the rate of transfer can be controlled with the disclosed subject matter in order to minimize molecular degradation of the sensing components. Thus, embodiments of the disclosed subject matter prevent degradation stemming from a number of sources, such as degradation resulting from a rapid transfer of analyte and resulting elevated electrochemical redox reactions including but are not limited to; spatial interferences at the active site leading to molecular damage of the enzyme (“wear and tear”), temporal pH changes, non-competitive inhibition of the enzyme active site. Accordingly, the controlled / limited influx of analyte of the disclosed subject matter allows for a relatively high sensing capacity (such as presence of available enzyme active sites / absence of reaction limiting factors) to be maintained in excess at orders of magnitude higher than the analyte sensing requirements, essentially keeping the work rate of individual enzymes low by having many enzymes to share the burden of catalyzing the analyte.

[0031] Particular details and further advantages of each type of enhancement are described in further detail herein. Depending on particular needs, the analyte sensors of the present disclosure may be configured to detect one analyte or multiple analytes simultaneously or near simultaneously.

[0032] Analyte sensors employing enzyme-based detection are commonly used for assaying a single analyte, such as glucose, due to the frequent specificity of enzymes for a particular substrate or class of substrate. Analyte sensors employing both single enzymes and enzyme systems comprising multiple enzymes acting in concert may be used for this purpose. As used herein, the term “in concert,” and grammatical variants thereof, refers to a coupled enzymatic reaction, in which the product of a first enzymatic reaction becomes the substrate for a second enzymatic reaction, and the second enzymatic reaction or a subsequent enzymatic reaction serves as the basis for measuring the concentration of an analyte. Moreover, a combination of enzymes and / or enzyme systems may be employed to detect more than one analyte type. Using an in vivo analyte sensor featuring an enzyme or enzyme system to promote detection may be particularly advantageous to avoid the frequent withdrawal of bodily fluid that otherwise may be required for analyte monitoring to take place.

[0033] In vivo analyte sensors monitor one or more analytes in a biological fluid of interest such as dermal fluid, interstitial fluid, plasma, blood, lymph, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage, amniotic fluid, or the like. Such fluids may comprise one or more interferents that can react with the working electrode of the analyte sensor, either directly on the working electrode itself (e.g., carbon working electrode) or with one or more sensing chemistry components disposed thereupon. As used herein, the term “interferent,” and grammatical variants thereof, refers to any electroactive species present that are not an analyte(s) of interest (e.g., in vivo electroactive species that are not an analyte(s) of interest). Examples include, but are not limited to, ascorbic acid (vitamin C and also referred to as ascorbate), glutathione, uric acid, paracetamol (acetaminophen), isoniazid, salicylate, and the like, and any combination thereof. The reaction of these interferents with the working electrode can create an electrochemical signal that is inseparable or not easily separable from signal originating from the analyte of interest, which may complicate the accurate detection of such analytes, particularly those in low- abundance (e.g., low-to sub-millimolar concentrations). The electrochemical signal generated by an interferent may be particularly problematic as the signal from the interferent becomes closer in magnitude to that of the signal from the target analyte. This may occur, for example, when the concentration of the interferent approaches or exceeds the concentration of the analyte of interest. Some interferents are ubiquitous in vivo and are not easily avoided. Therefore, techniques to minimize their influence during in vivo analyses may be highly desirable.

[0034] The present disclosure provides analyte sensor enhancements that, either alone or in combination with other enhancements, may improve detection sensitivity for both single analytes and multiple analytes in combination with one another, as explained in further detail hereinbelow. Namely, the present disclosure provides analyte sensors having multiple electrodes disposed on a single sensor surface, the multiple electrodes being electrically isolated by a barrier.

[0035] Before describing the analyte sensors of the present disclosure and their enhancements in further detail, a brief overview of suitable in vivo analyte sensor configurations and sensor systems employing the analyte sensors will be provided first so that the embodiments of the present disclosure may be better understood. FIG. 1 shows a diagram of an illustrative sensing system that may incorporate an analyte sensor of the present disclosure. As shown, sensing system 100 includes sensor control device 102 and reader device 120 that are configured to communicate with one another over local communication path or link 140, which may be wired or wireless, uni- or bi-directional, and encrypted or non-encrypted. Reader device 120 may constitute an output medium for viewing analyte concentrations and alerts or notifications determined by sensor 104 or a processor associated therewith, as well as allowing for one or more user inputs, according to some embodiments. Reader device 120 may be a multi-purpose smartphone or a dedicated electronic reader instrument. While only one reader device 120 is shown, multiple reader devices 120 may be present in certain instances.

[0036] Reader device 120 may also be in communication with remote terminal 170 and / or trusted computer system 180 via communication path(s) / link(s) 141 and / or 142, respectively, which also may be wired or wireless, uni- or bi-directional, and encrypted or non-encrypted. Reader device 120 may also or alternately be in communication with network 150 (e.g., a mobile telephone network, the internet, or a cloud server) via communication path / link 151. Network 150 may be further communicatively coupled to remote terminal 170 via communication path / link 152 and / or trusted computer system 180 via communication path / link 153. Alternately, sensor 104 may communicate directly with remote terminal 170 and / or trusted computer system 180 without an intervening reader device 120 being present. For example, sensor 104 may communicate with remote terminal 170 and / or trusted computer system 180 through a direct communication link to network 150, according to some embodiments, as described in U.S. Patent Application Publication 2011 / 0213225 and incorporated herein by reference in its entirety.

[0037] Any suitable electronic communication protocol may be used for each of the communication paths or links, such as near field communication (NFC), radio frequency identification (RFID), BLUETOOTH® or BLUETOOTH® Low Energy protocols, WiFi, or the like. Remote terminal 170 and / or trusted computer system 180 may be accessible, according to some embodiments, by individuals other than a primary user who have an interest in the user’s analyte levels. Reader device 120 may comprise display 122 and optional input component 121. Display 122 may comprise a touch-screen interface, according to some embodiments.

[0038] Sensor control device 102 includes sensor housing 103, which may house circuitry and a power source for operating sensor 104. Optionally, the power source and / or active circuitry may be omitted. A processor (not shown) may be communicatively coupled to sensor 104, with the processor being physically located within sensor housing 103 or reader device 120. Sensor 104 protrudes from the underside of sensor housing 103 and extends through adhesive layer 105, which is adapted for adhering sensor housing 103 to a tissue surface, such as skin, according to some embodiments.

