Analyte sensor morphology

Abstract

The invention relates to an analyte sensor for use in a medical device for measuring analyte data, in particular for measuring glucose data, in a fluid carrying an analyte, the analyte sensor comprising: a first electrode (101), which is a working electrode; a second electrode; a substrate (100) carrying the first electrode and the second electrode; at least one membrane (104) at least partially covering the first electrode (101), where the at least one membrane (101) comprises a membrane material impermeable to the analyte-bearing fluid and / or the analyte, where the at least one membrane comprises at least one opening (107), and wherein the at least one membrane (104) is configured for controlling the analyte-laden fluid and / or a flux of the analyte to the first electrode (101) via the at least one opening (107).

Description

Background Art

[0001] The present invention relates to an electrochemical analyte sensor for measuring analyte data, such as glucose data, in an analyte-carrying fluid.

[0002] Electrochemical analyte sensors utilize the fact that certain electrochemical reactions of the analyte to be detected or measured can generate electrical signals (eg, current or potential) that can be related to, eg, directly or indirectly proportional to, the concentration of the analyte to be detected.

[0003] For example, potentiometric electrochemical analyte sensors can generate potentials that can exhibit a logarithmic dependence on the concentration of the analyte to be detected.

[0004] For example, an amperometric electrochemical analyte sensor may generate a current that may flow between electrodes of the sensor, which current may be proportional to the concentration of the analyte to be measured.

[0005] Such analyte sensors are, for example, commonly used to measure glucose levels, and in particular may be part of an in vivo continuous glucose monitoring system that measures glucose levels in the blood and / or interstitial fluid of a patient suffering from diabetes.

[0006] However, current electrochemical analyte sensors suffer from a number of disadvantages. For example, the electrodes of current analyte sensors may exhibit significant material wear and may leak unwanted chemicals or materials into their environment.

[0007] Additionally, current electrochemical analyte sensors may suffer from slow response times and may exhibit non-linear measurement characteristics that can significantly reduce the accuracy, robustness, and reliability of analyte measurements.

[0008] Additionally, current electrochemical analyte sensors are rather complex and elaborate in structure and design and require complicated and expensive manufacturing steps.

[0009] Technical issues

[0010] It is therefore an object of the present invention to provide a device for obtaining more robust, more accurate and more reliable analyte measurements (eg, glucose measurements) using an electrochemical analyte sensor.

[0011] Another object of the present invention is to provide an improved electrochemical analyte sensor.

[0012] In particular, it is an object to provide a simplified, more compact, more cost-effective, more accurate and more reliable electrochemical analyte sensor.

[0013] Solution

[0014] According to the invention, at least one of said objects is achieved by the subject matter of the independent claims.

[0015] Advantageous embodiments and further developments are subject matter of the dependent claims.

[0016] Further advantageous embodiments and further developments are disclosed throughout the description.

[0017] For example, an electronic analyte sensor used in a medical device for measuring analyte data, particularly for measuring glucose data, in an analyte-carrying fluid may include one, some or all of the following components:

[0018] ● A first electrode, which is a working electrode

[0019] The second electrode,

[0020] a substrate (100) carrying the first electrode and the second electrode,

[0021] at least one membrane at least partially covering the first electrode,

[0022] wherein the at least one membrane comprises a membrane material that is impermeable to the analyte-carrying fluid and / or the analyte, wherein the at least one membrane comprises at least one opening, and wherein the at least one membrane is configured to control the flow of fluid to or toward the first electrode via the at least one opening

[0023] The flux of the analyte and / or the flux of the fluid carrying the analyte is controlled (particularly towards the electrochemically active layer of the first electrode).

[0024] At least one opening or multiple openings of at least one membrane provide a clearly defined flux channel for the flux of the analyte and / or the fluid carrying the analyte to the first electrode / working electrode (in particular to a portion of the working electrode including an electrochemical converter (e.g., an enzyme and / or a catalyst), i.e., to the electrochemically active layer of the working electrode).

[0025] The at least one membrane may also be referred to as a flux positioning membrane.

[0026] The working electrode may, for example, comprise a sensing material or a sensing layer as an electrochemically active layer configured to provide at least one enzyme to the first electrode / working electrode.

[0027] Exemplary properties of such sensing materials or sensing layers are further described below.

[0028] The at least one membrane may at least partially cover the first electrode and optionally also the second electrode.However, the at least one opening / openings of the at least one membrane may only be located in the portion of the membrane at least partially covering the first electrode.

[0029] Herein, the expression “covering” may also include the case where there are additional layers or components between at least one film and the first electrode and / or the second electrode, that is, the expression “covering” does not necessarily mean direct contact between at least one film and the first electrode and / or the second electrode.

[0030] The analyte sensor or electrochemical analyte sensor may be, for example, an amperometric analyte sensor or a coulometric analyte sensor.

[0031] Analyte sensors may be configured for use in medical devices, particularly for use in portable (eg, wearable / on-body) electronic medical devices that may measure analyte data and other medical data.

[0032] The substrate for carrying or supporting the first and second electrodes and other components of the analyte sensor may be a flat planar structure, and the substrate material may include polyester.

[0033] The first electrode and the second electrode of the analyte sensor can be arranged on opposite sides or surfaces of the substrate, for example, the top surface and the bottom surface. However, it is also conceivable that the first electrode and the second electrode are arranged on the same side or the same surface of the substrate in a coplanar manner.

[0034] In this context, an analyte-carrying fluid is to be understood to mean, in particular, a body fluid of a user, in particular a patient suffering from diabetes, such as blood and / or interstitial fluid.

[0035] The analyte sensor may further include at least one sensor circuit connected to the electrode and may be configured to operate and control the electrode and the analyte sensor operation. In addition, the analyte sensor may include a power source, such as a battery, which may provide power to the analyte sensor (particularly to the sensor circuit of the analyte sensor).

[0036] However, it is also contemplated that the analyte sensor may additionally or alternatively be configured to draw power from an electrochemical reaction occurring at the electrodes during use of the analyte sensor (ie, when the electrodes of the analyte sensor are in contact with a user's bodily fluid).

[0037] In this context, the membrane which is impermeable to the analyte or the analyte-carrying fluid may also refer to a component comprising one or more layers.

[0038] The membrane or membrane layer may further be understood to act as a selective barrier, in particular as a local selective barrier, which allows only specific particles / molecules / compounds / fluids / fluid components to pass through, while other particles / molecules / compounds / fluids / fluid components are blocked by the membrane, i.e. cannot diffuse through the membrane or can diffuse through the membrane only to a small / negligible extent.

[0039] In particular, the membrane material may be hydrophobic.

[0040] The film material can in particular also be an electrical insulator material or a semiconductor material.

[0041] The term impermeable membrane or impermeable membrane material may be specifically understood herein to refer to a membrane / membrane material that is substantially impermeable to specific particles, molecules, compounds, fluids or fluid components, i.e. the membrane or membrane material may be understood to have low permeability to specific particles, molecules, compounds, fluids or fluid components.

[0042] However, the term impermeable membrane or impermeable membrane material, in addition to referring to a membrane or membrane material that is completely (e.g., 100%) impermeable to an analyte or an analyte-carrying fluid, may also include situations where the membrane is impermeable or the membrane is only substantially impermeable (e.g., only blocks at least 60% or 80% or 90% or 99% of the analyte or the analyte-carrying fluid).

[0043] For example, the exemplary membrane comprising a membrane material that is impermeable to the analyte or the fluid carrying the analyte can be understood as a membrane comprising a membrane material whose effective diffusion coefficient for the fluid carrying the analyte is at least one or two orders of magnitude smaller than the diffusion coefficient of the membrane material that is permeable or completely permeable to the fluid carrying the analyte.

[0044] In other words, the at least one membrane or membrane material may provide analyte flux insulation, ie the at least one membrane may limit the flux of the analyte or the fluid carrying the analyte to components or layers beneath the membrane or membrane material.

[0045] For example, at least one membrane or membrane material may be configured such that at least 90%, preferably more, of the total flux of analyte or analyte-carrying fluid through the membrane is carried solely by openings in the membrane.

[0046] Other exemplary properties of membrane materials that are impermeable to the analyte or the analyte-carrying fluid are described further below.

[0047] As mentioned above, at least one membrane may comprise at least one opening, ie one or more openings or a plurality of openings.

[0048] An opening in this context may in particular be understood as a hole in or through the membrane, such as a through hole or a bore, a perforation and / or a slot or slit in the membrane, allowing one or more particles or molecules and / or compounds or fluid components to pass through the opening and through the membrane.

[0049] At least one opening may extend through or completely penetrate the membrane or membrane material.At least one opening may also extend through other layers below the membrane.

[0050] In particular, at least one opening allows at least one analyte to be measured (e.g., glucose) to pass through, and more particularly, allows an analyte-carrying fluid (e.g., body fluid) comprising at least one analyte to be measured to pass through to the electrochemically active layer or sensing layer of the working electrode and / or to other electrodes.

[0051] In other words, the at least one opening of the at least one membrane provides access for the analyte / analyte-carrying fluid to the electrochemically active layer or sensing layer of the working electrode. Exemplary properties of the electrochemically active layer or sensing layer or sensing material layer are further described below.

[0052] In other words, via at least one opening of the membrane or via multiple openings, the flux of the analyte-carrying fluid to the electrode of the analyte sensor can be controlled / regulated, for example the flux or flux transport of the analyte / analyte-carrying fluid to the working electrode or counter electrode of the analyte sensor.

[0053] In this document, the term or act of controlling or regulating the flux of an analyte or a fluid carrying an analyte may refer, in particular, to increasing and / or decreasing or limiting or positioning the flux of the analyte or the fluid carrying the analyte toward electrodes of an analyte sensor, such as toward a first electrode (e.g., a working electrode) and / or a second electrode (e.g., a counter electrode).

