Working electrode for glucose monitoring probes with reduced interference

Abstract

The present disclosure relates to a working electrode of a glucose monitoring probe that reduces interference, comprising a base layer, a sensing layer, a semipermeable membrane, and a biocompatible membrane, wherein the base layer is disposed on a flexible substrate; the sensing layer is formed on the base layer by coating a sensing layer reagent, which is capable of chemically reacting with glucose in blood or tissue fluid, wherein the sensing layer reagent comprises a redox polymer, a glucose enzyme, a carbon nanotube, and a cross-linking agent, wherein amino groups are added to the carbon nanotubes to tightly form a covalent bond between the redox polymer and the carbon nanotubes and bind to the glucose enzyme, thereby reducing the working voltage required for the working electrode under the catalytic action of the carbon nanotubes, wherein the glucose enzyme is glucose oxidase; the semipermeable membrane is formed on the sensing layer to control the passage rate of glucose molecules; and the biocompatible membrane is formed on the semipermeable membrane. According to the present disclosure, a working electrode of a glucose monitoring probe that can reduce interference is provided.

Description

[0001] This application is filed on March 31, 2020 , application number is 202010246108.4, invention name is Grape Working electrode of sugar monitoring probe and manufacturing method thereof A divisional application for a patent application. Technical Field

[0002] The present disclosure relates to the field of glucose monitors, and in particular to a working electrode of a glucose monitoring probe capable of reducing interference. Background Art

[0003] Biosensors are analytical devices that tightly integrate biomaterials, bioderived materials, or biomimetic materials with optical, electrochemical, temperature, piezoelectric, magnetic, or micromechanical physicochemical sensors or sensing microsystems. To date, the most commercially successful biosensor is the amperometric enzymatic glucose sensor. These sensors hold nearly 85% of the global market share. Amperometric enzymatic glucose sensors are used to detect diabetes, and their increasing market share reflects the increasing prevalence of diabetes.

[0004] Diabetes mellitus is a syndrome characterized by a series of metabolic disorders involving sugar, protein, fat, water, and electrolytes. It is caused by various pathogenic factors, including genetic factors, immune dysfunction, microbial infections, and their toxins, which lead to pancreatic dysfunction and insulin resistance. If diabetes is not well controlled, it can lead to complications such as ketoacidosis, lactic acidosis, chronic renal failure, and retinopathy. With its increasing incidence, diabetes has become a global public health concern.

[0005] Currently, there is no cure for diabetes, only control methods. For diabetic patients, if they can continuously monitor their glucose levels in real time, they can prioritize reducing and minimizing the incidence of complications such as hypoglycemia and hyperglycemia in insulin-dependent diabetics.

[0006] Typically, glucose monitoring requires a glucose meter using an amperometric enzymatic glucose sensor. The sensor probe of a glucose meter is typically implanted in the body and monitors glucose concentrations in the interstitial fluid, as well as surrounding blood flow, metabolic rate, and the rate of change in glucose concentration in the blood vessels. Studies have shown that changes in interstitial fluid glucose concentrations typically lag behind changes in blood glucose concentrations by 2-45 minutes, with an average delay of approximately 6.7 minutes. However, when blood glucose concentrations begin to decrease, the interstitial fluid glucose concentration decreases before the blood glucose concentration, indicating that a decrease in interstitial fluid glucose concentration can predict impending hypoglycemia.

[0007] With the advancement of technology, a variety of portable glucose monitors have become popular, especially implantable continuous glucose monitoring devices, which are favored by diabetic patients and major hospitals. However, the service life of implantable continuous glucose monitors is often short and they are easily affected by immune responses and other impurities in the blood, which reduces their sensitivity. Therefore, how to better construct detection devices, extend the service life of glucose monitor sensor probes, and reduce the impact of other factors has become a major challenge. Summary of the Invention

[0008] The present disclosure is made in view of the above situation, and its purpose is to provide a working electrode of a glucose monitoring probe and a manufacturing method thereof, which prolongs the service life of the probe, reduces interference and improves the reaction sensitivity to glucose.

[0009] To this end, one aspect of the present disclosure provides a working electrode of a glucose monitoring probe, characterized in that the working electrode comprises: a base layer, which is arranged on a flexible substrate; a sensing layer, which is formed on the base layer by coating a sensing layer reagent and can chemically react with glucose in blood or tissue fluid, the sensing layer reagent comprising a metal polymer, glucose enzyme, carbon nanotubes and a cross-linking agent, the carbon nanotubes adsorbing the metal polymer and the glucose enzyme, and adding amino modification to the carbon nanotubes so that the metal polymer and the carbon nanotubes are tightly covalently bonded and combined with the glucose enzyme; a semipermeable membrane, which is formed on the sensing layer to control the passage rate of glucose molecules; and a biocompatible membrane, which is formed on the semipermeable membrane.

[0010] In one aspect of this disclosure, the working electrode of a glucose monitoring probe includes a sensing layer containing carbon nanotubes. The carbon nanotubes' catalytic effect on glucose reactions reduces the operating voltage required for the working electrode to function properly, minimizing interference with the working electrode caused by the electrochemical reactions of electroactive substances at high voltages. This also improves the probe's sensitivity to glucose and extends its linear range of response, extending its service life.

[0011] In addition, in the working electrode of the glucose monitoring probe according to one aspect of the present disclosure, optionally, the mass percentage of the carbon nanotubes in the sensing layer reagent is 1 to 50%, thereby enabling the metal polymer in the sensing layer reagent to more easily form covalent bonds with the carbon nanotubes.

