Interstitial fluid glucose detection device based on porous microneedle array

Abstract

The invention relates to the field of medical instruments, and particularly discloses an interstitial fluid glucose detection device based on a porous microneedle array, which comprises a microneedle module, a colorimetric detection module, an electrochemical detection module and a liquid guide layer, the porosity is gradually increased in the direction from the needle tip to the microneedle substrate; the porous microneedle array pierces the epidermis of a human body and draws interstitial fluid, and the interstitial fluid is transferred to the colorimetric detection module and the electrochemical detection module through the liquid guide layer; in the colorimetric detection module, glucose reacts and develops color on a colorimetric film, so that rapid detection of glucose is realized; in the electrochemical detection module, glucose is subjected to an oxidation-reduction reaction on a working electrode to generate a current signal, so that accurate detection of glucose is realized. The device is simple in structure and convenient to operate, skin puncture is achieved in a minimally invasive and low-pain mode, and the interstitial fluid glucose concentration can be rapidly and accurately detected.

Description

Technical Field

[0001] The present application relates to the field of medical devices, and in particular to an interstitial fluid glucose detection device based on a porous microneedle array. Background Art

[0002] As the number of current diabetic patients and early-stage groups increases year by year, accurate detection of blood sugar levels is of great significance for patients to manage their own health and receive timely treatment. Although the traditional fingertip blood test has good accuracy, its operation is cumbersome and accompanied by considerable pain. Therefore, it is of great significance to develop a blood sugar detection technology that is accurate, simple, convenient, minimally invasive and painless.

[0003] Interstitial fluid is an extracellular fluid that is located between cells and intravascular fluid, filling the intercellular spaces of tissues. It is one of the important liquid environments for maintaining normal cell function. Interstitial fluid contains biomarkers such as glucose, and exchanges substances with plasma through tiny pores in the capillary walls, making the concentrations of these markers in the interstitial fluid strongly correlated with their concentrations in the blood, thus having potential value for bioinformatics analysis. Therefore, it has become a feasible solution to indirectly detect blood sugar concentration by detecting the concentration of glucose in the interstitial fluid.

[0004] With the rapid development of micro-nano processing technology, porous microneedle arrays, as a new type of minimally invasive transdermal device, have shown unique advantages in the field of biosensing, especially in the extraction of skin interstitial fluid, and have potential important application value. Summary of the invention

[0005] In order to improve the problem that the current conventional blood glucose testing is complicated and painful, the present application provides an interstitial fluid glucose detection device based on a porous microneedle array.

[0006] The present application provides an interstitial fluid glucose detection device based on a porous microneedle array, which adopts the following technical solution: An interstitial fluid glucose detection device based on a porous microneedle array, comprising: A microneedle module, comprising a porous microneedle array for piercing the human epidermis and drawing interstitial fluid, wherein the porous microneedle array comprises a microneedle substrate and a plurality of porous microneedles arrayed on the microneedle substrate, wherein the porous microneedles have a porosity gradient, and the porosity gradually increases from the needle tip to the microneedle substrate; A colorimetric detection module, comprising a colorimetric film for reacting with glucose in the interstitial fluid to develop color, wherein the depth of the developed color is related to the glucose concentration; An electrochemical detection module, comprising a flexible substrate and a three-electrode system disposed on the flexible substrate, wherein the three-electrode system comprises a counter electrode, a reference electrode and a working electrode, and glucose in the interstitial fluid undergoes an oxidation-reduction reaction on the working electrode and generates a current signal related to the glucose concentration; The liquid conducting layer is attached to the microneedle substrate and is used to transfer the interstitial fluid drawn by the porous microneedle array to the colorimetric detection module and the electrochemical detection module at the same time.

[0007] The porous microneedles in the porous microneedle array have a porosity gradient, and the porosity gradually increases from the needle tip to the microneedle base. The needle tip with a smaller porosity has a greater strength, and thus has a stronger puncture ability, which is conducive to reducing the pain of puncture; the needle body with a larger porosity has a good water absorption capacity to achieve rapid absorption of interstitial fluid, providing sufficient target for colorimetric detection and electrochemical detection.