[0054] The at least one opening in the membrane may be generated or produced or formed, for example, by drilling, for example using a laser (eg by laser ablation) or using other drilling tools.

[0055] It may be preferred to use a laser ablation process to create or form the openings in the film as this may allow for better and more accurate control of properties such as the geometry and / or surface roughness of the openings in the film and their walls.

[0056] However, it is also conceivable to use self-organizing materials as film materials, such as copolymers of immiscible monomers that form the desired film morphology. It is also conceivable to use photoresist materials.

[0057] The structure of the analyte sensor described above and exemplarily herein provides many advantages. In particular, the improved control of the flux toward the electrode (e.g., toward the working electrode and / or toward the counter electrode) can, for example, prevent the occurrence of flux overload to the working electrode, i.e., can prevent the electrochemical converter (e.g., enzyme and / or catalyst) of the analyte sensor electrode from being overloaded.

[0058] The analyte sensor can thus be operated in an analyte flux control manner, i.e., in an analyte flux control regime. In other words, it is possible to avoid operating the analyte sensor in a regime that exhibits severe nonlinear measurement behavior, such as when the analyte sensor is operated in a kinetic (i.e., reaction) control regime.

[0059] Furthermore, this facilitates analyte transport or analyte flux to be the rate determining factor and thus the reaction current has a linear or substantially linear relationship with the concentration of the analyte to be measured. Thus, being able to operate in a flux transport controlled regime can improve the accuracy and reliability of analyte data measurements of the analyte sensor.

[0060] In addition, the structure of the analyte sensor exemplarily described above and in this article can ensure that the favorable linear measurement characteristics of the analyte sensor are maintained regardless of external factors such as temperature and humidity, and are also not affected by possible changes in enzyme activity at the working electrode (i.e., in / at the sensing layer of the working electrode), for example, due to aging.

[0061] The structures of the analyte sensors exemplarily described above and herein further allow sufficient or substantial amounts of electrochemical converters (eg, enzymes and / or catalysts) to always be available near / at the sensing layer of an electrode of the analyte sensor, eg, at a working electrode.

[0062] In this way, the local analyte flux density can be increased without leaving the global analyte flux transport control state.

[0063] Additionally, the at least one opening of the at least one membrane may provide a relatively high analyte flux throughput / analyte-carrying fluid flux throughput to an electrode (eg, a working electrode) of the analyte sensor.

[0064] Locally high analyte flux density may in particular ensure that the analyte sensor has a fast response time, for example in the order of tens of seconds or less.

[0065] In other words, the analyte sensors exemplarily described above and herein have advantageously linear measurement characteristics and advantageously fast response times compared to state of the art analyte sensors.

[0066] The shape / cross-section of the at least one opening may be circular, substantially circular, elliptical, polygonal, rectangular, square, regular, irregular, slit-like.

[0067] In the exemplary case of a membrane comprising a plurality of openings, the shape / cross-section of the openings in the plurality of openings may be the same, or each of the openings may have a different shape or cross-section, or subsets of the plurality of openings may have different shapes or different cross-sections between different subsets, i.e., the plurality of openings may be grouped into subsets of openings having the same or different shapes or cross-sections.

[0068] An exemplary diameter or average diameter of the opening / openings may be of similar size to the thickness of the at least one membrane and may be, for example, in the range of 10 to 100 microns.

[0069] For example, all openings may have similar or identical shapes and sizes.

[0070] Furthermore, the openings may be arranged on a regular grid with uniform density or on a random grid with uniform density.

[0071] The distance between adjacent or neighboring openings may be significantly greater, such as at least an order of magnitude greater than the thickness of the membrane or any other layer of the analyte sensor.

[0072] This further helps ensure that the analyte sensor is able to operate in an optimal linear analyte flux delivery control mode / state.

[0073] The more openings there are and the greater the separation of adjacent openings, the better the analyte flux localization and control, and the more robust the analyte sensor measurements.

[0074] The openings of at least one membrane (ie, a flux localizing membrane) described above and herein may provide a plurality of discrete, separate linear (eg, straight) flux channels through the membrane.

[0075] For example, adjacent flows of analytes or analyte-carrying fluids passing through the membrane via adjacent openings do not converge after having passed through the membrane, but instead exit the membrane as separate flows.

[0076] This behavior is particularly different from the behavior of fluid passing through the pores of a sponge-like structure, wherein fluid flows from different pores merge immediately before and / or after having passed through the pores of the sponge-like structure.

[0077] In other words, the opening of at least one membrane cannot / is not equivalent to a pore.

[0078] The opening of the at least one membrane is completely permeable to the analyte / analyte-carrying fluid and may be at least partially or completely filled with a material permeable to the analyte-carrying fluid, such as a hydrophilic polymer.

[0079] The filler material may be moderately to highly permeable / permeable to the analyte / analyte-carrying fluid.

[0080] For the sake of completeness, it should be noted that the filling material may also be air.

[0081] As previously described, the openings and the filling material of the openings may be configured such that at least 90%, preferably at least 99.9%, of the total analyte flux through the membrane passes through the openings in the membrane.

[0082] It is also possible that at least one membrane is embedded in the filling material that is permeable to the analyte / analyte-carrying fluid. In other words, the filling material can form a filling material layer or a diffusion limiting layer that allows controlling the diffusion of the analyte or the analyte-carrying fluid through the openings of the membrane (i.e., the flux positioning membrane).

[0083] The filling material or the diffusion limiting layer permeable to the analyte / analyte-carrying fluid may completely or at least partially cover the first electrode (101) and / or the second electrode.

[0084] Other characteristics of the fill material or diffusion limiting layer are described further below.

[0085] The structures of the analyte sensors exemplarily described above and herein can provide spatial modulation of analyte flux within or across the analyte sensor, wherein locally very high analyte flux density / flux rate can be achieved through the openings of the membrane (as well as above or below the openings), and negligible analyte flux or analyte flux rate can occur between or away from the openings.

[0086] The response time characteristics of the analyte sensor can then be given by the transmission characteristics of the opening alone (flux-weighted average) and can therefore be very fast compared to current sensors and response times of less than a few tens of seconds can be achieved.

[0087] The above-mentioned first electrode may be a working electrode, ie the at least one membrane may be configured to control the flux of the analyte / analyte-carrying fluid to the working electrode via the opening.

[0088] Exemplary properties of the sensing material / sensing layer of the working electrode

[0089] In order to achieve / generate and promote the electrochemical reaction of the analyte sensor with the analyte to be measured, the working electrode may include an electrochemical converter (eg, an enzyme) and / or a catalyst.

[0090] The analyte sensor may for example comprise a sensing material or a layer of sensing material or a sensing layer as an electrochemically active layer configured to provide at least one enzyme to the first electrode / working electrode. Said exemplary sensing layer may be located / arranged below / under the at least one membrane.

[0091] In particular, the first electrode / working electrode may comprise or may be covered by a sensing material or a sensing layer comprising at least one enzyme.

[0092] In other words, the sensing material or sensing layer may be part of the working electrode.

[0093] The first electrode / working electrode can include only one enzyme or a mixture of two or more enzymes. Only one enzyme is preferred. Specifically, the enzyme is capable of catalyzing a chemical reaction that converts an analyte, particularly glucose. Even more specifically, at least one enzyme is selected from the group consisting of glucose oxidase (EC 1.1.3.4), hexose oxidase (EC 1.1.3.5), (S)-2 hydroxy acid oxidase (EC 1.1.3.15), cholesterol oxidase (EC 1.1.3.6), glucose dehydrogenase, galactose oxidase (EC 1.1.3.9), alcohol oxidase (EC 1.1.3.13), L-glutamate oxidase (EC 1.4.3.11) and L-aspartate oxidase (EC 1.4.3.16). In particular, at least one enzyme is glucose oxidase (GOx) and / or its modification. In another preferred embodiment, at least one enzyme is glucose dehydrogenase, particularly FAD-dependent glucose dehydrogenase (FAD-GDH).

[0094] The at least one enzyme may be included in the exemplary sensing material or in the sensing layer covering the first electrode / working electrode. The sensing material or sensing layer may further include at least one polymer material; specifically, it may be or may include at least one polymer material and at least one metal-containing complex. The metal-containing complex may be selected from the group consisting of transition metal element complexes, specifically, the metal-containing complex may be selected from the following: osmium complexes, ruthenium complexes, vanadium complexes, cobalt complexes and iron complexes, such as ferrocene, such as 2-aminoethylferrocene. Even more specifically, the sensing material may be a polymeric transition metal complex as described in, for example, WO 01 / 36660A2, the contents of which are included by reference. In particular, the sensing material may include a modified poly(vinylpyridine) backbone loaded with a poly(bis-imino)Os complex covalently coupled via a bidentate bond. Suitable sensing materials are further described in Feldman et al., Diabetes Technology & Therapeutics, 5(5), 2003, 769-779, the contents of which are incorporated by reference. Suitable sensing materials may further include ferrocene-containing polyacrylamide-based viologen-modified redox polymers, pyrrole-2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-pyrene, naphthoquinone-LPEI. Polymeric transition metal complexes may represent redox mediators incorporated into cross-linked redox polymer networks.

[0095] This is advantageous because it can facilitate electron transfer between the at least one enzyme or analyte and the conductive traces connecting the working electrode to the sensor electronics.

[0096] To avoid or reduce undesirable elutriation or elution processes, redox mediators and enzymes can be covalently incorporated into the polymeric structure.

[0097] In an exemplary embodiment, the sensing material or sensing layer may include a polymeric material and MnO2 particles or any other material that catalyzes the oxidation reaction of hydrogen peroxide and at least one enzyme. Another possible material that catalyzes the oxidation reaction of hydrogen peroxide is Pt (platinum).

[0098] Furthermore, the sensing material may additionally comprise at least one cross-linking agent; the cross-linking agent may, for example, be capable of cross-linking at least a portion of the sensing material.