[0012] In addition, in the working electrode of the glucose monitoring probe according to one aspect of the present disclosure, the semipermeable membrane optionally includes a diffusion control layer for controlling the diffusion of glucose molecules. In this case, the semipermeable membrane is blocked from glucose components in tissue fluid or blood, thereby preventing excessive glucose molecules from reacting with the working electrode and thus reducing the lifespan of the glucose monitoring probe.

[0013] In addition, in the working electrode of the glucose monitoring probe according to one aspect of the present disclosure, the semipermeable membrane may optionally include an anti-interference layer that blocks non-glucose substances. In this case, other components in tissue fluid or blood are blocked from entering the semipermeable membrane, thereby preventing other electroactive substances that can also generate current from affecting the working electrode and causing inaccurate glucose test results.

[0014] In addition, in the working electrode of the glucose monitoring probe according to one aspect of the present disclosure, optionally, the thickness of the sensing layer is 0.1 μm to 100 μm, thereby providing sufficient glucose enzyme under the premise of sufficient reaction and firm attachment.

[0015] Another aspect of the present disclosure provides a glucose monitoring probe, characterized in that it includes a working electrode, a counter electrode and a reference electrode arranged in a dispersed manner, the working electrode comprising: a base layer, which is arranged on a flexible substrate; a sensing layer, which is formed on the base layer by coating a sensing layer reagent, and can chemically react with glucose in blood or tissue fluid, the sensing layer reagent including a redox polymer, glucase, carbon nanotubes and a cross-linking agent, the carbon nanotubes adsorbing the redox polymer and the glucase, and adding amino modifications to the carbon nanotubes so that the redox polymer and the carbon nanotubes are tightly covalently bonded and combined with the glucase; a semipermeable membrane formed on the sensing layer, the semipermeable membrane including an anti-interference layer for blocking non-glucose substances and a diffusion control layer for controlling the diffusion of glucose molecules; and a biocompatible membrane formed on the semipermeable membrane.

[0016] In another aspect of the present disclosure, a glucose monitoring probe includes a redox polymer in its sensing layer. This reduces the operating voltage required for the working electrode to function properly, minimizing interference with the working electrode caused by the electrochemical reactions of electroactive substances at high voltages. This also improves the probe's sensitivity to glucose and increases its linear range of response, extending its service life.

[0017] In addition, in the working electrode of the glucose monitoring probe according to one aspect of the present disclosure, optionally, in the sensing layer reagent, the redox polymer is a metal redox polymer, thereby enabling the metal redox polymer to participate in the redox reaction.

[0018] In addition, in the working electrode of the glucose monitoring probe involved in one aspect of the present disclosure, optionally, the metal redox polymer can be selected from at least one of poly(vinylferrocene), quaternized poly(4-vinylpyridine) of ferricyanide, quaternized poly(1-vinylimidazole) of ferricyanide, quaternized poly(4-vinylpyridine) of ferrocyanide, quaternized poly(1-vinylimidazole) of ferrocyanide, osmium 2,2'-bipyridine complex coordinated to poly(1-vinylimidazole), osmium 2,2'-bipyridine complex coordinated to poly(4-vinylpyridine), cobalt 2,2'-bipyridine complex coordinated to poly(1-vinylimidazole) or cobalt 2,2'-bipyridine complex coordinated to poly(4-vinylpyridine). Thus, the metal redox polymer can participate in the redox reaction through covalent bonds, coordination bonds or ionic bonds.

[0019] Another aspect of the present disclosure provides a method for manufacturing a working electrode of a glucose monitoring probe, characterized in that it includes: preparing a flexible substrate; forming a base layer on the flexible substrate; preparing a sensing layer reagent including a redox polymer, glucose enzyme, carbon nanotubes and a cross-linking agent; coating the sensing layer reagent on the base layer to form a sensing layer; forming a semipermeable membrane on the sensing layer to control the passage rate of glucose molecules; and forming a biocompatible membrane on the semipermeable membrane.

[0020] In another aspect of the present disclosure, carbon nanotubes are included in the sensing layer, thereby reducing the operating voltage of the working electrode, reducing interference from other factors, improving the probe's sensitivity to glucose, and increasing the linear range of the probe's response to glucose, thereby extending the probe's service life.

[0021] In addition, in the method for manufacturing the working electrode of the glucose monitoring probe of the present disclosure, optionally, in the sensing layer reagent, the mass percentage of the carbon nanotubes is 1 to 50%, thereby better promoting the reaction of glucose enzyme.

[0022] According to the present disclosure, a working electrode of a glucose monitoring probe and a method for manufacturing the same can be provided, which can extend the service life of the probe, reduce interference, and improve the sensitivity to glucose. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram showing the usage state of the glucose monitoring probe involved in the embodiment of the present disclosure.

[0024] Figure 2 Schematic diagram showing the structure of a glucose monitoring probe according to an embodiment of the present disclosure.

[0025] Figure 3 It shows Figure 2 Schematic diagram of the structure of the glucose monitoring probe involved in a bent state.

[0026] Figure 4 Schematic diagram showing the structure of a working electrode of a glucose monitoring probe according to an embodiment of the present disclosure.

[0027] Figure 5 Schematic diagram showing glucose enzyme adsorbed on carbon nanotubes of a glucose monitoring probe according to an embodiment of the present disclosure.

[0028] Figure 6 FIG. 4 is a schematic diagram illustrating a glucose reaction between a glucose monitoring probe and tissue according to an embodiment of the present disclosure.

[0029] Figure 7 Schematic diagram showing the structure of the semipermeable membrane of the working electrode of the glucose monitoring probe according to the embodiment of the present disclosure.

[0030] Figure 8 1 is a flowchart illustrating a method for manufacturing a working electrode of a glucose monitoring probe according to an embodiment of the present disclosure.