[0008] The porous microneedle array absorbs interstitial fluid and transfers it to the colorimetric detection module and the electrochemical detection module through the fluid conducting layer. In the colorimetric detection module, the colorimetric film reacts with the glucose in the interstitial fluid to develop color, and the depth of the color is related to the glucose concentration, thereby realizing rapid detection of glucose concentration. In the electrochemical detection module, the glucose in the interstitial fluid undergoes an oxidation-reduction reaction on the working electrode and generates a current signal related to the glucose concentration, thereby realizing accurate detection of glucose concentration.

[0009] The detection device provided in the present application can perform both rapid and accurate detection of interstitial fluid glucose concentration. The colorimetric detection module and the electrochemical detection module can be used simultaneously or separately, and are suitable for different application scenarios. The colorimetric detection module is used in scenarios that require rapid detection, and the electrochemical detection module is used in scenarios that require accurate detection. This provides a convenient and accurate solution for assessing blood sugar levels for diabetic patients and people at risk.

[0010] Furthermore, the porous microneedle is in the shape of a quadrangular pyramid.

[0011] Compared with the conical type, the quadrangular pyramid needle tip is smaller and easier to pierce the skin. At the same time, the tip-guiding properties brought by its shape structure help guide the skin interstitial fluid to the microneedle base.

[0012] Furthermore, the porous microneedle has a micrometer-scale spatial network structure.

[0013] The porous structure obtained by the traditional porogen method usually has uneven pore distribution, which will form unstable points locally and easily collapse when subjected to stress; the pores of the porous microneedles provided in the present application are spatially network-connected, have good mechanical stability and good water absorption performance.

[0014] Furthermore, the method for preparing the porous microneedle array having a porosity gradient comprises the following steps: Positive mold preparation: Prepare the positive mold of the microneedle array by 3D printing; Negative mold preparation: Cover the negative mold material on the surface of the microneedle array positive mold, and obtain the microneedle array negative mold after demoulding; Solvent evaporation: The hexafluoroisopropanol solution of polyglycolide is injected into the negative mold of the microneedle array, and the hexafluoroisopropanol is directionally evaporated to obtain a porous microneedle array with a porosity gradient.

[0015] Furthermore, in the solvent volatilization step, the solvent at the needle body evaporates first, and the solvent at the needle tip evaporates later.

[0016] During the rapid volatilization of the hexafluoroisopropanol solvent, the polyglycolide-hexafluoroisopropanol solution gradually becomes saturated, especially at the solid-liquid-gas boundary, where a local high saturation area appears, and a small amount of polyglycolide is first precipitated to become the crystal nucleus. Subsequently, the polyglycolide component in the solution precipitates and grows around the crystal nucleus. Affected by the semi-crystalline characteristics of polyglycolide, the growth is non-directional and eventually presents the characteristics of a high-porosity spatial network structure. The higher the concentration of polyglycolide, the higher the supersaturation of the solution, resulting in an increase in the number of crystal nuclei in the solution and an increase in the precipitation rate of polyglycolide, but the volume of a single crystal region decreases, and the final spatial network structure has a low porosity.

[0017] In the solvent volatilization step of preparing the porous microneedle array, the solvent near the microneedle base evaporates first, and the solvent near the microneedle tip evaporates later, that is, the solvent evaporates in a directional manner; the closer to the microneedle tip, the slower the solvent evaporates and the higher the concentration of the residual polyglycolide-hexafluoroisopropanol solution, and the lower the porosity of the precipitated polyglycolide. In this way, by controlling the solvent volatilization direction, a porous microneedle array with a porosity gradient is prepared.

[0018] Furthermore, the colorimetric film is a TMB functionalized porous film on which glucose oxidase and horseradish peroxidase are fixed, and the colorimetric film is attached to the liquid-conducting layer.

[0019] During detection, the interstitial fluid diffuses in the colorimetric film, and glucose oxidase oxidizes the glucose in the interstitial fluid to produce hydrogen peroxide, which further reacts with TMB under the action of horseradish peroxidase to produce colored products. The higher the glucose concentration, the more colored products are produced and the darker the color. The glucose concentration can be detected according to the depth of the color.