[0039] Sensor 104 is adapted to be at least partially inserted into a tissue of interest, such as within the dermal or subcutaneous layer of the skin. Alternatively, sensor 104 may be adapted to penetrate the epidermis. Still further alternatively, sensor 104 may be disposed superficially and not penetrate a tissue, such as when assaying one or more analytes in perspiration upon the skin. Sensor 104 may comprise a sensor tail of sufficient length for insertion to a desired depth in a given tissue. The sensor tail may comprise at least one working electrode and an active area comprising an enzyme or enzyme system configured for assaying one or more analytes of interest.

[0040] A counter electrode may be present in combination with the at least one working electrode, optionally in further combination with a reference electrode. Particular electrode configurations upon the sensor tail are described in more detail below in reference to FIGS. 2, 5 and 6. One or more enzymes in the active area of the electrode may be covalently bonded to a polymer comprising the active area, according to various embodiments. Alternately, enzymes may be non-covalently associated within the active area, such as through encapsulation or physical entrainment. The one or more analytes may be monitored in any biological fluid of interest such as dermal fluid, interstitial fluid, plasma, blood, lymph, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage, amniotic fluid, or the like. In particular embodiments, analyte sensors of the present disclosure may be adapted for assaying dermal fluid or interstitial fluid to determine analyte concentrations in vivo. It is to be appreciated, however, that the entirety of sensor control device 102 may have one or more various configurations permitting full transplantation beneath tissue and into one or more body fluids for assaying one or more analytes of interest, without departing from the scope of the present disclosure.

[0041] Referring again to FIG. 1, sensor 104 may automatically forward data to reader device 120. For example, analyte concentration data may be communicated automatically and periodically, such as at a certain frequency as data is obtained or after a certain time period has passed, with the data being stored in a memory until transmittal (e.g., every minute, five minutes, or other predetermined time period), such as by BLUETOOTH® or BLUETOOTH® Low Energy protocols. Data associated with different analytes may be forwarded at the same frequency or different frequencies and / or using the same or different communication protocols. In other embodiments, sensor 104 may communicate with reader device 120 in a non-automatic manner and not according to a set schedule. For example, data may be communicated from sensor 104 using RFID technology when the sensor electronics are brought into communication range of reader device 120. Until communicated to reader device 120, data may remain stored in a memory of sensor 104. Thus, a user does not have to maintain close proximity to reader device 120 at all times, and can instead upload data at a convenient time, automatically or non-automatically. In yet other embodiments, a combination of automatic and non-automatic data transfer may be implemented. For example, data transfer may continue on an automatic basis until reader device 120 is no longer in communication range of sensor 104.

[0042] An introducer may be present transiently to promote introduction of sensor 104 into a tissue. In illustrative embodiments, the introducer may comprise a needle or similar sharp, or a combination thereof. It is to be recognized that other types of introducers, such as sheaths or blades, may be present in alternative embodiments. More specifically, the needle or other introducer may transiently reside in proximity to sensor 104 prior to tissue insertion and then be withdrawn afterward. While present, the needle or other introducer may facilitate insertion of sensor 104 into a tissue by opening an access pathway for sensor 104 to follow. For example, the needle may facilitate penetration of the epidermis as an access pathway to the dermis to allow implantation of sensor 104 to take place, according to one or more embodiments. After opening the access pathway, the needle or other introducer may be withdrawn so that it does not represent a sharps hazard. In illustrative embodiments, suitable needles may be solid or hollow, beveled or non-beveled, and / or circular or noncircular in cross-section. In more particular embodiments, suitable needles may be comparable in cross-sectional diameter and / or tip design to an acupuncture needle, which may have a cross-sectional diameter of about 250 microns. It is to be recognized, however, that suitable needles may have a larger or smaller cross-sectional diameter if needed for particular applications. For example, needles having a cross-sectional diameter ranging from about 300 microns to about 400 microns may be used.

[0043] In some embodiments, a tip of the needle (while present) may be angled over the terminus of sensor 104, such that the needle penetrates a tissue first and opens an access pathway for sensor 104. In other illustrative embodiments, sensor 104 may reside within a lumen or groove of the needle, with the needle similarly opening an access pathway for sensor 104. In either case, the needle may be subsequently withdrawn after facilitating sensor insertion.

[0044] Sensor configurations featuring a single active area that is configured for detection of a corresponding single analyte may employ two-electrode or three-electrode detection motifs. FIG. 2 shows a diagram of an analyte sensor having a three-electrodes disposed on a single layer and is further discussed herein. Each active area may be overcoated with a mass transport limiting membrane of the same or different composition.

[0045] When a single working electrode is present in an analyte sensor, three-electrode sensor configurations can comprise a working electrode, a counter electrode, and a reference electrode. Related two-electrode sensor configurations may comprise a working electrode and a second electrode, in which the second electrode may function as both a counter electrode and a reference electrode (z.e., a counter / reference electrode). The various electrodes can be laterally spaced apart from one another upon the sensor tail. In any of the sensor configurations disclosed herein, the various electrodes may be electrically isolated from one another by at least one barrier or similar insulator.

[0046] Analyte sensors featuring multiple working electrodes may similarly comprise at least one additional electrode. When one additional electrode is present, the one additional electrode may function as a counter / reference electrode for each of the multiple working electrodes. When two additional electrodes are present, one of the additional electrodes may function as a counter electrode for each of the multiple working electrodes and the other of the additional electrodes may function as a reference electrode for each of the multiple working electrodes. Further details on analyte sensor structures and functionality are described in U.S. Patent Publication No. 2021 / 0386339, which is incorporated by reference in its entirety.

[0047] As mentioned above, the electrodes can be disposed on a single surface. For purposes of example and not for limitation, FIG. 2 shows a diagram of an analyte sensor having three electrodes disposed on a single layer, such as a dielectric layer. As disposing multiple electrodes on a single substrate surface can increase interference between the electrodes, embodiments of the subject matter describe isolating the electrodes from each other to reduce such interference.