[0031] Figure 9 1 is a flow chart showing a method for fabricating a semipermeable membrane of a working electrode of a glucose monitoring probe according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. In the following description, identical components are assigned identical reference numerals, and duplicate descriptions are omitted. In addition, the accompanying drawings are merely schematic, and the proportions of the dimensions of the components and the shapes of the components may differ from the actual ones.

[0033] In addition, the subheadings and the like in the following description of this disclosure are not intended to limit the content or scope of this disclosure, but are merely provided as a guide for reading. Such subheadings should not be understood as dividing the content of the article, nor should the content under the subheading be limited to the scope of the subheading.

[0034] Figure 1 Schematic diagram showing the usage state of the glucose monitoring probe involved in the embodiment of the present disclosure. Figure 2 FIG. 2 is a diagram showing the structure of a glucose monitoring probe according to an embodiment of the present disclosure. Figure 3 It shows Figure 2 Schematic diagram of the structure of the glucose monitoring probe involved in a bent state.

[0035] In this embodiment, the glucose monitoring probe 1 may sometimes also be referred to as an implantable glucose monitoring probe 1 , a glucose monitor probe 1 , or a probe 1 .

[0036] In this embodiment, the portable glucose monitor G may include a glucose monitoring probe 1 and an electronic system 2 connected to the glucose monitoring probe 1. By implanting the glucose monitoring probe 1 of the portable glucose monitor G into a human body, such as a body surface, the glucose monitoring probe 1 comes into contact with tissue fluid or blood on the body surface, thereby enabling the glucose monitoring probe 1 to sense a sensing signal related to glucose concentration in the tissue fluid. By transmitting the glucose concentration signal to the electronic system 2, the corresponding glucose concentration can be obtained.

[0037] Specifically, a portion of the glucose monitoring probe 1 (especially the sensing portion) can be implanted on the surface of the human body, for example, and in contact with the tissue fluid in the body. In addition, another portion of the glucose monitoring probe 1 is also connected to an electronic system 2 located outside the body surface. When the portable glucose monitor G is working, the glucose monitoring probe 1 reacts with the tissue fluid or blood in the body to generate a sensing signal (such as a current signal), and transmits the sensing signal to the electronic system 2 on the body surface. The electronic system 2 processes the sensing signal to obtain the glucose concentration. Although Figure 1 The glucose monitoring probe 1 is shown as being arranged on the arm, but the present embodiment is not limited thereto. For example, the glucose monitoring probe 1 may be arranged on the abdomen, waist, leg, etc.

[0038] In addition, in this embodiment, the glucose monitoring probe 1 can directly detect blood glucose or interstitial fluid glucose. In addition, the interstitial fluid glucose concentration is strongly correlated with the blood glucose concentration, and the blood glucose concentration can also be obtained from the interstitial fluid glucose.

[0039] In this embodiment, the glucose monitoring probe 1 may include a substrate S, and a working electrode 10, a reference electrode 20, and a counter electrode 30 (see Figure 2 ). In addition, the glucose monitoring probe 1 also includes a contact 41 connected to the working electrode 10 via a lead, a contact 42 connected to the reference electrode 20 via a lead, and a contact 43 connected to the counter electrode 30 via a lead. Contacts 41, 42, and 43 are all electrical contacts. In some examples, the glucose monitoring probe 1 can be connected to the electronic system 2 via contacts 41, 42, and 43.

[0040] In some examples, the substrate S may be a flexible substrate. The flexible substrate may be generally made of at least one of polyethylene (PE), polypropylene (PP), polyimide (PI), polystyrene (PS), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). Furthermore, in other examples, the flexible substrate may also be generally made of metal foil, ultra-thin glass, a single-layer inorganic film, multiple organic films, or multiple inorganic films.

[0041] In some examples, the substrate S may also be a non-flexible substrate. The non-flexible substrate may generally include ceramics, aluminum oxide, or silicon dioxide, which have relatively weak electrical conductivity. In this case, the glucose monitoring probe 1 having a non-flexible substrate may also have a sharp point or edge, thereby enabling the glucose monitoring probe 1 to be implanted on the body surface (e.g., the superficial layer of the skin, etc.) without the need for an auxiliary implant device (not shown).

[0042] In this embodiment, for the convenience of description, the glucose monitoring probe 1 can be divided into a connecting portion 1a and an implanting portion 1b (see Figure 3 ). Figure 3 The straight line AA' in FIG. 1 roughly shows the approximate position of the skin when the glucose monitoring probe 1 is implanted into the body surface, the connecting portion 1a is located outside the body surface, and the implantation portion 1b is implanted inside the body surface.

[0043] In addition, in some examples, the connection portion 1a and the implant portion 1b may both include a flexible substrate, but the present embodiment is not limited thereto. For example, only the implant portion 1b may include a flexible substrate, while the connection portion 1a includes a non-flexible substrate such as a rigid substrate.

[0044] In this embodiment, the implant portion 1b of the glucose monitoring probe 1 can be provided on an auxiliary puncture needle (not shown), and the implant portion 1b can be separated from the puncture needle. Specifically, the puncture needle can be inserted into tissue (e.g., the superficial layer of the skin), and then the puncture needle can be pulled out and separated from the implant portion 1b of the glucose monitoring probe 1, thereby leaving the implant portion 1b in the superficial layer of the skin and allowing the electronic system 2 to adhere to the skin surface. The connecting portion 1a of the glucose monitoring probe 1 (see FIG. 1 ) can be removed. Figure 3 ) is connected to the electronic system 2 and is located on the skin surface. Here, the electronic system 2 can be adhered to the skin surface by an adhesive provided on the substrate S.