[0099] In addition, the first electrode / working electrode of the analyte sensor may include carbon / graphite and other sp 2 Hybridized carbon allotropes as conductive materials.

[0100] Exemplary sensing materials or sensing layers of the first electrode / working electrode may be located below the at least one membrane / below the at least one opening of the at least one membrane and may extend in particular over a large part or over the entire surface of the substrate on which the working electrode may be arranged.

[0101] In other words, the structure of the analyte sensor exemplarily described herein may be a multi-layer structure including a plurality of layers / structures / coatings.

[0102] For example, the portion of the analyte sensor including the first electrode (i.e., the working electrode) may be composed of the following layers, where the order is specified with reference to the external environment toward the interior of the analyte sensor, i.e., toward the substrate of the analyte sensor:

[0103] at least one membrane comprising a membrane material that is impermeable to the analyte-carrying fluid and / or the analyte, wherein the at least one membrane comprises at least one opening,

[0104] ● At least one sensing layer,

[0105] a first electrode configured as a working electrode,

[0106] - A substrate, wherein the substrate is configured to carry and / or support the components identified above.

[0107] At least one sensing layer may be part of a working electrode.

[0108] As previously mentioned, the opening of at least one membrane may be at least partially or completely filled with a material permeable to the analyte-carrying fluid, such as a hydrophilic polymer. The filling material may be used to control the flux density and / or diffusion of the analyte-carrying fluid / analyte through the opening of at least one membrane.

[0109] At least one membrane may be embedded in the filler material. In other words, at least one membrane may be located below / under a filler material layer (eg a hydrophilic polymer layer) that is permeable to the analyte-carrying fluid.

[0110] Therefore, the filling material may be understood as an additional layer in the structure described above by way of example, wherein the filling material layer may be arranged above at least one membrane and / or below at least one membrane and / or may be embedded in at least one membrane.

[0111] In other words, the filling material may form a layer arranged on top of any other possible layer present in the analyte sensor and / or the filling material may form a layer arranged between other layers on the analyte sensor. The filling material or filling material layer may also be referred to as a diffusion limiting layer or flux limiting layer because, as described above, it may be used to control the flux density and / or diffusion of the analyte-carrying fluid / analyte through the opening of the at least one membrane.

[0112] For the sake of completeness, it should also be noted that, although the analyte-carrying fluid, which may also be referred to as a solvent, may be hydrophobic, the analyte-carrying fluid may also be more susceptible to the diffusion-limiting layer, i.e., the analyte-carrying fluid may more easily pass through the diffusion-limiting layer. In contrast, the analyte, which may also be referred to as a solvate, may not be susceptible to the diffusion-limiting layer, and thus the diffusion-limiting layer may further control / limit the diffusion of the analyte through the openings of the at least one membrane.

[0113] Thus, the exemplary analyte sensors described herein may be configured such that below / under at least one membrane (having at least one opening) and below the layer of filling material may be a thin layer of sensing material / thin sensing layer, wherein the sensing layer may be part of a working electrode or may be a layer in direct contact with the working electrode.

[0114] In this context, a thin sensing layer is understood to mean a layer thickness in the range of a few micrometers, for example less than 5 μm.

[0115] Since the sensing layer is relatively thin, it can be ensured that a large / sufficient amount of electrochemical converters, such as enzymes and / or catalysts, are available near / at the first electrode / working electrode.

[0116] Furthermore, the sensing layer may have a permeability to the analyte or the analyte-carrying fluid which is at least as high as the permeability of the optional filling material of the openings, preferably higher / substantially higher than this permeability.

[0117] This may facilitate interaction of the analyte / analyte-carrying fluid with the sensing layer of or associated with the first electrode / working electrode.

[0118] For example, due to the high permeability of the sensing layer to the analyte / analyte-carrying fluid, the analyte / analyte-carrying fluid / analyte flux located at / below the opening can also reach parts / positions of the sensing layer / first electrode / working electrode that are away from / further away from the opening of the membrane.

[0119] This further facilitates the realization of analyte sensors that operate in a linear measurement regime in a reliable, accurate manner and with a fast response time.

[0120] For the sake of completeness, it should be noted that possible layers below or above the membrane may also include openings that align with the openings of the membrane. For example, the sensing layer and / or electrodes, such as the first electrode, such as the working electrode, and / or the second electrode, such as the counter electrode may have openings / may have openings that align with the openings in the membrane layer.

[0121] Furthermore, it should be noted that the optional exemplary filler material layer or diffusion limiting layer may have a thickness of a few micrometers, for example less than 5 μm.

[0122] The at least one membrane comprising a membrane material that is impermeable to the analyte-carrying fluid and / or the analyte may also have a thickness of a few micrometers, for example less than 5 μm, or even as low as one or a few nanometers.

[0123] The first electrode / working electrode may also have a diameter of several micrometers, for example less than 5 μm, or even as small as one or several nanometers.

[0124] In an alternative exemplary multilayer structural design of the portion of the analyte sensor including the first electrode (i.e., the working electrode), the layers may be structured as follows, with the order again specified with reference to the external environment toward the interior of the analyte sensor, i.e., toward the substrate of the analyte sensor:

[0125] A filler material layer having a material permeable to the analyte / analyte-carrying fluid, such as a hydrophilic polymer

[0126] a first electrode configured as a working electrode, wherein the first electrode comprises a material that is impermeable to the analyte and / or the analyte-carrying fluid and is configured to act as a local selective barrier to the analyte and / or the analyte-carrying fluid, wherein the first electrode / working electrode comprises at least one opening to allow the analyte / analyte-carrying fluid to pass through at least towards the sensing layer,

[0127] at least one sensing layer as part of or associated with the first electrode / working electrode,

[0128] - A substrate, wherein the substrate is configured to carry and / or support the components identified above.

[0129] In this exemplary alternative design, the first electrode / working electrode itself acts as a membrane, which includes a material that is impermeable to the analyte / analyte-carrying fluid and is configured to allow the analyte / analyte-carrying fluid to pass only through at least one opening of the first electrode / working electrode.

[0130] For example, the electrode material that is impermeable to the analyte / analyte-carrying fluid may comprise carbon.

[0131] Therefore, alternative designs of analyte sensors for use in medical devices for measuring analyte data, particularly for measuring glucose data, in an analyte-carrying fluid may include:

[0132] a first electrode, which is a working electrode, and

[0133] The second electrode,

[0134] a substrate carrying a first electrode and a second electrode,

[0135] wherein the first electrode comprises a material that is impermeable to the analyte-carrying fluid and / or impermeable to the analyte, and wherein the first electrode comprises at least one opening, and wherein the first electrode is configured to control a flux of the analyte-carrying fluid and / or the analyte to the electrochemically active layer of the first electrode via the at least one opening.

[0136] The electrochemically active or sensing layer of the first electrode may correspond to or be identical to the electrochemically active or sensing layer and its characteristics described with respect to the design comprising a flux localizing membrane.

[0137] As in the design comprising a flux localizing membrane having openings, this alternative design may also include a diffusion limiting layer / filling material layer that is permeable to the analyte / analyte-carrying fluid and may completely or at least partially fill the openings of the first electrode / working electrode.

[0138] Furthermore, the diffusion limiting layer / filling material layer may completely or at least partially cover the first electrode / working electrode and / or the second electrode / counter electrode.

[0139] In this example, the opening of the first electrode / working electrode may have the same characteristics, such as the same geometry and size as the opening of the at least one membrane comprising a membrane material that is impermeable to the analyte / analyte-carrying fluid.

[0140] To ensure possible alignment of possible openings in all possible designs of analyte sensors and across all or some possible different layers of the analyte sensor, the possible openings may be produced / generated / formed via the same process, for example via laser ablation or another drilling method.

[0141] The above-mentioned exemplary second electrode may be an electrode selected from the group consisting of: a counter electrode and a combined counter / reference electrode.

[0142] Unless expressly stated otherwise, a first electrode described herein may be referred to as a working electrode and a second electrode may be referred to as a counter electrode or a combined counter / reference electrode of the analyte sensors described herein.

[0143] Furthermore, the second electrode / counter electrode may be an oxygen electrode, which may be configured to use oxygen dissolved / dissolved in the analyte-carrying fluid / body fluid / interstitial fluid as an electron acceptor, and may include gold or platinum as a conductive material and catalyst.

[0144] Using oxygen dissolved in the analyte-carrying fluid as a renewable resource, the wear time of the second electrode / counter electrode may be increased / extended compared to state of the art counter electrodes.

[0145] In addition, the analyte sensor designs described herein allow for the elimination of the need for dedicated reference electrodes, particularly reference electrodes that are susceptible to undesirable material wear and may leak undesirable materials into their environment, such as Ag / AgCl (silver / silver chloride) reference electrodes. This can further increase the life of the analyte sensor, among other things.

[0146] The second electrode may be further configured to measure the oxygen saturation / oxygen saturation level / oxygen saturation concentration in its environment (ie in the analyte-carrying fluid / body fluid / interstitial fluid).

[0147] This optional measurement of oxygen saturation / oxygen saturation level / oxygen saturation concentration may be used to compensate for possible measurement errors of the analyte sensor, since the oxygen saturation / oxygen saturation level / oxygen saturation concentration may affect the electrochemical reaction used by the analyte sensor to measure the analyte concentration, particularly in the case of an oxidative electrochemical reaction.

[0148] The optional possibility to measure and output the oxygen saturation / oxygen saturation level / oxygen saturation concentration in a body fluid (eg blood) and / or interstitial fluid of the patient can also be used for further additional therapeutic and diagnostic purposes.

[0149] As exemplarily described above, the analyte sensor may include a substrate, wherein a first electrode (eg, a working electrode) and a second electrode (eg, a counter electrode) may be arranged / located on different sides / positions / locations / portions of a surface of the substrate.

[0150] The substrate may be a flat planar structure, wherein, for example, a first electrode / working electrode may be disposed on a top surface of the substrate and a second electrode / counter electrode may be disposed on a bottom surface of the substrate.