[0048] As provided herein and with reference to FIG. 2, the electrodes disposed on the single substrate surface can be electrically isolated from each other to reduce interference. Although FIG. 2 discloses three electrodes, embodiments of the disclosed subject matter further contemplate disposing two electrodes on a single substrate. For example, in embodiments having a working electrode and a reference electrode alone, these two electrodes can be electrically isolated from each other as discussed herein. In embodiments having a plurality of electrodes such as that contemplated by FIG. 2, the electrical isolation can be with respect to all three electrodes. The embodiment of FIG. 2 depicts three electrodes including a working electrode 214, a reference electrode 216, and a counter electrode 217.

[0049] According to embodiments of the disclosed subject matter, the overall thickness of the sensor can be reduced and more planar, resulting in a more uniform or approximately uniform membrane thickness along the sensor tail. By reducing the variability of the membrane depth across the sensor, the accuracy and sensitivity of sensor 200 can be improved. Additionally, minimizing the variability of the membrane thickness depth across the sensor can be beneficial during manufacturing and testing. For example, minimizing sensor thickness and having the electrodes all on one layer can help to prevent cumulative error and allows for more accurate deposition and measurement of the thickness during the manufacturing process, thus allowing for more accurate analyte sensitivity inferences based on the manufacturing measurements. As measurements of the membrane thickness (and its degradation thereof) in vivo can indicate the sensor sensitivity to analytes such as glucose, indicate signs of whether a sensor is functioning properly, or even indicate signs of whether the sensor was inserted correctly, having an accurate base measurement of the sensor thickness and its membrane provides for more accurate calculations and adjustments for tolerances. Embodiments of the disclosed subject matter such as having the electrodes all on one layer amongst other things contribute to the accuracy of the sensor, thus resulting in better sensitivity predictions. Maintaining a uniform thickness of the sensor with the membrane as manufactured helps to maintain a similar rate of use and degradation of the active components during use. Given that the depth of sensor insertion and physiological conditions at a given insertion depth can be inherently variable, sensing capability independent of sensor depth can provide fewer sources of error in predicting sensitivity and monitoring device stability when in use.

[0050] The membrane coating applied to substrate 212 can build up a cumulative thickness profile. With each small change in topology at the substrate 212, the topological variation in the resulting coating surface following deposition of each coating layer is magnified. By having an initial, minimally featured substrate 212 and disposed electrodes thereon according to the disclosed subject matter, a final membrane thickness with minimal variation can be realized.

[0051] To further interference reduction, an electrically isolating barrier can be disposed between electrodes on the single layer. As shown in FIG. 2, an electrically isolating barrier 232 is disposed between the working electrode 214, the reference electrode 216, and the counter electrode 217, which are disposed transversely adjacent each other on the single substrate surface 212. In examples having a two-electrode structure, a barrier 232 can be disposed between the working electrode 214 and the reference electrode 216. In embodiments including three electrodes or more, a barrier 232 can be disposed between each electrode, such as with respect to the example of FIG. 2.

[0052] Regardless of the number of electrodes used for the sensor, the sensor 200 can generally have a similar physical structure and footprint. For example, the substrate 212 can have a distal portion 234 and a proximal portion 236. The electrodes 214, 216, 217 can each have a head 238 disposed on the proximal portion 236 of the substrate 212, which are configured to connect to electronics components disposed within the sensor housing 103. The electrodes 214, 216, 217 can further include a conductive path 240 connected to the head 238. The path 240 can extend along a length of the substrate 212 to the distal portion 236 of the substrate 212. As shown in FIG. 2, the conductive paths 240 can terminate in their respective active areas 218.

[0053] The proximal portion 236 can have a wider dimension than the distal portion 234 such that the heads 238 can be spaced further apart than the conductive paths 240 to improve isolation. Such a structure can accommodate the limited area in the sensor housing 103 and the electronic components. Additionally, the barrier 232 can be made of several subbarriers. For example, in a two-electrode configuration, the barrier 232 can include a first barrier 232a abutting a portion of conductive path 240 of working electrode 214, as well as a second barrier 232b abutting conductive path 240 of reference electrode 216. In a three- electrode configuration, the counter electrode 217 can also include a third barrier 232c abutting its conductive path 240. Depending on whether the working electrode 214 or the reference electrode 216 is adjacent counter electrode 217, said adjacent electrode (i.e., either the working electrode 214 or the reference electrode 216) can have a fourth barrier 232d disposed along its conductive path adjacent counter electrode 217. Regardless of whether two or more electrodes are utilized, the barriers 232a-232b - and optionally 232c-232d - can run the length of their respective conductive paths 240.

[0054] As described with reference to the structure of the sensor herein, a method of producing an analyte sensor system is described. In particular, the method includes providing a substrate having a planar surface; disposing at least one barrier on the planar surface; disposing, on the planar surface of the substrate, a working electrode thereon and disposing an analyte-responsive enzyme on an active area of the working electrode; and disposing, on the planar surface of the substrate, a reference electrode thereon, wherein the at least one barrier is disposed between the working electrode and the reference electrode and configured to electrically isolate the working electrode from the reference electrode. In other embodiments, a method of producing an analyte sensor system is provided comprising: providing a substrate having a surface; disposing, on the surface, a layer having an analyte-responsive enzyme; removing at least a portion of the layer to create at least one barrier, wherein the at least one barrier electrically isolates a working electrode of the substrate from a reference electrode of the substrate, wherein the working electrode has an active area with the analyte-responsive enzyme thereon.

[0055] The method of disposing the barriers on the substrate is described herein. For example, the barriers 232a-232d can include jetted carbon ink barriers that are first disposed on the substrate prior to the printing of the electrodes. The use of jetted ink carbon barriers can isolate and visually obscure the electrode structure without affecting the electrode performance. Once the barriers are printed on the substrate, the electrodes can be printed - for example but not limitation, using screen printing - on the substrate at the appropriate locations. The barriers can provide the limiting structure to assist containing the printed electrodes from bleeding beyond the location of the barriers. Therefore, the barriers can be configured such their respective widths do not overlap each other and do not overlap with the withs of adjacent electrodes. In some embodiments, the jetted ink printing can bleed beyond the borders of the intended printed area of the barriers. Thus, the borders of the printed area can undergo any form of subtractive manufacturing to remove excess ink, as further described herein with reference to FIG. 5. For example and not limitation, the borders can be mechanically planed, laser planed, laser ablated, tamped, or chemically eroded or dilated. Additionally or alternatively, the barriers can include or be coated with either or both of a repellent material and a carbon-eroding acid, a carbon-modifying acid, or an insulating material. Additionally or alternatively, the barriers can be ablated to form an ablated zone, as discussed below.