[0045] In some examples, the puncture needle used to assist with implantation can have a notch, with the implant portion 1b placed within the notch. The puncture needle can be made of stainless steel. In this case, the needle's use risk is reduced, and it possesses sufficient hardness for easy skin puncture, making it easier for the patient to use. Additionally, in some examples, the puncture needle can be made of plastic, glass, or metal.

[0046] In this embodiment, an auxiliary implant device (not shown) such as a needle aid can be used to insert the puncture needle into the skin. In this case, the puncture depth can be pre-configured using, for example, a needle aid, and the user's pain can be reduced by using the needle aid to achieve quick and painless puncture. In addition, the auxiliary implant device can also facilitate one-handed operation. However, this embodiment is not limited to this. For example, as described above, when the glucose monitoring probe 1 is a rigid substrate, the glucose monitoring probe 1 can be implanted in the skin without the aid of a puncture needle.

[0047] In this embodiment, the depth of subcutaneous implantation of the glucose monitoring probe 1 is determined according to the desired location. When the fat layer is thick, the implantation depth is deeper, such as in the abdomen, where the implantation depth can be approximately 10 mm to 15 mm. When the fat layer is thin, the implantation depth is shallower, such as in the arm, where the implantation depth can be approximately 5 mm to 10 mm.

[0048] Figure 4 1 is a schematic structural diagram showing the working electrode 10 of the glucose monitoring probe 1 according to an embodiment of the present disclosure. Figure 5 Schematic diagram showing glucose enzyme adsorbed on carbon nanotubes of the glucose monitoring probe 1 according to an embodiment of the present disclosure. Figure 6 Schematic diagram showing the glucose reaction between the glucose monitoring probe 1 and tissue according to an embodiment of the present disclosure. Figure 7 Schematic diagram showing the structure of the semipermeable membrane of the working electrode 10 of the glucose monitoring probe 1 according to an embodiment of the present disclosure.

[0049] In this embodiment, as described above, the implantable portion 1b of the glucose monitoring probe 1 includes the working electrode 10 (see Figure 2 and Figure 3 ).

[0050] In this embodiment, in some examples, the working electrode 10 may include a base layer 110, a sensing layer 120, a semipermeable membrane 130, and a biocompatible membrane 140 (see Figure 4 In some examples, the base layer 110 , the sensing layer 120 , the semipermeable membrane 130 , and the biocompatible membrane 140 may be stacked in sequence.

[0051] In this embodiment, the base layer 110 is conductive. In some examples, the base layer 110 can be made of at least one selected from gold, glassy carbon, graphite, silver, silver chloride, palladium, titanium, and iridium. In this case, the base layer 110 can have good conductivity and can suppress electrochemical reactions in the base layer 110, thereby improving the stability of the base layer 110.

[0052] In this embodiment, in some examples, the base layer 110 can be disposed on the substrate S by a deposition or plating method. In some examples, the deposition method can include physical vapor deposition, chemical vapor deposition, etc. The plating method can include electroplating, chemical plating, vacuum plating, etc. In addition, in some examples, the base layer 110 can also be disposed on the substrate S by screen printing, extrusion, or electrolytic deposition.

[0053] In this embodiment, the base layer 110 can be provided on a flexible substrate. In this case, the flexible substrate makes the entire product lightweight, has strong impact resistance, and reduces the foreign body sensation after implantation. In other examples, the base layer 110 can also be provided on a rigid substrate.

[0054] In this embodiment, the sensing layer 120 can be formed on the base layer 110 by coating a sensing layer reagent, thereby being capable of chemically reacting with glucose. In some examples, the sensing layer reagent may include a redox polymer, a glucose enzyme, carbon nanotubes 121, and a crosslinking agent. In this case, the sensing layer 120 includes carbon nanotubes 121. The catalytic effect of the carbon nanotubes 121 on the glucose reaction reduces the operating voltage required for the working electrode 10 to function properly, thereby reducing interference with the working electrode 10 caused by the electrochemical reaction of electroactive substances at high voltages and the generation of current.

[0055] In some examples, the redox polymer may have a covalent bond, a coordination bond, or an ionic bond. In some examples, the redox polymer may be a metal polymer that performs a redox function, i.e., a metal redox polymer. The metal polymer here may, for example, be a metal polymer containing a covalent bond, a coordination bond, or an ionic bond. In some examples, the metal polymer may be selected from at least one of poly(vinylferrocene), quaternized poly(4-vinylpyridine) of ferrocyanide, quaternized poly(1-vinylimidazole) of ferrocyanide, quaternized poly(4-vinylpyridine) of ferrocyanide, quaternized poly(1-vinylimidazole) of ferrocyanide, osmium 2,2'-bipyridine complex coordinated to poly(1-vinylimidazole), osmium 2,2'-bipyridine complex coordinated to poly(4-vinylpyridine), cobalt 2,2'-bipyridine complex coordinated to poly(1-vinylimidazole), or cobalt 2,2'-bipyridine complex coordinated to poly(4-vinylpyridine).

[0056] Generally speaking, carbon nanotubes are mainly composed of several to dozens of layers of coaxial circular tubes of carbon atoms arranged in a hexagonal pattern. The distance between layers is fixed, about 0.34 nm, and the diameter is generally 2 to 20 nm.

[0057] In some examples, such as Figure 5As shown, the carbon nanotubes 121 can be in the shape of a hollow column. Specifically, the carbon nanotubes 121 can be in the shape of a cylinder or an elliptical cylinder. In addition, due to their large surface area and surface hydrophobicity, the carbon nanotubes 121 have a strong adsorption capacity for organic matter.