[0020] Furthermore, the method for preparing the colorimetric film comprises the following steps: Dissolving TMB in a hexafluoroisopropanol solution of polyglycolide and spreading it on a substrate, allowing the hexafluoroisopropanol to evaporate, thereby obtaining a TMB-functionalized porous film; Glucose oxidase and horseradish peroxidase solutions were added dropwise to the TMB-functionalized porous film to obtain a colorimetric film.

[0021] During the evaporation of the solvent, polyglycolide and TMB are precipitated simultaneously, so that TMB can be evenly distributed and fixed in the spatial network structure of polyglycolide, significantly reducing the "coffee ring effect", which is beneficial to improving the color uniformity and stability of the colorimetric film.

[0022] Furthermore, the three-electrode system is coated with a hydrogel layer, and the hydrogel layer is attached to the liquid-conducting layer.

[0023] Furthermore, the working electrode comprises a conductive circuit in a cross-comb structure and a porous conductive carrier covering the conductive circuit, and the porous conductive carrier is loaded with glucose oxidase.

[0024] Furthermore, the porous conductive carrier is a porous particle of polyglycolide adsorbed with carbon nanotubes.

[0025] The glucose in the interstitial fluid reacts with the glucose oxidase in the working electrode to produce hydrogen peroxide. When a certain potential is applied externally, the hydrogen peroxide oxidizes and decomposes to produce electrons. The higher the glucose concentration, the more hydrogen peroxide is produced, that is, the more electrons, the greater the current generated. The glucose concentration in the interstitial fluid can be analyzed by detecting the magnitude of the current.

[0026] The conductive circuits with cross-comb structure increase the contact area between the test solution and the working electrode. The porous conductive carrier has a conductive three-dimensional structure with high specific surface area and good biocompatibility. It can increase the contact area of ​​the reaction while tightly fixing glucose oxidase and maintaining enzyme activity, thereby obtaining a larger detection current at the same test substance concentration, improving signal resolution and detection accuracy, and realizing high-sensitivity detection of glucose in interstitial fluid.

[0027] In summary, the present application includes at least one of the following beneficial technical effects: 1. The porous microneedles in the porous microneedle array provided in the present application have a micrometer-level spatial network structure and a porosity gradient, and the porosity gradually increases from the needle tip to the microneedle base; the needle tip with a smaller porosity has a greater strength, and thus has a stronger puncture ability; the needle body with a larger porosity has a good water-absorbing ability to achieve rapid absorption of interstitial fluid, providing sufficient target for colorimetric detection and electrochemical detection, which is conducive to improving detection efficiency; 2. The colorimetric detection module provided in this application uses the principle of color response change to determine the concentration of a specific substance by analyzing the degree of color change caused by the substance. It has high selectivity and sensitivity, can respond quickly to changes in the concentration of the target substance and perform accurate measurements, and is convenient for users to quickly obtain test results; 3. The electrochemical detection module circuit provided in the present application is manufactured using inkjet printing technology, which has a simple process and is easy to mass produce; the porous conductive carrier in the working electrode has a conductive three-dimensional structure with a high specific surface area and good biocompatibility, which can tightly fix glucose oxidase and maintain enzyme activity while increasing the contact area of ​​the reaction, obtaining a larger detection current at the same concentration of the analyte, improving signal resolution and detection accuracy, and realizing high-sensitivity detection of glucose in interstitial fluid; 4. The interstitial fluid glucose detection device based on a porous microneedle array provided in the present application has a simple structure and is easy to operate. It can puncture the skin minimally invasively and painlessly and realize in situ real-time detection. It can perform both rapid and accurate detection of interstitial fluid glucose concentration. The colorimetric detection module and the electrochemical detection module can be used simultaneously or separately, providing a convenient and accurate solution for assessing blood sugar levels for diabetic patients and risk groups, and can be applied to actual scenarios such as self-testing of blood sugar concentration by diabetic patients and rapid testing of blood sugar. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a side view of an interstitial fluid glucose detection device based on a porous microneedle array in an embodiment of the present application; Figure 2 is a top view of an interstitial fluid glucose detection device based on a porous microneedle array in an embodiment of the present application; Figure 3 1 is a partial view of a porous microneedle with a porosity gradient in an embodiment of the present application, wherein (a) is the needle tip; (b) is the middle of the needle body; and (c) is the part of the needle body close to the microneedle base; Figure 4 This is a graph showing the performance results of the simulated interstitial fluid in the colorimetric detection at 0-10 mM glucose in the embodiment of the present application; Figure 5 This is a graph showing the performance results of the simulated interstitial fluid in the electrochemical detection of 0-10 mM glucose in the examples of the present application.