[0056] To further improve the electrical isolation of the various electrodes 214, 216, 217, the surface between the electrodes 214, 216, 217 can be removed from the substrate via any form of subtractive manufacturing. For example and not limitation, the surface removal can be achieved via mechanical planing, laser planing, laser ablation, tamping, or chemical erosion or dilation. As shown in FIG. 2, the active areas 218 of electrodes 214, 216, and 217 can be further isolated by a fifth barrier 232e to create three different regions for sensing. The fifth barrier 232e can undergo any of the subtractive manufacturing processes described herein. An additional structure (not shown) can transversely overlay the fifth barrier to provide further electrical isolation amongst the three different regions for sensing. In some embodiments, the use of laser ablation techniques can result in the barrier having an ablated zone.

[0057] In other embodiments, a method of producing an analyte sensor system is provided such that the at least one barrier can be formed by removing at least a portion of a layer of the substrate in lieu of the jetted ink barrier. In particular, a method of producing an analyte sensor system is disclosed comprising: providing a substrate having a surface; disposing, on the surface, a layer having an analyte-responsive enzyme; removing at least a portion of the layer to create at least one barrier, wherein the at least one barrier electrically isolates a working electrode of the substrate from a reference electrode of the substrate, wherein the working electrode has an active area with the analyte-responsive enzyme thereon.

[0058] In contrast to the disclosed subject matter, FIG. 3 (prior art) shows an illustrative configuration for sensor 203 having a single working electrode 214 with two different active areas 218a / b disposed thereon and disposed on a single substrate 212. A reference electrode 216 is be disposed on an opposite side of the substrate 212 as the reference electrode. Such configuration increases the total thickness of the sensor in addition to increasing the thickness of the membrane 220, disposed on two sides of the substrate 212.

[0059] In further contrast to the disclosed subject matter, FIG. 4 (prior art) shows a cross- sectional diagram of an illustrative analyte sensor configuration having two working electrodes, a reference electrode, and a counter electrode. As shown, analyte sensor 400 includes working electrodes 404 and 406 disposed upon opposite faces of substrate 402, which increases the width of the sensor. First active area 410a is disposed upon the surface of working electrode 404, and second active area 410b is disposed upon the surface of working electrode 406. Counter electrode 420 is electrically isolated from working electrode 404 by dielectric layer 422, and reference electrode 431 is electrically isolated from working electrode 406 by dielectric layer 423, which further increase the width of the sensor. Outer dielectric layers 430 and 432 are positioned upon reference electrode 431 and counter electrode 420, respectively. Membrane 440 may overcoat at least active areas 410a and 410b with other components of analyte sensor 400 or the entirety of analyte sensor 400 optionally being overcoated with membrane 440 as well. As shown, the membrane 440 is disposed at varying depths with respect to the different layers of the sensor, which can effect the sensitivity of the sensor and degrade components of the sensor at varying rates as discussed above with respect to conventional configurations. The disclosed subject matter overcomes such deficiencies.

[0060] A carbon working electrode may suitably comprise the working electrode(s) in any of the analyte sensors disclosed herein. While carbon working electrodes are very commonly employed in electrochemical detection, use thereof in electrochemical sensing is not without difficulties. In particular, current related to an analyte of interest only results when an active area interacts with an analyte and transfers electrons to the portion of the carbon working electrode adjacent to the active area. Bodily fluid containing an analyte of interest also interacts with a carbon surface of the carbon working electrode not overcoated with an active area and does not contribute to the analyte signal, since there is no enzyme or enzyme system present at these locations to facilitate electron transfer from the analyte to the working electrode. Interferents may, however, undergo oxidation at portions of the working electrode lacking an active area and contribute background to the overall signal. Thus, carbon working electrodes with an extraneous (or “exposed”) carbon area upon the electrode surface do not meaningfully contribute to the analyte signal and may lead to contributory background signals in some cases. Other electrodes having an excessive surface area not directly detecting an analyte of interest may experience similar background signals and may be enhanced through modification of the disclosure herein.

[0061] FIG. 5 shows an image of electron microscopy of a working electrode 214 and a reference electrode 216 separated by a barrier 232. As depicted, the working electrode 214 has active chemistry and is separated from the reference electrode 216 by the barrier 232. As described above, the barrier can include j etted carbon ink barriers 232a / 232b that are disposed and printed on the substrate as provided by FIG. 5. In the image of FIG. 5, the surface area separating the working electrode 214 and the reference electrode 216 has further been laser ablated along the paths 232e to remove excess ink and to provide a non- conductive region, which further isolates and separates the working electrode 214 from the reference electrode 216. Adjacent the reference electrode 216 is an edge of the sensor tail as shown in FIG. 5.

[0062] FIG. 6 shows an image of light microscopy of an analyte sensor during manufacturing having printed barriers 232a / 232b. In some embodiments, and as shown in FIG. 6, the distance between the individual barriers can range such as between 20pm and 50pm, and more particularly 30pm and 35pm. Furthermore, a width of the individual barriers can range such as between 15pm and 30pm, and more particularly 20pm and 25pm. Additionally, in some embodiments, the individual barriers can have a height from the planar surface of substrate 212 which is greater than a height of each working electrode 214, 216, 217 from the planar surface of the substrate 212. Particularly, the height of the barrier from the substrate 212 can be between 5 pm and 50 pm.

[0063] Although various interferents may interact with the working electrode of the analyte sensors described herein, ascorbic acid is one example of an interferent commonly present in biological fluids that may generate a background signal at a carbon working electrode. For example, ascorbic acid oxidizes at the working electrode to produce dehydroascorbic acid. Various embodiments of the present disclosure will be described herein with reference to the interferent being ascorbic acid; however, it is to be understood that the embodiments and analyte sensor configurations described herein are equally applicable to other interferents (electroactive species within a bodily fluid having an analyte of interest).