[0151] However, it is also conceivable that the electrodes may be arranged in a coplanar manner on the surface of the substrate at different locations on the same surface of the substrate / substrate layer.

[0152] Furthermore, the electrodes, ie, the first electrode / working electrode and the second electrode / counter electrode, may be planar electrodes in all variations and embodiments described herein.

[0153] In addition to the electrodes, the substrate may be further configured to carry any sensor circuit components connected / associated with the electrodes and other components of the analyte sensor, such as a power source that may provide power to the sensor circuit of the analyte sensor.

[0154] Thus, the multilayer structure of the analyte sensor exemplarily described above may include a substrate / substrate layer below / under the electrodes, such as under the first electrode / working electrode and / or the second electrode / counter electrode.

[0155] The exemplary design of the analyte sensor having electrodes disposed on opposite / different sides of the substrate, ie, surfaces of opposite substrates, may enable a more compact analyte sensor and more cost-effective manufacturing because conductive traces having both electrodes on the same side are not required.

[0156] For example, a first side of the substrate may be covered with conductive material of a first / working electrode, and a second side of the substrate may be covered with conductive material of a second / counter electrode, and further layers of material may then be applied if necessary.

[0157] The exemplary substrate / substrate layer that may house electrodes and sensor circuitry and other components of an analyte sensor may, for example, comprise polyethylene terephthalate (PET).

[0158] However, it is contemplated that other electrode designs may be implemented for analyte sensors, for example non-planar designs such as cylindrical / rod-shaped electrodes.

[0159] The at least one membrane may also be configured to control the flux of the analyte / analyte-carrying fluid to a second electrode (eg, a counter electrode).

[0160] In the exemplary case where the first electrode and the second electrode are arranged in a coplanar manner on different / opposite sides of the substrate / substrate layer, at least one film may be configured to cover both electrodes simultaneously.

[0161] Alternatively, the analyte sensor may include two membranes, a first membrane and a second membrane, wherein the first membrane is configured to cover a first electrode, such as a working electrode, and the second membrane is configured to cover a second electrode, such as a counter electrode.

[0162] Therein, the membrane may be applied to the first electrode (eg, working electrode) and / or the second electrode (eg, counter electrode), for example, by dip coating.

[0163] As previously mentioned, the analyte sensor may include at least one sensor circuit that includes / is connected to electrodes and may be configured to operate and control the operation of the analyte sensor and its electrodes.

[0164] As also previously mentioned, the analyte sensor may include a power source, such as a battery, which may provide power to the analyte sensor, and in particular to the sensor circuitry and / or electrodes of the analyte sensor.

[0165] In particular, the sensor circuit may further comprise at least one capacitor.

[0166] The possible exemplary capacitor may be used during operation of the analyte sensor to integrate the electrical signal / current flowing between the electrodes (ie, between the first / working electrode and the second / counter electrode of the analyte sensor).

[0167] The integration may then produce a voltage signal proportional to the capacitor charge, which may be used to determine analyte data and / or oxygen data in the analyte sensor environment (eg, in a bodily fluid).

[0168] For example, measuring the current I from enzymatic glucose conversion multiplied by a predetermined time increment Δt, ie integrating the current I over time, yields a charge Q stored on the capacitor that is proportional to the capacitor voltage V (at least for lower voltage levels).

[0169] Therefore, the following relationship

[0170] I*Δt=Q~V

[0171] It can be used to determine analyte data, such as glucose concentration, because the measured glucose current I, and therefore the glucose concentration, is proportional to the capacitor voltage increase over a given time interval.

[0172] Herein, the exemplary lower voltage level may refer to a voltage of less than 0.5V or less than 0.4V, and the exemplary current integration time may be based on the order of the sampling frequency of the analyte sensor, which may be every minute or every few minutes.

[0173] Data on oxygen levels and their diffusion flux can be obtained based on the Nernst equation, which can be expressed, for example, as

[0174]

[0175] , where E CE is the electrode potential of the counter electrode, and wherein the superscript 0 indicates the given standard conditions (i.e., temperature and pressure) of the standard oxygen electrode potential R is the universal gas constant, T is the temperature, z is the charge transfer number, F is the Faraday constant, and is the natural logarithm of the oxygen concentration in mol / 1

[0176] However, other variants of the Nernst equation can also be used which take into account, inter alia, partial pressures and activities which may modify the standard potential.

[0177] The temporal oscillation of the electrode voltage (i.e., the potential difference between the electrodes of the analyte sensor, i.e., the potential of the working electrode, E WE The potential E of the counter electrode CEThe potential difference between the electrodes (the potential difference between the electrodes) is controlled by the oxygen availability and therefore allows calculation of the dynamic oxygen flux. Thus, the total oxygen level can be obtained from the average (or maximum) electrode voltage.

[0178] The electrical signal / current flowing between the electrodes may thus be generated by applying a voltage signal between the first electrode and the second electrode of the analyte sensor by the sensor circuit of the analyte sensor.

[0179] Thus, an exemplary method for manufacturing the exemplary analyte sensor described above and herein for use in a medical device for measuring analyte data, particularly for measuring glucose data, in an analyte-carrying fluid may include one, some, or all of the following steps:

[0180] ●Will include a first electrode (eg, a working electrode) and a second electrode (eg, a counter electrode)

[0181] The sensor circuit is mounted to the substrate, wherein the first electrode and the second electrode may be mounted on different sides (e.g., opposite sides of the substrate, such as the top surface and the bottom surface sides)

[0182] or on the same side,

[0183] - Applying at least one membrane comprising a membrane material that is impermeable to the analyte-carrying fluid and at least partially or completely covering the first electrode and optionally the second electrode with the at least one membrane.

[0184] The sensing layer as further described above may be applied to the electrode, for example to the first electrode / to the working electrode, before or after mounting the sensor circuit and the electrodes on the substrate.

[0185] This step may be performed before applying the at least one film, such that the film may, for example, at least partially or completely cover the sensing layer and the underlying first / working electrode.

[0186] As mentioned before, it is also conceivable that the sensing layer is already part of the first electrode / working electrode and does not have to be applied to the first electrode / working electrode after it has been mounted to the substrate.

[0187] Before or after applying the at least one film, at least one opening may be formed / produced / created in the film.

[0188] For example, the at least one opening may be formed / produced / generated by a drilling and / or ablation process, such as by laser ablation.

[0189] After application of the at least one membrane, the at least one opening may be completely or at least partially filled with a (previously mentioned) material that is permeable to the analyte-carrying fluid, such as a hydrophilic polymer.

[0190] It is also possible that at least one membrane is embedded in said filling material, said filling material being permeable to the analyte-carrying fluid, and / or that a layer of said filling material is applied onto / on top of at least one membrane and at least one opening.

[0191] A filler material or a filler material layer or a diffusion limiting layer may also be applied to cover the second electrode / working electrode.

[0192] The step of applying a film or layer exemplarily described above can be carried out via dip coating.

[0193] The step of forming / producing / generating at least one opening may also be performed as a last step, ie after all other components and layers of the analyte sensor have been mounted on the substrate.

[0194] This may in particular allow forming at least one opening in at least one membrane at different depths on different layers / different materials of the analyte sensor.

[0195] For example, in the exemplary first type of at least one opening, the opening may be formed such that it penetrates / extends only through the at least one membrane and does not reach any possible other layers of the analyte sensor below the membrane.

[0196] In the exemplary second type of at least one opening, the opening may be formed such that it penetrates / extends through at least one membrane and further extends at least partially or completely to / through a first layer below the membrane, such as a sensing layer or a filling material layer.

[0197] In at least one opening of the exemplary third type, the opening can be formed so that it penetrates / extends through at least one membrane and further extends through any other layer below the membrane, including partially or completely extending through an electrode located below the membrane, such as through the first electrode / working electrode.

[0198] The opening may even extend partially through the substrate.

[0199] In other words, the depth of the at least one opening may vary and may increase from the exemplary first type to the exemplary third type in the described exemplary types.

[0200] This may further help optimize control of the analyte flux / analyte-carrying fluid to the electrodes of the analyte sensor (eg, to the first electrode / working electrode).

[0201] Furthermore, it is conceivable that the at least one film is applied / configured such that possible edges / borders / sides thereof can at least partially or completely surround edges / borders / sides of layers and / or components located beneath the at least one film.

[0202] For example, in a first type of edge of at least one membrane, the edge can be configured to wrap around a first layer below the membrane, such as a sensing layer or a filling material layer, such as in an L-shaped manner (e.g., the long side of the L is parallel to the substrate and the short side of the L is orthogonal to the substrate).

[0203] In an exemplary second type of edge of at least one membrane, the edge can be configured to wrap around all layers / all components below the membrane, such as sensing layers and filling material layers and electrodes, such as first electrodes / working electrodes, in the L-shaped manner until contacting the substrate.

[0204] The edge types and opening types described are merely exemplary and other types are also conceivable.

[0205] For example, the L-shape of the edge is not limited to the long or short sides of the L being linear straight sides, but the sides may be curved or may adapt to the shape of the cross-section of various layers, including non-rectangular cross-sections.

[0206] As described above, the analyte sensor may include a sensor circuit which, in addition to electrodes and possible other electronic components, may further include at least one capacitor.

[0207] Exemplary methods of operating an analyte sensor described herein may include one, some, or all of the following steps:

[0208] ● Apply a voltage signal between the first electrode / working electrode and the second electrode / counter electrode of the analyte sensor

[0209] ● an electrical signal between the first electrode and the second electrode via at least one capacitor

[0210] integrating an electrical signal (e.g., a current) generated in response to an electrochemical reaction of the first electrode with the analyte or a fluid carrying the analyte, the integration generating a voltage signal proportional to the charge of the at least one capacitor,

[0211] - Measure analyte data based on the generated voltage signal.