[0029] Figure numerals: 1. microneedle module; 11. porous microneedle array; 12. porous microneedle; 2. colorimetric detection module; 21. liquid conducting layer; 22. colorimetric film; 3. electrochemical detection module; 31. lower substrate; 32. upper substrate; 33. nanosilver conductive circuit; 331. reference electrode; 332. working electrode; 333. counter electrode; 34. porous conductive carrier with immobilized enzyme; 35. hydrogel; 4. epidermis; 5. dermis. DETAILED DESCRIPTION

[0030] The English abbreviations in the text are as follows: PGA(Polyglycolide acid):polyglycolide; TMB (Tetramethylbenzidine): 3.3'5.5'-tetramethylbenzidine; PDMS (Polydimethylsiloxane): dimethylsiloxane; HFIP (Hexafluoroisopropanol): Hexafluoroisopropanol; PI (Polyimide): polyimide.

[0031] The following is combined with Figure 1-5 This application is described in further detail.

[0032] The present application embodiment discloses an interstitial fluid glucose detection device based on a porous microneedle array. Figure 1 The interstitial fluid glucose detection device based on the porous microneedle array includes a microneedle module 1, a colorimetric detection module 2, an electrochemical detection module 3 and a liquid conducting layer 21.

[0033] Reference Figure 1 and Figure 2 The microneedle module 1 includes a porous microneedle array 11 for piercing the human epidermis and drawing interstitial fluid. The porous microneedle array 11 includes a microneedle base and a plurality of porous microneedles 12 arrayed on the microneedle base. The porous microneedles 12 have a porosity gradient, and the porosity gradually increases from the needle tip to the microneedle base.

[0034] The method for preparing the porous microneedle array 11 with a porosity gradient comprises the following steps: Step 1, positive mold preparation: Prepare a positive mold of a microneedle array by 3D printing, the substrate size is 10 mm × 10 mm, 36 quadrangular pyramidal microneedles are evenly distributed 6 × 6 on it, the distance between adjacent microneedles is 1 mm, the length and width of a single microneedle base are 480 μm, the height is 900 μm, and the sharp angle is 30°; Step 2, negative mold preparation: Cover the negative mold material PDMS on the surface of the microneedle array positive mold, and obtain the microneedle array negative mold after demoulding; Step 3, solvent evaporation: inject a hexafluoroisopropanol solution of polyglycolide (polyglycolide concentration is 50 mg / mL) into the negative mold of the microneedle array, place the negative mold of the microneedle array upright (open end facing up, needle tip facing down), and evaporate the hexafluoroisopropanol in a directional manner, that is, the solvent in the needle body evaporates first, and the solvent in the needle tip evaporates later, and the obtained porous microneedle array 11 has a micron-scale spatial network structure and a porosity gradient. Figure 3 As shown, the porosity gradually increases from the needle tip to the microneedle base, and the porosity gradient ranges from 7% to 48%.

[0035] The needle tip with smaller porosity has greater strength and thus stronger puncture ability, which helps to reduce the pain of puncture; the needle body with larger porosity has good water absorption ability to achieve rapid absorption of interstitial fluid and provide sufficient target for colorimetric detection and electrochemical detection.

[0036] Reference Figure 1 and Figure 2 The liquid-conducting layer 21 is a polyglycolide porous membrane attached to the microneedle substrate, with an average thickness of 49 μm, pores with a distribution diameter of 1-5 μm, and a porosity of 42%. The liquid-conducting layer 21 is used to transfer the interstitial fluid drawn by the porous microneedle array 11 to the colorimetric detection module 2 and the electrochemical detection module 3 at the same time.