[0064] Embodiments disclosed herein include:

[0065] A. An analyte sensor system comprising: a substrate having a planar surface; a working electrode disposed on the planar surface of the substrate and comprising an active area, the active area having an analyte-responsive enzyme; a reference electrode disposed on the planar surface of the substrate at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode; and at least one barrier disposed in the region between the working electrode and the reference electrode, wherein the at least one barrier includes an ablated zone, the at least one barrier configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the planar surface of the substrate.

[0066] B. A method of producing an analyte sensor system comprising: A method of producing an analyte sensor system comprising: providing a substrate having a planar surface; printing at least one barrier on the planar surface; disposing, on the planar surface of the substrate, a working electrode thereon and disposing an analyte-responsive enzyme on an active area of the working electrode; and disposing, on the planar surface of the substrate, a reference electrode thereon at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode; and wherein the at least one barrier is disposed in the region between the working electrode and the reference electrode, the at least one barrier is configured to electrically isolate the working electrode from the reference electrode.

[0067] C. A method of producing an analyte sensor system comprising: providing a substrate; disposing a layer on a portion of the substrate; disposing, on the layer, an analyte- responsive enzyme; removing at least a portion of the substrate and layer to create at least one barrier, a working electrode, and a reference electrode, wherein the at least one barrier electrically isolates the working electrode from a reference electrode , wherein the working electrode has an active area with the analyte-responsive enzyme thereon.

[0068] D. An analyte sensor system comprising: a substrate having a planar surface; a working electrode disposed on the planar surface of the substrate and comprising an active area, the active area having an analyte-responsive enzyme; a reference electrode disposed on the planar surface of the substrate at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode; and at least one barrier disposed in the region between the working electrode and the reference electrode and abutting at least one of the working electrode and the reference electrode, wherein each of the at least one barrier, working electrode, and reference electrode have a respective width, wherein the width of the at least one barrier does not overlap with the width of either the working electrode or the reference electrode, the at least one barrier configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the planar surface of the substrate.

[0069] Embodiment A may have one or more of the following additional elements in any combination: Element Al : wherein the at least one barrier further comprises at least one of a jetted ink barrier disposed on the region or a laser ablated barrier formed from the planar surface of the region.

[0070] Element A2: wherein the substrate comprises a distal portion and a proximal portion, wherein the at least one barrier along the distal portion comprises the laser ablated barrier and the at least one barrier along the proximal portion comprises the jetted ink barrier.

[0071] Element A3 : wherein the substrate comprises a distal portion and a proximal portion, wherein the at least one barrier along the distal portion comprises the jetted ink barrier and the at least one barrier along the proximal portion comprises the laser ablated barrier.

[0072] Element A4: wherein the substrate comprises a distal portion and a proximal portion, wherein the at least one barrier along the distal portion comprises at least one of the jetted ink barrier or the laser ablated barrier and the at least one barrier along the proximal portion is at least one of the jetted ink barrier or the laser ablated barrier.

[0073] Element A5: wherein the at least one barrier further comprises the jetted ink barrier disposed on the region.

[0074] Element A6: wherein a portion of the jetted ink barrier is ablated.

[0075] Element A7: wherein the at least one barrier abuts at least one of the working electrode or the reference electrode along a single side thereof.

[0076] Element A8: wherein the at least one barrier has a height dimension from the planar surface greater than a height dimension from the planar surface of either the working electrode or the reference electrode.

[0077] Element A9: wherein the height dimension of the at least one barrier ranges between 5 pm and 50 pm. Optionally, the height dimension of the at least one barrier is greater than 5 pm. Optionally, the height dimension is less than 50 pm.

[0078] Element A10: wherein each of the at least one barrier, working electrode, and reference electrode respectively have a width, wherein the width of the at least one barrier does not overlap with the width of either the working electrode or the reference electrode.

[0079] Element Al l : wherein the substrate comprises a distal portion and a proximal portion; the working electrode comprises a first conductive path disposed on the distal portion of the substrate and a first head disposed on the proximal portion of the substrate; the reference electrode comprises a second conductive path disposed on the distal portion of the substrate and disposed at a first distance to the first conductive path, and a second head disposed on the proximal portion of the substrate and disposed at a second distance to the second head; wherein the at least one barrier comprises a first barrier and a second barrier, the first barrier abuts the first conductive path and the second barrier abuts the second conductive path.

[0080] Element A12: wherein the at least one barrier comprises a first barrier and a second barrier, the first conductive path comprises a first conductive path length and the first barrier abuts the first conductive path; the second conductive path comprises a second conductive path length and the second barrier abuts the second conductive path; the first barrier comprises a first barrier length approximately equal to the first conductive path length; and the second barrier comprises a second barrier length approximately equal to the second conductive path length.

[0081] Element A13: further comprising a counter electrode disposed on the planar surface of the substrate and electrically isolated from each of the working electrode and the reference electrode on the planar surface of the substrate.

[0082] Element A14: wherein the counter electrode comprises a third conductive path disposed on the distal portion of the substrate and a third head disposed on the proximal portion of the substrate; and the at least one barrier further comprises a third barrier abutting the third conductive path.

[0083] Element Al 5: wherein the third conductive path comprises a third conductive path length and the third barrier comprises a third barrier length approximately equal to the third conductive path length.

[0084] Element A16: wherein the at least one barrier further comprises a fourth barrier abutting one of the first conductive path and the second conductive path, the fourth barrier having a fourth barrier length approximately equal to the first conductive path length or the second conductive path length, respectively.

[0085] Element Al 7: wherein a distance between the first barrier and the second barrier ranges between 20pm and 50pm.

[0086] Element A18: wherein a width of the first barrier ranges between 15pm and 30pm and a width of the second barrier ranges between 15pm and 30pm. Optionally, the width of the first or second barrier is greater than 15 pm. Optionally, the width of the first or second barrier is less than 30pm.

[0087] Element A19: wherein the ablated zone is at least a portion of the region located between the first barrier and the second barrier.

[0088] Element A20: wherein the ablated zone is at least a portion of the region located between the third barrier and the fourth barrier. Element A21 : wherein the at least one barrier includes a fifth barrier, wherein the fifth barrier extends from a first portion of the region located between the first barrier and the second barrier to a second portion of the region located between the third barrier and the fourth barrier.

[0089] Element A22: wherein the at least one barrier comprises at least one of a repellent surface or a carbon-eroding acid.