[0058] In the sensing layer 120 , since the carbon nanotubes 121 can adsorb glucose enzymes and redox polymers (such as metal polymers), the carbon nanotubes 121 can fully contact and catalyze the reaction during the glucose reaction, thereby more effectively promoting the glucose reaction.

[0059] In this embodiment, the carbon nanotubes 121 can be dissolved in a solvent and added to the sensing layer reagent, thereby facilitating the preparation of the sensing layer 120 containing the carbon nanotubes 121 .

[0060] In some examples, the mass percentage of carbon nanotubes 121 in the sensing layer reagent can be 1 to 50%. This can better promote the reaction of glucose enzymes. In some examples, to better match the coating process, the mass percentage of carbon nanotubes 121 can be 5 to 10%. This can ensure the effectiveness of the sensing layer reagent while also promoting the corresponding effect. Specifically, the mass percentage of carbon nanotubes 121 can be 5%, 6%, 7%, 8%, 9%, or 10%.

[0061] In some examples, the sensing layer reagent can be formed into the sensing layer 120 by at least one process such as spin coating, dip coating, drop coating, or spray coating.

[0062] In this embodiment, the sensing layer 120 may be a glucose oxidase sensing layer or a glucose dehydrogenase sensing layer.

[0063] The following, combined Figure 6 , glucose oxidase (GO X (FAD) and redox polymer (MED red ) as an example to illustrate the reaction occurring in the glucose sensing layer 120.

[0064] For example, after the working electrode 10 is implanted subcutaneously (e.g., subcutaneously in the arm), the glucose sensing layer 120 in the working electrode 10 contacts the tissue fluid in the body. X When FAD encounters glucose in tissues, the following reactions occur:

[0065] Glucose + GOx(FAD) → Gluconolactone + GOx(FADH2) ... Reaction formula (I)

[0066] GOx(FADH2)+MED ox →GOx(FAD)+MEDred ...Reaction formula (II)

[0067] MED red -e - →MED ox ...Reaction formula (III)

[0068] In the above reaction process, it can be seen that the oxidation state of the redox polymer (MED ox ) is restored to MED red , MED red Oxidized to MED by applying working voltage ox , however, if MED red Cannot be rapidly oxidized to MED ox , causing MED ox The lack of reaction formula (II) and reaction formula (I) limits the reaction rate to MED ox The amount of glucose will slow down the reaction with tissue glucose, causing the glucose monitoring probe 1 to fail. Therefore, by adding carbon nanotubes 121 to the sensing layer 120, the carbon nanotubes 121 can greatly accelerate the MED under the action of catalysts, and at a lower voltage. red Oxidized to MED ox .

[0069] Through the above-mentioned reaction formulas (I) to (III), the reaction with tissue glucose can be sustained. In addition, the use of carbon nanotubes 121 can accelerate the progress of reaction (III) and reduce the voltage required to be applied during the reaction, thereby facilitating the improvement of the sensitivity of the glucose monitoring probe 1, extending the service life of the glucose monitoring probe 1, and obtaining a low operating voltage. In other words, through the carbon nanotubes 121, a high-sensitivity tissue glucose sensing signal can be continuously obtained, extending the service life of the glucose monitoring probe 1, while the low operating voltage helps improve the anti-interference performance.

[0070] In some examples, the carbon nanotubes 121 in the sensing layer reagent can also be modified with amino groups. This allows for a tight covalent bond between the metal polymer and the carbon nanotubes 121, thereby enabling more stable binding to the glucase. Furthermore, the addition of amino groups to the carbon nanotubes 121 can also allow for a tight covalent bond between the redox polymer and the carbon nanotubes 121.

[0071] In other examples, graphene, porous titanium dioxide, or conductive organic salts may be added to the sensing layer reagent to better promote the reaction of glucose enzyme.

[0072] In this embodiment, the glucose monitoring probe 1 is implanted in the human skin to continuously sample the glucose in the blood, convert it into a corresponding current signal, and transmit it to the electronic system 2 outside the body.

[0073] In this embodiment, the thickness of the sensing layer 120 can be approximately 0.1 μm to 100 μm, preferably approximately 2 μm to 10 μm. In one example, the thickness of the sensing layer 120 can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. In this case, by controlling the thickness of the glucose oxidase or dehydrogenase within a certain range, the problem of excessive glucose oxidase or dehydrogenase causing a decrease in adhesion and causing the material to fall off in the body is avoided, and the problem of insufficient glucose oxidase or dehydrogenase causing an insufficient reaction and an inability to feedback normal glucose concentration information is avoided.

[0074] In this embodiment, if Figure 4 and Figure 7 As shown, the semi-permeable membrane 130 may be distributed on the sensing layer 120 , that is, the semi-permeable membrane 130 may be disposed on the sensing layer 120 .

[0075] In addition, in this embodiment, Figure 7 As shown, the semipermeable membrane 130 may include a diffusion control layer 131 and an anti-interference layer 132 stacked on the diffusion control layer 131. In the semipermeable membrane 130, the diffusion control layer 131 can control the diffusion of glucose molecules, and the anti-interference layer 132 can block the diffusion of non-glucose substances. In this way, the tissue fluid or blood components passing through the semipermeable membrane 130 can be reduced first, and then the anti-interference layer 132 can block the interference outside the semipermeable membrane 130. Common interferences may include uric acid, ascorbic acid, acetaminophen, etc. that are commonly present in the body.

[0076] In other examples, not limited to Figure 7 For example, in the semipermeable membrane 130, the diffusion control layer 131 can also be stacked on the anti-interference layer 132. In this case, the interference of impurities on the working electrode 10 can also be reduced, the accuracy of the detection results can be improved, and the service life of the glucose monitoring probe 1 can be extended.