[0037] Reference Figure 1 and Figure 2 The colorimetric detection module 2 includes a colorimetric film 22 for reacting with glucose in the interstitial fluid to develop color. The colorimetric film 22 is a TMB functionalized porous film fixed with glucose oxidase and horseradish peroxidase. The colorimetric film 22 is attached to the liquid-conducting layer 21 .

[0038] The preparation method of the colorimetric film comprises the following steps: Step 1: Dissolve 10 mg of TMB in 2 mL of polyglycolide hexafluoroisopropanol (PGA-HFIP) solution, where the concentration of polyglycolide is 50 mg / mL, mix well and spread on the substrate to volatilize the hexafluoroisopropanol to obtain a TMB-functionalized porous film with a porosity of 43%; During the evaporation of the solvent, polyglycolide and TMB are precipitated simultaneously, so that TMB can be evenly distributed and fixed in the spatial network structure of polyglycolide, significantly reducing the "coffee ring effect", which is beneficial to improving the color uniformity and stability of the colorimetric film.

[0039] Step 2: Add 2 μL of glucose oxidase and horseradish peroxidase solution (the concentration of both enzymes is 100 U / mL) to the TMB-functionalized porous film, so that the glucose oxidase and horseradish peroxidase are adsorbed in the porous structure of the TMB-functionalized porous film to obtain a colorimetric film.

[0040] Reference Figure 1 and Figure 2 The electrochemical detection module 3 includes a flexible substrate and a three-electrode system disposed on the flexible substrate, wherein the three-electrode system includes a counter electrode 333, a reference electrode 331, and a working electrode 332. The three-electrode system is encapsulated by a hydrogel 35, and the hydrogel 35 is attached to the liquid-conducting layer 21.

[0041] Reference Figure 1 and Figure 2The flexible substrate includes a lower substrate 31 and an upper substrate 32. The lower substrate 31 is a polyimide (PI) film with a thickness of 50 μm and a size of 15 mm×5 mm, and the upper substrate 32 is a polydimethylsiloxane (PDMS) film with a thickness of 70 μm and a size of 15 mm×5 mm. The upper substrate 32 is subjected to oxygen plasma modification and then inkjet-printed with a nanosilver conductive line 33 with a line width of 100 μm. The flexible substrate printed with the nanosilver conductive line 33 is placed at 150°C for sintering and curing, and then the reference electrode 331, the counter electrode 333 and the working electrode 332 are prepared as follows: The reference electrode 331 and the counter electrode 333 are Ag / AgCl electrodes obtained by chlorination treatment of the nanosilver conductive circuit 33 .

[0042] Reference Figure 1 and Figure 2 The working electrode 332 includes a conductive circuit in a cross-comb structure, with a tooth spacing of 150 μm and an average resistivity of 2.7 Ω / mm. The conductive circuit in the cross-comb structure is covered with a porous conductive carrier 34 on which an enzyme is fixed. The porous conductive carrier is a porous particle of polyglycolide adsorbed with carbon nanotubes, on which glucose oxidase is loaded.

[0043] The preparation method of polyglycolide porous particles is as follows: slowly add an equal amount of water to a 50 mg / mL PGA-HFIP solution and slowly stir to produce polyglycolide floccules; then stir at high speed to break the polyglycolide floccules to obtain polyglycolide porous particles. By controlling the time of high-speed stirring, polyglycolide porous particles with different particle size ranges can be obtained. In this embodiment, the high-speed stirring time is 48 hours, and the particle size of the obtained polyglycolide porous particles is 10-20 μm.

[0044] After mixing carbon nanotubes with polyglycolide porous particles, glucose oxidase is added to obtain a porous conductive carrier 34 with enzyme fixed thereon, which is then coated on the conductive line of the cross-comb structure in the working electrode 332 region to complete the preparation of the working electrode 332. Finally, the three-electrode system is encapsulated using a hydrogel 35 to complete the preparation of the electrochemical detection module 3.