[0090] Element A23: wherein the reference electrode is a counter electrode.

[0091] Element A24: further comprising a membrane disposed over the substrate configured to control a rate of transfer of an analyte therethrough.

[0092] Element A25: wherein the membrane includes a uniform thickness dimension.

[0093] By way of non-limiting example, exemplary combinations applicable to A include, but are not limited to: A with any one or more or all of A1-A25, in any combination.

[0094] Embodiment B may have one or more of the following additional elements in any combination:

[0095] Element Bl : further comprising ablating a zone of the at least one barrier to define an ablated zone.

[0096] Element B2: wherein the substrate comprises a distal portion and a proximal portion, the working electrode comprises a first conductive path and a first head and the reference electrode comprises a second conductive path and a second head, the at least one barrier comprises a first barrier and a second barrier, and the method further comprises: disposing the first conductive path on the distal portion of the substrate and disposing the first head on the proximal portion of the substrate; and disposing the second conductive path on the distal portion of the substrate at a first distance to the first conductive path and disposing the second head on the proximal portion of the substrate at a second distance to the first head, wherein the first barrier abuts the first conductive path; and the second barrier abuts the second conductive path.

[0097] Element B3: further comprising: disposing, on the planar surface of the substrate, a counter electrode thereon; and electrically isolating the counter electrode from each of the working electrode and the reference electrode with the at least one barrier.

[0098] Element B4: wherein the first barrier is disposed from the second barrier at a distance ranging between 20pm and 50pm. Optionally, the distance between the first barrier and the second barrier is greater than 20pm. Optionally, the distance between the first barrier and the second barrier is less than 50pm. Element B5: wherein the first barrier is disposed onto the planar surface at a width dimension ranging range between 15pm and 30pm and the second barrier is disposed onto the planar surface at a width dimension ranging between 15pm and 30pm. Optionally, the width of the first or second barrier is greater than 15 pm. Optionally, the width of the first or second barrier is less than 30pm.

[0099] Element B6: wherein the ablating is laser ablating.

[0100] Element B7: wherein a side of the at least the working electrode or the reference electrode is disposed so as to abut the at least one barrier.

[0101] Element B8: wherein the at least one barrier has a height dimension from the planar surface greater than a height dimension from the planar surface of either the working electrode or the reference electrode.

[0102] Element B9: wherein each of the at least one barrier, working electrode, and reference electrode respectively have a width, wherein the method further comprises preventing the width of either the working electrode or the reference electrode from overlapping with the width of the at least one barrier.

[0103] Element BIO: wherein disposing at least one barrier on the planar surface further comprises jet-ink printing the at least one barrier on the planar surface.

[0104] Element Bl 1 : further comprising disposing at least one of a repellent surface on the at least one barrier or a carbon-eroding acid on the at least one barrier.

[0105] Element B 12: further comprising disposing a membrane over the substrate, wherein the membrane is configured to control a rate of transfer of an analyte therethrough.

[0106] Element B 13: wherein disposing the membrane over the substrate includes disposing at least one layer of the membrane at a uniform thickness dimension.

[0107] By way of non-limiting example, exemplary combinations applicable to B include, but are not limited to: B with any one or more or all of B1-B13, in any combination.

[0108] Embodiment C may have one or more of the following additional elements in any combination:

[0109] Element Cl : wherein the substrate comprises a distal portion and a proximal portion and the removing at least a portion of the substrate comprises: forming a first conductive path of the working electrode on the distal portion of the substrate and forming a first head of the working electrode on the proximal portion of the substrate, and forming a second conductive path of the reference electrode on the distal portion of the substrate and forming a second head of the reference electrode on the proximal portion of the substrate, wherein the at least one barrier separates the first conductive path and the first head from the second conductive path and the second head.

[0110] Element C2: wherein the first conductive path is disposed at a first distance to the second conductive path and wherein the first head is disposed at a second distance to the second head.

[0111] Element C3: wherein the first distance ranges between 20pm and 50pm away from the second conductive path. Optionally wherein the first distance is greater than 20pm. Optionally wherein the first distance is less than 50pm.

[0112] Element C4: wherein the removing at least a portion of the substrate further comprises: forming a counter electrode from a remaining portion of the substrate.

[0113] Element C5: wherein removing at least a portion of the substrate comprises ablating the layer and substrate.

[0114] Element C6: wherein the ablating is laser ablating.

[0115] Element C7: further comprising disposing at least one of a repellent or a carbon- eroding acid on the at least one barrier.

[0116] Element C8: further comprising disposing a membrane over the substrate and layer, wherein the membrane is configured to control a rate of transfer of an analyte therethrough.

[0117] By way of non-limiting example, exemplary combinations applicable to C include, but are not limited to: C with any one or more or all of C1-C8, in any combination.

[0118] Embodiment D may have one or more of the following additional elements in any combination:

[0119] Element DI : wherein the at least one barrier further comprises at least one of a jetted ink barrier disposed on the region or a laser ablated barrier formed from the planar surface of the region; the substrate comprises a distal portion and a proximal portion; the working electrode comprises a first conductive path disposed on the distal portion of the substrate and a first head disposed on the proximal portion of the substrate; the reference electrode comprises a second conductive path disposed on the distal portion of the substrate and disposed at a first distance to the first conductive path, and a second head disposed on the proximal portion of the substrate and disposed at a second distance to the second head; and the at least one barrier comprises a first barrier and a second barrier, the first barrier abuts the first conductive path and the second barrier abuts the second conductive path.

[0120] Element D2: wherein a distance between the first barrier and the second barrier ranges between 20pm and 50pm. Optionally, the distance between the first barrier and the second barrier is greater than 20pm. Optionally, the distance between the first barrier and the second barrier is less than 50pm.

[0121] By way of non-limiting example, exemplary combinations applicable to D include, but are not limited to: D with any one or more or all of D1-D2, in any combination.

[0122] To facilitate a better understanding of the embodiments described herein, the following examples of various representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention.

[0123] In summary, analyte sensors are being increasingly employed for monitoring various analytes in vivo. Analyte sensors may feature enhancements to address signals obtained from interferent species. Some analyte sensors may comprise a substrate having a planar surface, a working electrode disposed on the surface of the substrate and comprising an active area, the active area having an analyte-responsive enzyme, a reference electrode disposed on the surface of the substrate and separated by a distance from the working electrode, and at least one barrier disposed between the working electrode and the reference electrode, wherein the barrier includes an ablated zone and is configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the surface of the substrate.