[0077] In this embodiment, the semipermeable membrane 130 can control the rate of glucose molecules passing through it, that is, the semipermeable membrane 130 can limit the number of glucose molecules in the tissue fluid or blood that reach the sensing layer 120. Specifically, the diffusion control layer 131 of the semipermeable membrane 130 can effectively reduce the amount of glucose that diffuses into the sensing layer 120 by a certain ratio.

[0078] In this embodiment, the diffusion control layer 131 can reduce the rate of glucose entering the sensor layer 120 by 10 to 100 times, preferably by 30 to 80 times, for example, by 30, 40, 50, 60, 70, or 80 times. In this case, the amount of glucose diffusing into the sensor layer 120 can be reduced, ensuring sufficient glucose oxidase or dehydrogenase and other substances involved in the reaction. The glucose concentration becomes the primary factor limiting the electrode current, allowing the current to accurately reflect the glucose concentration. This also significantly increases the linear range of the glucose monitoring probe 1.

[0079] In this embodiment, the biocompatible membrane 140 may be disposed on the semipermeable membrane 130 (see Figure 4 ).

[0080] In some examples, the biocompatible membrane 140 can be made of plant materials. The plant materials can be sodium alginate, tragacanth gum, pectin, gum arabic, xanthan gum, guar gum, agar, or natural material derivatives. The natural material derivatives can include starch derivatives, cellulose derivatives, and the like.

[0081] In other examples, the biocompatible membrane 140 can also be made of synthetic materials. These synthetic materials can include polyolefins such as povidone, polyvinyl alcohol, polyisobutylene pressure-sensitive adhesive, and ethylene-vinyl acetate copolymer; polyacrylic acids such as acrylic resin, carboxyethylene-sucrose, carboxyethylene-pentaerythritol copolymer, and polyacrylate pressure-sensitive adhesive; and polyoxyethylenes such as polyoxyethylene fatty acid esters and polyoxyethylene-polyoxypropylene copolymers. Polyesters such as polylactic acid, polyglycolide-lactide, polydinonyl sebacate, polycyanoalkylamino ester, and polyether polyurethane can be used. This can suppress the body's immune response to the glucose monitoring probe 1 and extend the life of the glucose monitoring probe 1.

[0082] In addition, in some examples, the semipermeable membrane 130 may also be biocompatible, thereby omitting the biocompatible membrane 140 and reducing manufacturing costs.

[0083] In other examples, modifiers can be used to adjust the permeability of the formed membrane to the analyte of interest. For example, hydrophilic modifiers include polyethylene glycol, hydroxyl, or polyhydroxyl modifiers. This can increase the biocompatibility of the polymer-formed membrane, thereby replacing biocompatible membrane 140.

[0084] In this embodiment, the biocompatible film 140 may cover the entire glucose monitoring probe 1. In some examples, the biocompatible film 140 may only cover the implanted portion 1b of the glucose monitoring probe 1, thereby reducing the use of raw materials.

[0085] In this embodiment, the glucose monitoring probe 1 can be used for a period of 1 to 24 days, preferably 7 to 14 days. Furthermore, as described above, the semipermeable membrane 130 can restrict the entry of some glucose molecules and electroactive interfering substances, effectively expanding the linear range of the glucose monitoring probe 1. Furthermore, the sensing layer 120 can better react with glucose oxidase or dehydrogenase, thereby maintaining a stable usage period for the glucose monitoring probe 1.

[0086] In addition, the glucose monitoring probe 1 can also be used in common detection, such as single detection or short-term monitoring. For example, the monitoring time can be 1 hour to 24 hours or 24 hours to 36 hours.

[0087] In addition, the addition of the biocompatible membrane 140 can maintain the service life of the glucose monitoring probe 1 at 1 day to 24 days, for example, it can be 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, 21 days, 22 days, 23 days, and 24 days. This makes it convenient for users to choose a glucose monitor G with glucose monitoring probes 1 with different service lives according to different needs (such as price, etc.).

[0088] In this embodiment, as described above, the glucose monitoring probe 1 may further include a reference electrode 20 and a counter electrode 30 (see Figure 2 ). Specifically, Figure 3 As shown, the implant portion 1 b of the glucose monitoring probe 1 may include a reference electrode 20 and a counter electrode 30 .

[0089] In this embodiment, after being implanted in the skin, the glucose monitoring probe 1 can generate a current signal by performing an oxidation-reduction reaction between the glucose oxidase or dehydrogenase in the working electrode 10 and the glucose in the tissue fluid or blood, and forming a loop with the counter electrode 30 .

[0090] In this embodiment, reference electrode 20 can form a known and fixed potential difference with tissue fluid or blood. In this case, the potential difference between working electrode 10 and tissue fluid or blood can be measured using the potential difference between reference electrode 20 and working electrode 10, thereby accurately determining the voltage generated by working electrode 10. Consequently, electronic system 2 can automatically adjust and maintain the voltage at working electrode 10 according to a pre-set voltage value, ensuring that the measured current signal accurately reflects the glucose concentration value.

[0091] In addition, in this embodiment, the working electrode 10, the reference electrode 20 and the counter electrode 30 of the implant part 1b are arranged in a dispersed manner, but the embodiments of the present disclosure are not limited thereto and may also include a side-by-side (parallel) arrangement.

[0092] In addition, in this embodiment, the glucose monitoring probe 1 is not limited to a planar probe, but may also be a linear probe, a probe having stacked electrodes or layered electrodes, or a probe having coplanar electrodes in which electrodes are arranged on the same plane.

[0093] In some examples, when the potential difference between the working electrode 10 and the tissue fluid or blood does not fluctuate much, the reference electrode 20 may not be used.