[0212] The electrochemical reaction of the first electrode with the analyte or the fluid carrying the analyte may occur in the above-mentioned electrochemically active layer or sensing layer of the first electrode.

[0213] The step of applying a voltage signal may in particular comprise applying a voltage from the outside, ie from a voltage source. However, this step may also comprise using a voltage / current generated by a spontaneous electrochemical reaction.

[0214] The accumulated integrated voltage then slowly reduces the current until it reaches zero.

[0215] An externally triggered short circuit (either across a measurement or resistor) discharges the capacitor.

[0216] This can be combined with disconnection of the sensor circuit to stop the electrochemical reaction. During the reaction stop step? Oxygen levels can recover, which changes the open circuit potential (OCP), while no current flows.

[0217] In other words, the step of applying a voltage signal may also include applying or performing an open circuit potential operation.

[0218] Evaluating the OCP as a function of time (e.g. at the beginning and end of an electrochemical reaction interruption) allows calculation of the required oxygen level and flux.

[0219] In addition to analyte data, such as concentration of an analyte, for example glucose concentration, other data may also be measured based on the generated voltage signal, such as oxygen data.

[0220] For example, the oxygen data may include oxygen saturation / oxygen saturation level / oxygen saturation concentration in a body fluid / analyte-carrying fluid of the patient or user (eg, in blood or interstitial fluid).

[0221] The measurement / determination of the data (e.g., analyte data and / or oxygen data) from the generated voltage signal may be highly accurate and reliable because the generated voltage signal is proportional to the data and because the analyte sensor described herein has good linear measurement characteristics.

[0222] The exemplary method may further include the step of periodically discharging the capacitor across a known resistor that determines the capacitance.

[0223] This can, in particular, ensure that the electrochemical potential difference between the electrodes of the analyte sensor is maintained at a level at which the electrochemical reaction between / at the electrodes can be driven at an optimal / maximum rate so that current can flow between the electrodes and can form the basis for the measurement of analyte data and / or oxygen data and / or other data.

[0224] The possible resistor may also be part of the sensor circuit of the analyte sensor.

[0225] Additionally, the electrodes may be periodically operated in an open circuit mode.

[0226] The measurable electrode voltage may then reflect the electrochemical potential difference between the first electrode / working electrode and the second electrode / counter electrode / combined counter / reference electrode.

[0227] At the same time, for example, at the first electrode / working electrode, the analyte (e.g., glucose) is available in excess, but controlled / regulated / limited by the membrane exemplarily described above, the oxygen reservoir at the second electrode / counter electrode may be depleted after a short time, for example within a few minutes.

[0228] Therefore, the difference in oxygen levels can dominate the change in open circuit potential.

[0229] Therefore, measuring the potential of the electrode at the beginning and end of the short open circuit phase, i.e. when the electrode of the analyte sensor is operated in said open circuit mode, can reveal sufficient information to:

[0230] a) reconstructing the total oxygen level at the analyte sensor location, and

[0231] b) Based on the recovery of the oxygen flux rate, the transport properties of the filler material or filler material layer or diffusion limiting layer can be measured, which in turn is proportional to the sensitivity of the analyte sensor.

[0232] For example, the sensitivity of an analyte sensor may be described by the differential slope of the current-glucose relationship.

[0233] Thus, other advantages of the operating schemes and designs of analyte sensors described herein may include:

[0234] ● Providing oxygen data (e.g., oxygen saturation / oxygen saturation level / oxygen saturation concentration in body fluids) as auxiliary data to the patient or user, which may provide particularly useful therapeutic information, such as indicating the presence of inflammation.

[0235] ●Reduce the power consumption of analyte sensors.

[0236] ● Reduce material wear at the second electrode / counter electrode, thereby extending the life of the analyte sensor.

[0237] For the sake of completeness, it should be noted that the analyte sensor may also be configured to harvest the voltage / current or energy generated by the electrochemical reaction at the electrodes of the analyte sensor and use the harvested energy for operation of the analyte sensor.

[0238] Furthermore, the analyte sensor may be configured for removable / detachable attachment to a mounting unit for placing the analyte sensor on the skin of a user and for holding the analyte sensor in place.

[0239] The mounting unit may further include an insertion component (eg, a cannula) configured to facilitate guidance of an end portion of an electrode of the analyte sensor during partial insertion of the electrode into the skin / body of a user for analyte and / or other measurements.

[0240] The exemplary mounting unit can be implemented as a patch unit, which can be configured to be removably attached to the skin / body of a user and can be configured to receive and retain an analyte sensor so that the analyte sensor can perform analyte measurements on the user over a period of time while being coupled to the user via the mounting unit / patch unit.

[0241] However, it is also conceivable that the mounting unit or the patch unit is integrated in the analyte sensor.

[0242] The analyte sensor may include a digital communication interface configured to transmit (eg, wirelessly) data measured by the analyte sensor, such as glucose, to a data analysis unit, such as a data analysis unit of a continuous analyte monitoring system.

[0243] However, the analyte sensor itself may include one or more processors for analyzing data measured by the analyte sensor, such as glucose data and / or oxygen data and / or other data.

[0244] The analyte sensor may also include a device for outputting analyte data (e.g., glucose data) and / or other data (e.g., oxygen data, such as oxygen saturation / oxygen saturation level / oxygen saturation concentration in a body fluid (e.g., blood or interstitial fluid)) measured by the analyte sensor and / or data obtained from the measured analyte data and / or other data via visual and / or auditory and / or tactile indications.

[0245] For example, the analyte sensor may include a display for displaying measured data, such as measured analyte data, such as glucose data or oxygen data, and other information.

[0246] Exemplary material properties of the at least one impermeable membrane

[0247] In the following, further exemplary possible properties of the at least one membrane exemplarily described above and herein of the analyte sensor are described, the membrane comprising a membrane material which is impermeable to the analyte / analyte-carrying fluid.

[0248] For example, the exemplary impermeable membrane material or nearly impermeable membrane material may refer to a membrane material characterized by having a water absorption of less than 5 weight % or less than 2 weight % or less than 1 weight % based on the total weight of at least one membrane, as determined according to the American Society for Testing and Materials standard ASTM 570.

[0249] In other words, the exemplary membrane / membrane material may be hydrophobic.

[0250] The exemplary membrane / membrane material may include a polymer, particularly a hydrophobic polymer, wherein, for example, the exemplary hydrophobic polymer is characterized in that it has a water absorption of less than 5 weight % or less than 2 weight % or less than 1 weight % based on the total weight of the hydrophobic polymer or membrane, as determined according to the American Society for Testing and Materials standard ASTM 570.

[0251] Furthermore, the exemplary hydrophobic polymer may be a thermoplastic hydrophobic polymer.

[0252] For example, the glass transition temperature of the hydrophobic polymer may be in the range of -100°C to 0°C, preferably in the range of -70°C to -50°C.

[0253] Herein, the glass transition temperature may be measured via differential scanning calorimetry using heating and cooling at a ramp rate of 10° C. / min, wherein the glass transition temperature may be measured during the second heating cycle.

[0254] In other words, the hydrophobic polymer may first be heated at a ramp rate of 10°C / min, then it may be cooled at a ramp rate of 10°C / min, and then it may be heated again at a ramp rate of 10°C / min to determine the glass transition temperature.

[0255] Said glass transition temperature / glass transition temperature range may be particularly advantageous, since it may lead to a sufficiently high stability of the membrane / membrane material. The membrane / membrane material may then act as a protective layer for the analyte sensor, i.e. for the electrodes, such that if, for example, the analyte sensor is bent, in particular during use, the protective layer will maintain its integrity and may protect the underlying analyte sensor components (e.g. electrodes, sensor circuitry and other electronic components) from damage.

[0256] Furthermore, the hydrophobic polymer may be characterized, for example, by a crystallization temperature in the range of 50° C. to 100° C., such as in the range of 75° C. to 85° C. The crystallization temperature may be measured via differential scanning calorimetry using the same parameters as the glass transition temperature.

[0257] Furthermore, possible exemplary hydrophobic polymers for / for at least one membrane may be selected from the group consisting of polyurethanes, polyureas, polyolefins, poly(meth)acrylates, polyesters, polyethers, polyamides, polyvinyl chloride, polyvinyl butyral-co-vinyl alcohol-co-vinyl acetate, silicones, epoxy resins and UV-hardening resins.

[0258] Particularly preferred are polyurethanes and / or UV (ultraviolet light) hardening resins. In addition to the at least one polymer, the at least one film may also comprise electrically conductive particles, for example electrically conductive carbon particles.

[0259] Therefore, the analyte sensor may be preferred, wherein at least one membrane comprises at least one polymer selected from the group consisting of polyurethane, polyurea, polyolefin, poly(meth)acrylate, polyester, polyether, polyamide, polyvinyl chloride, polyvinyl butyral-co-vinyl alcohol-co-vinyl acetate and UV hardening resin. Particularly preferred may be polyurethane and / or UV hardening resin.

[0260] Particularly suitable polyureas may be selected from the group consisting of hydrophobic polyureas.

[0261] Particularly suitable polyolefins may be selected from the group consisting of aliphatic polyolefins and aromatic polyolefins, in particular from the group consisting of polyethylene, polypropylene, polybutylene, polyisoprene, polybutadiene and polystyrene.

[0262] In the context of the present invention, the term poly(meth)acrylate relates to polyacrylates and polymethacrylates. A particularly suitable polymethacrylate is, for example, butyl methacrylate.

[0263] Particularly suitable polyesters may be selected from the group consisting of polyethylene terephthalate (PET) and polycarbonate.

[0264] Particularly suitable polyethers may be selected from the group consisting of polytetrahydrofuran (PTHF) and polyacetals, which are also called polyoxymethylene (POM).

[0265] Particularly suitable UV curable resins may be selected from the group consisting of acrylated silicones, acrylated urethanes, acrylated epoxides and UV curable ester resins, such as acrylated polyesters.