[0124] Unless otherwise indicated, all numbers expressing quantities and the like in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0125] One or more illustrative embodiments incorporating various features are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment incorporating the embodiments of the present invention, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in the art and having benefit of this disclosure.

[0126] While various systems, tools and methods are described herein in terms of “comprising” various components or steps, the systems, tools and methods can also “consist essentially of’ or “consist of’ the various components and steps.

[0127] As used herein, the phrase “at least one of’ preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of’ allows a meaning that includes at least one of any one of the items, and / or at least one of any combination of the items, and / or at least one of each of the items. By way of example, the phrases “at least one of A, B, C, and D” or “at least one of A, B, C, or D” each refer to only A, only B, or only

[0128] C, or only D; any combination of A, B, C, and D; and / or at least one of each of A, B, C, and

[0129] D.

[0130] Therefore, the disclosed systems, tools and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems, tools and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and / or any optional element disclosed herein. While systems, tools and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the systems, tools and methods can also “consist essentially of’ or “consist of’ the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the elements that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.

Claims

CLAIMSWhat is claimed is:

1. An analyte sensor system comprising: a substrate having a planar surface; a working electrode disposed on the planar surface of the substrate and comprising an active area, the active area having an analyte-responsive enzyme; a reference electrode disposed on the planar surface of the substrate at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode; and at least one barrier disposed in the region between the working electrode and the reference electrode, wherein the at least one barrier includes an ablated zone, the at least one barrier configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the planar surface of the substrate.

2. The analyte sensor system of claim 1, wherein the at least one barrier further comprises at least one of a jetted ink barrier disposed on the region or a laser ablated barrier formed from the planar surface of the region.

3. The analyte sensor system of claim 2, wherein the substrate comprises a distal portion and a proximal portion, wherein the at least one barrier along the distal portion comprises the laser ablated barrier and the at least one barrier along the proximal portion comprises the jetted ink barrier.

4. The analyte sensor system of claim 2, wherein the substrate comprises a distal portion and a proximal portion, wherein the at least one barrier along the distal portion comprises the jetted ink barrier and the at least one barrier along the proximal portion comprises the laser ablated barrier.

5. The analyte sensor system of claim 2, wherein the substrate comprises a distal portion and a proximal portion, wherein the at least one barrier along the distal portion comprises at least one of the jetted ink barrier or the laser ablated barrier and the at leastone barrier along the proximal portion is at least one of the jetted ink barrier or the laser ablated barrier.

6. The analyte sensor system of claim 2, wherein the at least one barrier further comprises the jetted ink barrier disposed on the region.

7. The analyte sensor system of claim 6, wherein a portion of the jetted ink barrier is ablated.

8. The analyte sensor system of claim 1, wherein the at least one barrier abuts at least one of the working electrode or the reference electrode along a single side thereof.

9. The analyte sensor system of claim 1, wherein the at least one barrier has a height dimension from the planar surface greater than a height dimension from the planar surface of either the working electrode or the reference electrode.

10. The analyte sensor system of claim 1, wherein the height dimension of the at least one barrier ranges between 5 pm and 50 pm.

11. The analyte sensor system of claim 1, wherein each of the at least one barrier, working electrode, and reference electrode respectively have a width, wherein the width of the at least one barrier does not overlap with the width of either the working electrode or the reference electrode.

12. The analyte sensor system of claim 2, wherein: the substrate comprises a distal portion and a proximal portion; the working electrode comprises a first conductive path disposed on the distal portion of the substrate and a first head disposed on the proximal portion of the substrate; the reference electrode comprises a second conductive path disposed on the distal portion of the substrate and disposed at a first distance to the first conductive path, and a second head disposed on the proximal portion of the substrate and disposed at a second distance to the second head;wherein the at least one barrier comprises a first barrier and a second barrier, the first barrier abuts the first conductive path and the second barrier abuts the second conductive path.

13. The analyte sensor system of claim 12, wherein: the at least one barrier comprises a first barrier and a second barrier, the first conductive path comprises a first conductive path length and the first barrier abuts the first conductive path; the second conductive path comprises a second conductive path length and the second barrier abuts the second conductive path; the first barrier comprises a first barrier length approximately equal to the first conductive path length; and the second barrier comprises a second barrier length approximately equal to the second conductive path length.

14. The analyte sensor system of claim 1, further comprising a counter electrode disposed on the planar surface of the substrate and electrically isolated from each of the working electrode and the reference electrode on the planar surface of the substrate.

15. The analyte sensor system of claim 14, wherein: the counter electrode comprises a third conductive path disposed on the distal portion of the substrate and a third head disposed on the proximal portion of the substrate; and the at least one barrier further comprises a third barrier abutting the third conductive path.

16. The analyte sensor system of claim 15, wherein the third conductive path comprises a third conductive path length and the third barrier comprises a third barrier length approximately equal to the third conductive path length.

17. The analyte sensor system of claim 15, wherein the at least one barrier further comprises a fourth barrier abutting one of the first conductive path and the secondconductive path, the fourth barrier having a fourth barrier length approximately equal to the first conductive path length or the second conductive path length, respectively.

18. The analyte sensor system of claim 12, wherein a distance between the first barrier and the second barrier ranges between 20pm and 50pm.

19. The analyte sensor system of claim 13, wherein a width of the first barrier ranges between 15pm and 30pm and a width of the second barrier ranges between 15pm and 30pm.

20. The analyte sensor system of claim 12, wherein the ablated zone is at least a portion of the region located between the first barrier and the second barrier.

21. The analyte sensor system of claim 17, wherein the ablated zone is at least a portion of the region located between the third barrier and the fourth barrier.

22. The analyte sensor system of claim 17, wherein the at least one barrier includes a fifth barrier, wherein the fifth barrier extends from a first portion of the region located between the first barrier and the second barrier to a second portion of the region located between the third barrier and the fourth barrier.

23. The analyte sensor system of claim 1, wherein the at least one barrier comprises at least one of a repellent surface or a carbon-eroding acid.