[0094] In this embodiment, the counter electrode 30 can be made of platinum, silver, silver chloride, palladium, titanium, or iridium. Thus, it can be made without affecting the electrochemical reaction at the working electrode 10 while having good electrical conductivity. However, this embodiment is not limited thereto. In other examples, the counter electrode 30 can also be made of at least one selected from gold, glassy carbon, graphite, silver, silver chloride, palladium, titanium, or iridium. Thus, it can be made with good electrical conductivity while reducing the impact on the working electrode 10.

[0095] Additionally, in some examples, the working electrode 10 , the counter electrode 30 , and the reference electrode 20 may be made of the same material.

[0096] In addition, in this embodiment, the glucose monitoring probe 1 may include two, three, or more electrodes. For example, the glucose monitoring probe 1 may include only two electrodes: a working electrode 10 and a counter electrode 30. Furthermore, the glucose monitoring probe 1 may include an additional reference electrode in addition to the working electrode 10, the reference electrode 20, and the counter electrode 30. In this case, the potential difference of the working electrode 10 and the voltage of the working electrode 10 can be more accurately determined, thereby obtaining a more accurate current.

[0097] In this embodiment, as described above, the connection portion 1a of the glucose monitoring probe 1 includes a plurality of contacts (contacts). The number of contacts is equal to the number of electrodes in the implant portion 1b of the glucose monitoring probe 1. Leads (wires) connect the contacts to the electrodes in the implant portion 1b.

[0098] In this embodiment, if Figure 3 As shown, the implant portion 1b of the glucose monitoring probe 1 has three electrodes. Accordingly, the connecting portion 1a includes three contacts (contact heads), namely, contact 41, contact 42, and contact 43. However, this embodiment is not limited thereto. For example, the implant portion 1b may have two or more electrodes, and accordingly, the connecting portion 1a may include two or more contacts (contact heads).

[0099] In this embodiment, contacts 41, 42, and 43 may all be disc-shaped, for example, they may be formed as solder pads. Alternatively, contacts 41, 42, and 43 may be formed as solder joints. In other examples, contacts 41, 42, and 43 may also be rectangular, elliptical, or other irregular shapes.

[0100] In this embodiment, the current signal generated by the implantable portion 1b of the glucose monitoring probe 1 is transmitted via the base layer 110 and the transmission wires to the contacts of the connecting portion 1a. Specifically, the implantable portion 1b of the glucose monitoring probe 1 is connected to the connecting portion 1a, which is in turn connected to the electronic system 2 via multiple contacts. Therefore, the current signal generated by the working electrode 10 is transmitted via the contacts of the connecting portion 1a to the electronic system 2 for analysis. The electronic system 2 then analyzes and processes the current signal to obtain a glucose concentration signal.

[0101] In addition, in some examples, the electronic system 2 can be transmitted to an external reading device via wireless communication methods such as Bluetooth, WiFi, etc. The reading device (not shown) can receive the glucose concentration signal emitted by the electronic system 2 and display the glucose concentration value. In addition, the glucose monitoring probe 1 involved in this embodiment can achieve continuous monitoring, thereby achieving the purpose of continuously monitoring the glucose concentration value of the human body for a long time (for example, 1 day to 24 days). In addition, in some examples, the reading device can be a reader or a mobile phone APP.

[0102] Furthermore, in this embodiment, the glucose monitoring probe 1 and electronic system 2 do not require calibration during in vivo use. Furthermore, the glucose monitoring probe 1 and electronic system 2 can be pre-calibrated at the factory. This eliminates the need for users to regularly calibrate the monitoring system using fingerstick blood tests and reduces potential sources of error in monitoring module readings during use.

[0103] In this embodiment, the electronic system 2 can be made of a flexible PCB and a flexible battery. This allows it to fit snugly against the skin, minimizing impact on the user's daily life. In some examples, the electronic system 2 can be circular in shape. Furthermore, in some examples, the electronic system 2 can include a waterproof housing and a waterproof bandage, allowing the user to use it without affecting daily activities such as swimming or bathing.

[0104] In this embodiment, the glucose monitoring probe 1 can obtain the glucose concentration in tissue fluid or blood. However, this embodiment is not limited to this. For example, by changing the sensing layer 120 on the glucose monitoring probe 1, data of other body fluid components besides glucose can also be obtained. The body fluid components here can include, for example, acetylcholine, amylase, bilirubin, cholesterol, human chorionic gonadotropin, creatine kinase, creatine, creatinine, DNA, fructosamine, glucose, glutamine, growth hormone, hormones, ketone bodies, lactate, oxygen, peroxide, prostate-specific antigen, prothrombin, RNA, thyroid-stimulating hormone, and troponin.

[0105] In other examples, the concentration of drugs in body fluids may also be monitored, such as antibiotics (eg, gentamicin, vancomycin, etc.), digitoxin, digoxin, theophylline, and warfarin, etc.

[0106] In this embodiment, a sensing layer 120 is first formed on the base layer 110 of the working electrode 10, a semipermeable membrane 130 is then formed on the sensing layer 120, and finally a biocompatible membrane 140 is formed on the semipermeable membrane 130. This extends the service life of the glucose monitoring probe 1, reduces interference from other factors, and improves the glucose monitoring probe's 1 response speed to glucose.

[0107] Hereinafter, a method for manufacturing the working electrode 10 of the glucose monitoring probe 1 will be described in detail with reference to the accompanying drawings.

[0108] Figure 8 1 is a flowchart illustrating a method for manufacturing the working electrode 10 of the glucose monitoring probe 1 according to an embodiment of the present disclosure. Figure 9 1 is a flowchart illustrating a method for manufacturing the semipermeable membrane 130 of the working electrode 10 of the glucose monitoring probe 1 according to an embodiment of the present disclosure.