[0266] Particularly suitable polyurethanes may be selected from the group consisting of hydrophobic polyurethanes, in particular hydrophobic thermoplastic polyurethanes (TPU).

[0267] The hydrophobic thermoplastic polyurethane may include hard segments and soft segments in different ratios. Suitable hard segments generally include the polymerization product of diisocyanates and polyols. Suitable diisocyanates may be aliphatic diisocyanates or aromatic diisocyanates, preferably aliphatic diisocyanates.

[0268] Suitable aromatic diisocyanates are, for example, 4,4′-methylenediphenyl diisocyanate and / or toluene-2,4-diisocyanate.

[0269] Suitable aliphatic diisocyanates are, for example, hexamethylene diisocyanate and / or isophorone diisocyanate.

[0270] Suitable polyols are preferably diols, such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and / or 1,10-decanediol.

[0271] Suitable soft segments may include polyethers and / or polyesters. Suitable polyethers are, for example, polyethylene oxide and / or polytetrahydrofuran, while suitable polyesters are, for example, polyethylene terephthalate and / or polyethylene naphthalate.

[0272] Exemplary properties of filler material / filler material layer / diffusion limiting layer

[0273] In the following, further exemplary possible properties of the material / layer / filling material / filling layer / diffusion limiting layer discussed further above and exemplarily herein are described, which is permeable to the analyte-carrying fluid / analyte and with which at least one opening of the at least one membrane can be filled.

[0274] As mentioned above, the filling material / filling layer / diffusion limiting layer may include at least one polymeric material, such as a hydrophilic polymer.

[0275] Suitable polymeric materials may for example be selected from the group consisting of copolymers based on polyvinylpyridine, polyurethanes and hydrogels. Copolymers based on polyvinylpyridine are particularly suitable.

[0276] Suitable hydrogels are in particular polyethylene glycol copolymers (PEG copolymers), polyvinyl acetate copolymers (PVA copolymers), poly(2-alkyl-2-oxazoline) copolymers, polyacrylates and / or methacrylate-acrylate copolymers or block copolymers, in particular polyacrylates and / or methacrylate-acrylate copolymers or block copolymers comprising hydrophilic side groups. Thus, for example, suitable hydrogels can be selected from the group consisting of (hydroxyethyl) methacrylate (HEMA) homopolymers, HEMA copolymers, silicone hydrogels and HEMA-co-N-vinylpyrrolidone polymers, each of which can include side groups selected from the group consisting of methacrylic acid, glyceryl methacrylate, N,N-dimethylacrylamide and phosphorylcholine.

[0277] In particular, the weight average molecular weight (MW) of the polymeric material may be greater than 10.000 kDa. More particularly, the weight average molecular weight (MW) of the polymeric material may be greater than 50.000 kDa, or even greater than 100.000 kDa. Particularly suitable are polymeric materials having a weight average molecular weight (MW) of 10.000 to 500.000 kDa.

[0278] The analyte sensor described above and exemplarily herein can be part of a continuous analyte monitoring system (e.g., a continuous glucose monitoring (CGM) system), which includes: a medical device comprising an analyte sensor as exemplarily described herein and one or more processors configured to process data collected by the analyte sensor.

[0279] In addition, the analyte sensor exemplarily described above and in this article can be part of a kit, which includes: at least one analyte sensor as described above, and at least one mounting unit, such as a patch unit, which is configured to place the at least one analyte sensor on the skin of a user and to which the at least one analyte sensor can be detachably coupled.

[0280] The following figures illustrate the following aspects of the invention.

[0281] FIG. 1a : Exemplary structure / exemplary structural aspects of a first electrode / working electrode of an exemplary analyte sensor

[0282] FIG. 1 b : Exemplary alternative structures / example alternative structural aspects of a first electrode / working electrode of an exemplary analyte sensor

[0283] FIG. 1c : Exemplary further alternative structure of the first electrode / working electrode of an exemplary analyte sensor /

[0284] Exemplary Further Alternative Structural Aspects

[0285] FIG. 1d : Exemplary structure / example structural aspects of a second electrode / counter electrode of an exemplary analyte sensor

[0286] FIG. 1e : Example cross section of an example analyte sensor

[0287] FIG. 2 : Exemplary flow chart of an exemplary method for assembling / manufacturing an exemplary analyte sensor

[0288] FIG. 3 : Example flow chart of an example method for operating an example analyte sensor

[0289] FIG. 1 a shows an exemplary cross-section of a portion of an exemplary analyte sensor illustrating a possible multi-layer structure 110 of a first electrode / working electrode 101 of the analyte sensor.

[0290] The second electrode / counter electrode is not shown.

[0291] The analyte sensor may include a substrate 100 , as further described above, which may carry the various layers and components of the analyte sensor.

[0292] For example, the first electrode / working electrode 101 and the sensor circuitry / together with the sensor circuitry may be mounted directly onto the top surface 113 of the substrate 100 .

[0293] The (not shown) second / counter electrode and its various layers and components may then be mounted, for example, to the bottom surface 112 of the substrate 100 .

[0294] The first electrode / working electrode 101 may be covered by / may include a sensing layer 102 / sensing material, as further described above.

[0295] Furthermore, the first electrode / working electrode 101 may be covered by at least one membrane 104 and may be applied / mounted / arranged above the sensing layer 102 as further described above. Also as described above, the membrane 104 may comprise a membrane material that is impermeable to the analyte or the fluid carrying the analyte.

[0296] At least one membrane 104 comprises at least one opening. In the present case, three exemplary openings 107, 108, 109 are shown / visible and the analyte or the fluid carrying the analyte can pass through these openings.

[0297] At least one opening may be filled with a material 103 permeable to the analyte / analyte-carrying fluid, such as a hydrophilic polymer. In the example shown, all openings 107, 108, 109 are completely filled with a material 103 permeable to the analyte / analyte-carrying fluid.

[0298] In the example shown, the filling material 103 permeable to the analyte-carrying fluid also covers the at least one membrane 104, i.e. the filling material 103 / filling layer is embedded in the at least one membrane 104. The filling material layer may also be referred to as a diffusion limiting layer, as it may control the diffusion of the analyte / analyte-carrying fluid through the openings 107, 108, 109.

[0299] As mentioned above, the at least one opening / multiple openings of the membrane may be of different types / different depths. In the case of multiple openings, all openings may be of the same type or of different types, or may be grouped into groups of different types.

[0300] In the example shown, three exemplary possible different opening types are described.

[0301] For example, opening 107 illustrates an exemplary first type, wherein the opening is formed such that it only penetrates / extends through membrane 104 , and does not penetrate / extend to any possible other layers of the analyte sensor below membrane 104 .

[0302] For example, opening 108 illustrates an exemplary second type, wherein the opening is formed such that it penetrates / extends through at least one membrane and further extends at least partially or completely to / through a first layer beneath the membrane, such as, as shown, sensing layer 102 .

[0303] For example, opening 109 illustrates an exemplary third type, wherein the opening can be formed such that it penetrates / extends through at least one membrane and further extends through any other layer below the membrane, including partially or completely extending through an electrode located below the membrane, such as in the example shown, opening 109 extends through / extends through membrane 104, sensing layer 102 and first electrode / working electrode 101.

[0304] As also mentioned before, at least one film may be applied / configured such that possible edges / borders / sides thereof may at least partially or completely surround edges / borders / sides of layers and / or components located beneath the at least one film.

[0305] Here, two exemplary possible edge types are described.

[0306] For example, at least one edge 105 of the membrane shown is of a first type, wherein the edge is configured to wrap around a first layer 102 below the membrane, such as a sensing layer 102, in an L-shaped manner (e.g., the long side of the L is parallel to the substrate 100 and the short side of the L is orthogonal to the substrate 100).

[0307] The shown edge 106 of at least one membrane is of the second type, wherein the edge is configured to wrap around all layers / components below the membrane in said L-shaped manner, e.g. around the sensing layer 102 and around electrodes, e.g. around the first electrode / working electrode, until contacting / touching the substrate 100.

[0308] The edge types of all possible different edges of the at least one membrane may be of the same type or of different types.The configurations shown are exemplary only.

[0309] An exemplary orthogonal reference frame 111 indicates an orientation of FIG. 1 a and its components wherein top and bottom surfaces 113 , 112 of substrate 100 are parallel to each other and to a horizontal x-axis, and wherein, for example, an orthogonal y-axis is aligned or parallel to the direction of Earth's gravity.

[0310] FIG. 1 b shows an exemplary cross-section of a portion of an exemplary alternative analyte sensor illustrating an alternative possible multi-layer structure 210 for the first electrode / working electrode 201 of the analyte sensor.

[0311] The second electrode / counter electrode is not shown.

[0312] The analyte sensor may include a substrate 200 , as further described above, which may carry the various layers and components of the analyte sensor.

[0313] For example, the first electrode / working electrode 201 and the sensor circuitry / together with the sensor circuitry may be mounted directly onto the top surface 213 of the substrate 200 .

[0314] The (not shown) second / counter electrode and its various layers and components may then be mounted, for example, to the bottom surface 212 of the substrate 200 .

[0315] The first electrode / working electrode 201 may be covered by / may include a sensing layer 202 / sensing material, as further described above.

[0316] Furthermore, the sensing layer 202 / sensing material may be covered by at least one layer of a filling material 203 that is permeable to the analyte-carrying fluid.

[0317] At least one membrane 204 may be applied / mounted / arranged over the sensing layer 202 and may wrap / embed the filling material / filling material layer 203 and the sensing layer 202 .

[0318] As described above, the membrane 204 may include a membrane material that is impermeable to the analyte or the fluid carrying the analyte, and the membrane 204 may include openings 207 , 208 , 209 through which the analyte or the fluid carrying the analyte may pass.