24. The analyte sensor system of claim 1, wherein the reference electrode is a counter electrode.

25. The analyte sensor system of claim 1, further comprising a membrane disposed over the substrate configured to control a rate of transfer of an analyte therethrough.

26. The analyte sensor system of claim 25, wherein the membrane includes a uniform thickness dimension.

27. A method of producing an analyte sensor system comprising: providing a substrate having a planar surface; printing at least one barrier on the planar surface; disposing, on the planar surface of the substrate, a working electrode thereon and disposing an analyte-responsive enzyme on an active area of the working electrode; and disposing, on the planar surface of the substrate, a reference electrode thereon at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode; and wherein the at least one barrier is disposed in the region between the working electrode and the reference electrode, the at least one barrier is configured to electrically isolate the working electrode from the reference electrode.

28. The method of claim 27, further comprising ablating a zone of the at least one barrier to define an ablated zone.

29. The method of claim 27, wherein the substrate comprises a distal portion and a proximal portion, the working electrode comprises a first conductive path and a first head and the reference electrode comprises a second conductive path and a second head, the at least one barrier comprises a first barrier and a second barrier, and the method further comprises: disposing the first conductive path on the distal portion of the substrate and disposing the first head on the proximal portion of the substrate; and disposing the second conductive path on the distal portion of the substrate at a first distance to the first conductive path and disposing the second head on the proximal portion of the substrate at a second distance to the first head, wherein the first barrier abuts the first conductive path; and the second barrier abuts the second conductive path.

30. The method of claim 27, further comprising: disposing, on the planar surface of the substrate, a counter electrode thereon; and electrically isolating the counter electrode from each of the working electrode and the reference electrode with the at least one barrier.

31. The method of claim 27, wherein the first barrier is disposed from the second barrier at a distance ranging between 20pm and 50pm.

32. The method of claim 27, wherein the first barrier is disposed onto the planar surface at a width dimension ranging range between 15pm and 30pm and the second barrier is disposed onto the planar surface at a width dimension ranging between 15pm and 30pm.

33. The method of claim 28, wherein the ablating is laser ablating.

34. The method of claim 27, wherein a side of the at least the working electrode or the reference electrode is disposed so as to abut the at least one barrier.

35. The method of claim 27, wherein the at least one barrier has a height dimension from the planar surface greater than a height dimension from the planar surface of either the working electrode or the reference electrode.

36. The method of claim 27, wherein each of the at least one barrier, working electrode, and reference electrode respectively have a width, wherein the method further comprises preventing the width of either the working electrode or the reference electrode from overlapping with the width of the at least one barrier.

37. The method of claim 27, wherein disposing at least one barrier on the planar surface further comprises jet-ink printing the at least one barrier on the planar surface.

38. The method of claim 27, further comprising disposing at least one of a repellent surface on the at least one barrier or a carbon-eroding acid on the at least one barrier.

39. The method of claim 27, further comprising disposing a membrane over the substrate, wherein the membrane is configured to control a rate of transfer of an analyte therethrough.

40. The method of claim 39, wherein disposing the membrane over the substrate includes disposing at least one layer of the membrane at a uniform thickness dimension.

41. A method of producing an analyte sensor system comprising: providing a substrate; disposing a layer on a portion of the substrate; disposing, on the layer, an analyte-responsive enzyme; removing at least a portion of the substrate and layer to create at least one barrier, a working electrode, and a reference electrode, wherein the at least one barrier electrically isolates the working electrode from a reference electrode , wherein the working electrode has an active area with the analyte-responsive enzyme thereon.

42. The method of claim 41, wherein the substrate comprises a distal portion and a proximal portion and the removing at least a portion of the substrate comprises: forming a first conductive path of the working electrode on the distal portion of the substrate and forming a first head of the working electrode on the proximal portion of the substrate, and forming a second conductive path of the reference electrode on the distal portion of the substrate and forming a second head of the reference electrode on the proximal portion of the substrate, wherein the at least one barrier separates the first conductive path and the first head from the second conductive path and the second head.

43. The method of claim 41, wherein the first conductive path is disposed at a first distance to the second conductive path and wherein the first head is disposed at a second distance to the second head.

44. The method of claim 41, wherein the first distance ranges between 20pm and 50pm away from the second conductive path.

45. The method of claim 41, wherein the removing at least a portion of the substrate further comprises:forming a counter electrode from a remaining portion of the substrate.

46. The method of claim 41, wherein removing at least a portion of the substrate comprises ablating the layer and substrate.

47. The method of claim 46, wherein the ablating is laser ablating.

48. The method of claim 41, further comprising disposing at least one of a repellent or a carbon-eroding acid on the at least one barrier.

49. The method of claim 41, further comprising disposing a membrane over the substrate and layer, wherein the membrane is configured to control a rate of transfer of an analyte therethrough.

50. An analyte sensor system comprising: a substrate having a planar surface; a working electrode disposed on the planar surface of the substrate and comprising an active area, the active area having an analyte-responsive enzyme; a reference electrode disposed on the planar surface of the substrate at a distance from the working electrode, wherein a region of the planar surface separates the reference electrode from the working electrode; and at least one barrier disposed in the region between the working electrode and the reference electrode and abutting at least one of the working electrode and the reference electrode, wherein each of the at least one barrier, working electrode, and reference electrode have a respective width, wherein the width of the at least one barrier does not overlap with the width of either the working electrode or the reference electrode, the at least one barrier configured to electrically isolate the working electrode from the reference electrode, and wherein the working electrode and the reference electrode are electrically isolated from each other on the planar surface of the substrate.

51. The analyte sensor system of claim 51, wherein:the at least one barrier further comprises at least one of a jetted ink barrier disposed on the region or a laser ablated barrier formed from the planar surface of the region; the substrate comprises a distal portion and a proximal portion; the working electrode comprises a first conductive path disposed on the distal portion of the substrate and a first head disposed on the proximal portion of the substrate; the reference electrode comprises a second conductive path disposed on the distal portion of the substrate and disposed at a first distance to the first conductive path, and a second head disposed on the proximal portion of the substrate and disposed at a second distance to the second head; and the at least one barrier comprises a first barrier and a second barrier, the first barrier abuts the first conductive path and the second barrier abuts the second conductive path.

52. The analyte sensor system of claim 51, wherein a distance between the first barrier and the second barrier ranges between 20pm and 50pm.

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