[0109] In this embodiment, the method for making the working electrode 10 of the glucose monitoring probe 1 may include (see Figure 8): Prepare a flexible substrate and form a base layer 110 on the flexible substrate (step S110); prepare a sensing layer 120 reagent including a redox polymer, glucose enzyme, carbon nanotubes 121 and a cross-linking agent (step S120); coat the sensing layer reagent on the base layer 110 and form the sensing layer 120 (step S130); form a semipermeable membrane 130 for controlling the passing rate of glucose molecules on the sensing layer 120 (step S140); and form a biocompatible membrane 140 on the semipermeable membrane 130 (step S150). In this case, the carbon nanotubes 121 are included in the sensing layer 120. As a result, the working voltage of the working electrode 10 is reduced, the interference of other factors is reduced, and the sensitivity of the probe to glucose is improved. It can also increase the linear range of the glucose monitoring probe 1's response to glucose and extend the service life of the probe.

[0110] As described above, in step S110, a flexible substrate is prepared and a base layer 110 is formed on the flexible substrate. In some examples, the base layer 110 can also be formed by one or more of electroplating, evaporation, printing, or extrusion.

[0111] In this embodiment, in some examples, in step S130 , the sensing layer 120 may be a glucose oxidase sensing layer or a glucose dehydrogenase sensing layer.

[0112] In some examples, in step S110, the redox polymer may have a covalent bond, a coordination bond, or an ionic bond. In some examples, the redox polymer may be a metal polymer that performs a redox function. The metal polymer here may, for example, be a metal polymer containing a covalent bond, a coordination bond, or an ionic bond. In some examples, the metal polymer may be selected from at least one of poly(vinylferrocene), quaternized poly(4-vinylpyridine) of ferrocyanide, quaternized poly(1-vinylimidazole) of ferrocyanide, quaternized poly(4-vinylpyridine) of ferrocyanide, quaternized poly(1-vinylimidazole) of ferrocyanide, osmium 2,2'-bipyridine complex coordinated to poly(1-vinylimidazole), osmium 2,2'-bipyridine complex coordinated to poly(4-vinylpyridine), cobalt 2,2'-bipyridine complex coordinated to poly(1-vinylimidazole), or cobalt 2,2'-bipyridine complex coordinated to poly(4-vinylpyridine).

[0113] In the manufacturing method involved in this embodiment, as Figure 9As shown, step S140 may include first forming an anti-interference layer 132 on the sensing layer 120 (step S141), and then forming a diffusion control layer 131 on the anti-interference layer (step S142). In this way, the anti-interference layer 132 can first reduce the amount of tissue fluid or blood components passing through the semi-permeable membrane 130, and then the diffusion control layer 131 can block the interference outside the semi-permeable membrane 130.

[0114] In some examples, in step S140, the order of step S141 and step S142 can be interchanged. That is, the diffusion control layer 131 can be first formed on the glucose oxidase or dehydrogenase layer (step S142), and then the anti-interference layer 132 can be formed on the diffusion control layer 131 (step S141). This can also reduce the interference of impurities on the working electrode 10, prevent inaccurate detection results, and extend the service life of the glucose monitoring probe 1.

[0115] Although the present disclosure has been described in detail above with reference to the accompanying drawings and embodiments, it will be understood that the above description does not limit the present disclosure in any form. Those skilled in the art may modify and change the present disclosure as needed without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope of the present disclosure.

Claims

1. A working electrode of a glucose monitoring probe with reduced interference, characterized in that: Including base layer, sensing layer, semipermeable membrane and biocompatible membrane, The base layer is provided on a flexible substrate; The sensing layer is formed on the base layer by coating a sensing layer reagent, which is capable of chemically reacting with glucose in blood or tissue fluid. The sensing layer reagent includes a redox polymer, a glucose enzyme, carbon nanotubes, and a cross-linking agent. The carbon nanotubes are modified with amino groups so that the redox polymer and the carbon nanotubes are tightly covalently bonded and combined with the glucose enzyme. Under the catalytic action of the carbon nanotubes, the working voltage required for the working electrode is reduced. The glucose enzyme is glucose oxidase. The semipermeable membrane is formed on the sensing layer to control the passing rate of glucose molecules; The biocompatible membrane is formed on the semipermeable membrane.

2. The working electrode according to claim 1, characterized in that In the sensing layer reagent, the mass fraction of the carbon nanotubes is 5% to 10%.

3. The working electrode according to claim 1, characterized in that The carbon nanotubes are in the shape of hollow columns.

4. The working electrode according to claim 1, characterized in that The semipermeable membrane includes a diffusion control layer for controlling the diffusion of glucose molecules and an anti-interference layer for blocking non-glucose substances.

5. The working electrode according to claim 4, characterized in that The anti-interference layer is formed on the sensing layer, and the diffusion control layer is formed on the anti-interference layer; or The diffusion control layer is formed on the sensing layer, and the anti-interference layer is formed on the diffusion control layer.

6. The working electrode according to claim 4, characterized in that The diffusion control layer reduces ingress by a factor of 10 to 100.

7. The working electrode according to claim 1, characterized in that The redox polymer has covalent bonds, coordinate bonds or ionic bonds.

8. The working electrode according to claim 1, characterized in that The base layer is made of at least one selected from the group consisting of gold, glassy carbon, graphite, silver, silver chloride, palladium, titanium, and iridium.

9. The working electrode according to claim 1, characterized in that The sensing layer reagent further comprises graphene, porous titanium dioxide or conductive organic salt.

10. The working electrode according to claim 1, characterized in that The thickness of the sensing layer is 2 μm to 10 μm.

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