[0319] An exemplary edge of at least one membrane 204 is exemplarily shown as the second type, wherein the edge is configured to surround all layers / all components below the membrane in the L-shaped manner, for example, surrounding the filling material layer 203, the sensing layer 202, the electrodes, for example, surrounding the first electrode / working electrode, until contacting / touching the substrate 200.

[0320] In the example shown, three exemplary openings 207 , 208 , 208 of the at least one membrane 204 are shown / visible, wherein the openings are all of the same exemplary type.

[0321] More specifically, the openings are all of the exemplary first type, wherein the openings are formed such that they penetrate / extend only through the membrane 204 and do not penetrate / extend to any possible other layers of the analyte sensor below the membrane 204, for example, as shown here, the openings do not penetrate / extend through the filling material layer 203, do not penetrate the sensing layer 202 and do not penetrate the first electrode / working electrode 201.

[0322] However, it is also conceivable that the openings penetrate all layers 203 , 202 , 201 and the components carried by the substrate 200 , and may even extend partially into the substrate.

[0323] Exemplary orthogonal reference frame 211 is identical to orthogonal reference frame 111 and indicates an orientation of FIG. 1b and its components wherein top surface 213 and bottom surface 212 of substrate 200 are parallel to each other and to the horizontal x-axis, and wherein, for example, the orthogonal y-axis is aligned or parallel to the direction of Earth's gravity.

[0324] FIG. 1 c shows an exemplary cross-section of a portion of an exemplary other alternative analyte sensor illustrating another alternative possible multi-layer structure 510 for the first electrode / working electrode 501 of the analyte sensor.

[0325] The second electrode / counter electrode is not shown.

[0326] The analyte sensor may include a substrate 500 , as further described above, which may carry the various layers and components of the analyte sensor.

[0327] For example, the first electrode / working electrode 501 and the sensor circuitry / together with the sensor circuitry may be mounted directly onto the top surface 507 of the substrate 500 .

[0328] The (not shown) second / counter electrode and its various layers and components may then be mounted, for example, to the bottom surface 508 of the substrate 500 .

[0329] The first electrode / working electrode 501 may include a sensing layer 502 / sensing material, as further described above, which, in contrast to the multilayer structure of FIGS. 1 a and 1 b , may be in direct contact with the substrate 500 , ie, in direct contact with the top surface 507 of the substrate 500 .

[0330] In other words, the sensing layer 502 / sensing material may be arranged below the first electrode / working electrode 501 .

[0331] Instead of having a dedicated membrane having a membrane material that is impermeable to the analyte or the analyte-carrying fluid and having an opening through which the analyte or the analyte-carrying fluid can pass, as in the case of the embodiments of Figures 1a and 1b, it is the first electrode / working electrode 501 itself that acts as the analyte flux localizing component.

[0332] In other words, the working electrode 501 may include a material that is impermeable to the analyte or the fluid carrying the analyte, such as carbon, but the working electrode may also include openings 505, 506, through which the analyte or the fluid carrying the analyte can pass to contact the electrochemically active layer (e.g., the sensing layer 502).

[0333] The openings of the working electrode 501 may be of the same or similar type as described above. In the example shown, the opening 505 penetrates the working electrode 501 but not the sensing layer 502 , and the opening 506 penetrates the working electrode 501 and the sensing layer 502 but not into the substrate 500 .

[0334] The edge of the working electrode 501 can also be configured in different ways. In the example shown, the edge 504 surrounds the edge or side of the sensing layer 502.

[0335] The openings 505, 506 of the working electrode 501 may be filled with a material 503 permeable to the analyte-carrying fluid, such as a hydrophilic polymer. In the example shown, all openings 505, 506 are completely filled with a material 503 permeable to the analyte-carrying fluid.

[0336] In the example shown, the filling material 503 which is permeable to the analyte-carrying fluid also covers the working electrode, ie the filling material 503 / filling layer is embedded in the working electrode.

[0337] An exemplary orthogonal reference frame 509 indicates an orientation of FIG. 1c and its components, wherein top surface 507 and bottom surface 508 of substrate 500 are parallel to each other and to a horizontal x-axis, and wherein, for example, an orthogonal y-axis is aligned or parallel to the direction of Earth's gravity.

[0338] FIG. 1 d shows an exemplary cross-section of a portion of an exemplary analyte sensor illustrating a possible multi-layer structure 610 of a second electrode / counter electrode 601 of the analyte sensor.

[0339] First electrode / working electrode not shown

[0340] The analyte sensor may include a substrate 600 , as further described above, which may carry the various layers and components of the analyte sensor.

[0341] 1a , 1b and 1c , the orientation of FIG. 1d is such that the substrate has been rotated 180° as shown in orthogonal reference frame 607 , ie the shown upper surface of the substrate is actually the bottom surface 605 of the substrate in orthogonal reference frames 111 , 211 , 509 .

[0342] For example, the second electrode / counter electrode 601 and sensor circuit components may be mounted directly onto the bottom surface 605 of the substrate 600 .

[0343] The (not shown) first / working electrode and its various layers and components may then be mounted, for example, to the top surface 606 of the substrate 600 .

[0344] The second electrode / counter electrode 601 may be covered by a sensing material layer 602 .

[0345] Furthermore, a filler material layer / diffusion limiting layer 603 that is permeable to the analyte and / or the fluid carrying the analyte may cover the sensing material layer 602 .

[0346] 1 e illustrates an exemplary cross-section of a portion of an exemplary analyte sensor, wherein first / working electrode 701 and second / counter electrode 801 attached to opposite sides of substrate 700 are both visible.

[0347] In this example, the multilayer structure 711 of the working electrode 701 is mounted to the top surface 705 of the substrate 700 and corresponds to the multilayer structure 110 of the working electrode 101 described in FIG. 1 a .

[0348] Thus, the working electrode 701 may be covered by / may include a sensing layer 702 / sensing material, as further described above.

[0349] The sensing layer 702 may be covered by at least one film 704 .

[0350] The membrane 704 may comprise a membrane material that is impermeable to the analyte or the fluid carrying the analyte and may comprise openings 707, 708, 709 through which the analyte or the fluid carrying the analyte may pass. The openings are of different exemplary types as described in FIG. 1a.

[0351] In the example shown, the openings 707 , 708 , 709 are completely filled with a filling material 703 that is permeable to the analyte / analyte-carrying fluid.

[0352] In the example shown, the filling material 703 permeable to the analyte-carrying fluid also covers at least one membrane 704, i.e. the filling material 103 or a filling material layer is embedded in at least one membrane 704. The filling material layer may also be referred to as a diffusion limiting layer, since it may control the diffusion of the analyte / analyte-carrying fluid through the openings 707, 708, 709.

[0353] In this example, the multilayer structure 804 of the counter electrode 801 is mounted to the bottom surface 706 of the substrate 700 and corresponds to the multilayer structure 610 of the counter electrode 601 described in FIG. 1 d .

[0354] The counter electrode 801 may be covered by a sensing material layer 802 .

[0355] Furthermore, a filler material layer / diffusion limiting layer 803 that is permeable to the analyte and / or the fluid carrying the analyte may cover the sensing material layer 802 .

[0356] The combinations and arrangements of the multilayer structures of working electrodes and counter electrodes shown here are merely exemplary. Other combinations are conceivable. For example, a combination of the embodiment according to FIG. 1 b or FIG. 1 c with the embodiment according to FIG. 1 d.

[0357] Although in the example shown, the working electrode 701 and the counter electrode 801 are arranged directly opposite each other on different sides of the substrate, they can also be arranged with an offset from each other, such as a horizontal offset along the x-axis.

[0358] It is also conceivable that the working electrode 701 and the counter electrode 801 are coplanarly arranged on the same side (eg, top surface) of the substrate.

[0359] FIG2 illustrates an exemplary flow chart of an exemplary method 300 for assembling / manufacturing an exemplary analyte sensor of the exemplary type described above, which may be used in a medical device or a medical continuous monitoring device for measuring analyte data in an analyte-carrying fluid of a patient, in particular for measuring glucose data and / or oxygen data and / or other data.

[0360] The exemplary method may include the step of mounting 301 a sensor circuit including a first electrode (i.e., a working electrode) and a second electrode (i.e., a counter electrode) onto a substrate. The first electrode and the second electrode may be arranged on opposite sides or opposite surfaces of the substrate, or on the same side or the same surface of the substrate.

[0361] The method may further comprise the steps of applying 302 at least one membrane comprising a membrane material that is impermeable to the analyte and / or to the fluid carrying the analyte, and completely or at least partially covering the first electrode with the at least one membrane. Optionally, the second electrode / counter electrode may also be completely or at least partially covered by the at least one membrane.

[0362] The method may in particular further comprise forming at least one opening in the membrane, for example by drilling and / or an ablation process, for example by laser ablation.

[0363] The one or more openings in the membrane are formed in a portion of the membrane that completely or at least partially covers the first electrode / counter electrode.

[0364] Additionally, the openings in the membrane may be at least partially filled with a filling material that is permeable to the analyte-carrying fluid and / or the analyte, such as a hydrophilic polymer.

[0365] Furthermore, the filler material may be applied to form a filler material layer covering and / or embedding the membrane. The filler material layer may also be referred to as a diffusion limiting layer.

[0366] Additionally, a layer of filling material may also be applied to cover the second electrode / counter electrode.

[0367] As mentioned before, the electrodes (eg the first electrode / working electrode and / or the second electrode / counter electrode) may be configured or may be provided with an electrochemically active layer, ie with a layer of sensing material as described above.

[0368] Exemplary steps for applying layers or films to the analyte sensor and its components may include a dip coating step.

[0369] FIG. 3 illustrates an exemplary flow chart of an exemplary method 400 for operating an exemplary analyte sensor of the exemplary type described above, which may include the step of applying 401 a voltage signal between a first electrode and a second electrode.

[0370] The method may further include the step of integrating 402 an electrical signal (e.g., a current) between the first electrode and the second electrode via at least one capacitor, wherein the electrical signal is generated in response to an electrochemical reaction of the first electrode with an analyte or a fluid carrying an analyte, and wherein the integration generates a voltage signal that is proportional to the charge of the at least one capacitor.

[0371] The generated voltage signal may then be used as a basis for measuring 403 analyte data and / or oxygen data and / or other data using the analyte sensor.

[0372] Additionally, the method may include periodically operating the electrode in an open circuit mode.

[0373] Next, reference is made to FIGS. 1 a , 1 b , 1 c , 1 d , 1 e , 2 and 3 , wherein reference characters denote the following exemplary aspects, exemplary features and exemplary steps.

[0374] 100 Example substrate

[0375] 101 Exemplary First Electrode / Working Electrode

[0376] 102 Exemplary sensing layer / sensing material / electrochemically active layer

[0377] 103 Example filler material / filler material layer of material, which is permeable to analyte / analyte-carrying fluid, example diffusion limiting layer

[0378] 104 Exemplary membrane / membrane layer / membrane material, which is impermeable to analyte / analyte-carrying fluid, exemplary flux positioning membrane / flux positioning layer

[0379] 105 Example edge of film, example first type edge

[0380] 106 Example edge of film, example second type edge

[0381] 107 Exemplary openings in membranes, exemplary first type of openings

[0382] 108 Exemplary openings in membranes, exemplary second type of openings

[0383] 109 Exemplary openings in membranes, exemplary third type of openings

[0384] 110 Exemplary structure, exemplary multilayer structure of analyte sensor / first electrode / working electrode

[0385] 111 Example of orthogonal reference system

[0386] 112 Exemplary bottom surface of substrate

[0387] 113 Exemplary top surface of substrate

[0388] 200 Example substrate

[0389] 201 Exemplary first electrode / working electrode

[0390] 202 Exemplary sensing layer / sensing material

[0391] 203 Example filler material / filler material layer of material, which is permeable to analyte / analyte-carrying fluid, example diffusion limiting layer

[0392] 204 Exemplary membrane / membrane layer / membrane material, which is impermeable to analyte / analyte-carrying fluid, exemplary flux positioning membrane / flux positioning layer

[0393] 205 Example edge of film, example second type edge

[0394] 206 Exemplary edge of film, exemplary second type of edge

[0395] 207 Exemplary openings in membrane, exemplary first type of openings

[0396] 208 Exemplary openings in membrane, exemplary first type of openings

[0397] 209 Exemplary openings in membrane, exemplary first type of openings

[0398] 210 Exemplary structure, exemplary multilayer structure of analyte sensor / first electrode / working electrode

[0399] 211 Exemplary Orthogonal Reference Systems

[0400] 212 Exemplary bottom surface of substrate

[0401] 213 Exemplary top surface of substrate

[0402] 300 Example Method for Assembling / Manufacturing Example Analyte Sensor

[0403] 301, 302 Exemplary method steps

[0404] 400 Exemplary Methods for Operating an Exemplary Analyte Sensor

[0405] 401, 402, 403 Exemplary method steps

[0406] 500 Example substrate

[0407] 501 Exemplary First Electrode / Working Electrode

[0408] 502 Exemplary sensing layer / sensing material / electrochemically active layer

[0409] 503 Example filler material / filler material layer of material, which is permeable to analyte / analyte-carrying fluid, example diffusion limiting layer

[0410] 504 Example edge of working electrode

[0411] 505 Example opening

[0412] 506 Example opening

[0413] 507 Exemplary top surface of substrate

[0414] 508 Exemplary bottom surface of substrate

[0415] 509 Exemplary Orthogonal Reference System

[0416] 600 Example substrate

[0417] 601 Exemplary Second Electrode / Counter Electrode

[0418] 602 Exemplary sensing layer / sensing material / electrochemically active layer

[0419] 603 Example filler material / filler material layer of material, which is permeable to analyte / analyte-carrying fluid, example diffusion limiting layer

[0420] 605 Exemplary bottom surface of substrate

[0421] 606 Exemplary top surface of substrate

[0422] 607 Exemplary Orthogonal Reference System

[0423] 700 Example substrate

[0424] 701 Exemplary First Electrode / Working Electrode

[0425] 702 Exemplary sensing layer / sensing material / electrochemically active layer

[0426] 703 Example filler material / filler material layer of material, which is permeable to analyte / analyte-carrying fluid, example diffusion limiting layer

[0427] 704 Exemplary membrane / membrane layer / membrane material, which is impermeable to analyte / analyte-carrying fluid, exemplary flux positioning membrane / flux positioning layer

[0428] 705 Exemplary top surface of substrate

[0429] 706 Exemplary bottom surface of substrate

[0430] 707 Example opening

[0431] 708 Example opening

[0432] 709 Example opening

[0433] 710 Exemplary structure, exemplary multilayer structure of analyte sensor

[0434] 711 Exemplary structure, exemplary multilayer structure of a working electrode of an analyte sensor

[0435] 712 Exemplary Orthogonal Reference Systems

[0436] 801 Exemplary Second Electrode / Counter Electrode

[0437] 802 Exemplary sensing layer / sensing material / electrochemically active layer

[0438] 803 Example filler material / filler material layer of material, which is permeable to analyte / analyte-carrying fluid, example diffusion limiting layer

[0439] 804 Exemplary structure, exemplary multilayer structure of a counter electrode of an analyte sensor

Claims

1. An analyte sensor for use in a medical device for measuring analyte data in an analyte-carrying fluid, in particular for measuring glucose data, the analyte sensor comprising: a first electrode (101), which is a working electrode, The second electrode, a substrate (100) carrying the first electrode and the second electrode, at least one membrane (104) at least partially covering the first electrode (101), wherein the at least one membrane (101) comprises a membrane material that is impermeable to the analyte-carrying fluid and / or the analyte, wherein the at least one membrane comprises at least one opening (107), And wherein the at least one membrane (104) is configured to control the flux of the analyte-carrying fluid and / or the analyte to the first electrode (101) via the at least one opening (107).

2. The analyte sensor according to the preceding claim, wherein the diameter of the at least one opening (107) is similar to the thickness of the at least one membrane (104), for example in the range of 10 to 100 micrometers.

3. The analyte sensor according to one of the preceding claims, wherein the at least one opening (107) has been formed by a laser ablation process.

4. An analyte sensor according to one of the preceding claims, wherein the at least one opening (107) is at least partially filled with a material (103) that is permeable to the analyte-carrying fluid and / or the analyte, such as a hydrophilic polymer optionally selected from the group consisting of: polyvinylpyridine-based copolymers, polyurethanes and hydrogels.

5. The analyte sensor according to the preceding claim, wherein the material (103) permeable to the analyte-carrying fluid and / or the analyte at least partially covers the first electrode (101) and / or the second electrode.

6. The analyte sensor according to one of the preceding claims, wherein the membrane (104) is hydrophobic.

7. The analyte sensor according to one of the preceding claims, further comprising a sensing layer (102), wherein the sensing layer (102) is configured for providing at least one enzyme to the first electrode (101).

8. The analyte sensor according to one of the preceding claims, wherein the first electrode (101) and the second electrode are arranged on opposite sides of the substrate (100).

9. An analyte sensor according to one of the preceding claims, wherein the second electrode is an electrode selected from the group comprising: a counter electrode and a combined counter / reference electrode, and / or wherein the second electrode is an oxygen electrode configured to use oxygen dissolved in the analyte-carrying fluid as an electron acceptor and wherein the second electrode may include gold or platinum as the conductive material.

10. A method (300) for manufacturing an analyte sensor according to any one of the preceding claims, the analyte sensor being used in a medical device for measuring analyte data, in particular for measuring glucose data, in an analyte-carrying fluid, the method comprising: A sensor circuit comprising a first electrode and a second electrode is mounted (301) on a substrate, wherein the first electrode is a working electrode, applying (302) at least one membrane comprising a membrane material that is impermeable to the analyte-carrying fluid and / or the analyte, and at least partially covering the first electrode with the at least one film, At least one opening is formed in the film, for example by drilling and / or ablation processes, for example by laser ablation, and optionally The at least one opening in the membrane is at least partially filled with a material (103) that is permeable to the analyte-carrying fluid and / or permeable to the analyte.

11. An analyte sensor for use in a medical device for measuring analyte data in an analyte-carrying fluid, in particular for measuring glucose data, the analyte sensor comprising: a first electrode (101), which is a working electrode, and The second electrode, a substrate (100) carrying the first electrode and the second electrode, wherein the first electrode comprises a material that is impermeable to the analyte-carrying fluid and / or impermeable to the analyte, and wherein the first electrode comprises at least one opening, And wherein the first electrode is configured to control a flux of the analyte-carrying fluid and / or the analyte to the electrochemically active layer of the first electrode via the at least one opening.

12. A method (400) for operating an analyte sensor according to one of the preceding analyte sensor claims 1 to 11, the method comprising: applying (401) a voltage signal between the first electrode and the second electrode, integrating (402) an electrical signal, such as a current, between the first electrode and the second electrode via at least one capacitor, wherein the electrical signal is generated in response to an electrochemical reaction of the first electrode with an analyte or a fluid carrying the analyte, the integration generating a voltage signal proportional to the charge of the at least one capacitor, Analyte data is measured (403) based on the generated voltage signal.

13. The method (400) according to the preceding claim, wherein the electrodes are periodically operated in an open circuit mode.

14. A continuous analyte monitoring system, such as a continuous glucose monitoring system, It includes: Medical device comprising an analyte sensor according to one of the preceding analyte sensor claims and one or more processors configured for processing data collected by the analyte sensor.

15. A kit comprising: at least one analyte sensor according to one of the preceding analyte sensor claims, At least one mounting unit, such as a patch unit, is configured for placing the at least one analyte sensor on the skin of a user and the at least one analyte sensor may be detachably coupled to the at least one mounting unit.

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