[0045] In the steps of preparing the porous microneedle array, preparing the colorimetric film, and preparing the polyglycolide porous particles, the preparation method of the polyglycolide hexafluoroisopropanol solution (PGA-HFIP solution) is as follows: The polyglycolide particles were wrapped in aluminum foil, and then placed on a hot press chassis preheated at 230°C, and heated for 100 seconds to completely melt the polyglycolide particles; then the temperature was maintained and the hot press was operated to apply pressure, and pressed at the set pressure for 100 seconds; after the hot pressing treatment, the aluminum foil wrapped with polyglycolide was taken out of the hot press, cooled at room temperature for 15 seconds, and peeled off from the aluminum foil to obtain a low-crystallinity polyglycolide film; the low-crystallinity polyglycolide film was dissolved in hexafluoroisopropanol to obtain a hexafluoroisopropanol solution of polyglycolide (PGA-HFIP solution).

[0046] By hot pressing, polyglycolide particles with a diameter of several millimeters are pressed into a film hundreds of microns thick, which greatly increases the heat exchange area and enables rapid cooling in room temperature air. At the same time, the high thermal conductivity of aluminum foil is used to quench the polyglycolide film in the air to block the recrystallization process of polyglycolide, thereby reducing the crystallinity of polyglycolide and making it easily soluble in organic solvents such as hexafluoroisopropanol.

[0047] After completing the preparation of the microneedle module 1, the colorimetric detection module 2 and the electrochemical detection module 3, the modules are assembled into an interstitial fluid glucose detection device and attached to human skin. The porous microneedles 12 pierce the epidermis 4 of the skin, and the interstitial fluid migrates to the microneedle base through the pore channels inside the porous microneedle array 11, and is quickly transferred to the two detection modules by the liquid conducting layer 21.

[0048] In the colorimetric detection module 2, the interstitial fluid diffuses in the colorimetric film 22, and the glucose oxidase oxidizes the glucose in the interstitial fluid to produce hydrogen peroxide, which further reacts with TMB under the action of horseradish peroxidase to produce a colored product. The higher the glucose concentration, the more colored products are produced and the darker the color; the glucose concentration can be detected according to the depth of the color.

[0049] In the electrochemical detection module 3, the glucose in the interstitial fluid reacts with the glucose oxidase in the working electrode to produce hydrogen peroxide. When a certain potential is applied externally, the hydrogen peroxide oxidizes and decomposes to produce electrons. The higher the glucose concentration, the more hydrogen peroxide is produced, that is, the more electrons, the greater the current generated. The glucose concentration in the interstitial fluid can be analyzed by detecting the magnitude of the current.

[0050] The detection results of the colorimetric detection module 2 on the simulated interstitial fluid containing 0-10mM glucose are as follows Figure 4 The test showed uniform color distribution, without large areas of obvious color difference, and the color gradients of different glucose concentrations were obvious. The gray value of the color was calibrated against the glucose concentration, showing good linearity, which can cover the linear detection range of normal fluctuations of human blood sugar. The sensitivity was 10.07 / mM, R 2 =0.977. The specific value of the detection accuracy is shown in Table 1, and the detection accuracy is 96.2%.

[0051] Table 1 Detection accuracy results of colorimetric detection module

[0052] The detection effect of the electrochemical detection module 3 on the simulated interstitial fluid containing 0-10 mM glucose is as follows Figure 5 ,With the increase of glucose concentration, the response current increases accordingly, and the response current at 10s shows an obvious ,distinction.,The specific values ​​of detection accuracy are shown in Table 2. The average detection accuracy of the ,electrochemical sensor module is 97.8%.

[0053] Table 2 Detection accuracy results of electrochemical detection module

[0054] This application can perform both rapid and accurate detection of interstitial fluid glucose concentration, and is suitable for different application scenarios, providing a convenient and accurate solution for assessing blood sugar levels for diabetic patients and people at risk.

[0055] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An interstitial fluid glucose detection device based on a porous microneedle array, characterized in that: include: A microneedle module, comprising a porous microneedle array for piercing the human epidermis and drawing interstitial fluid, wherein the porous microneedle array comprises a microneedle substrate and a plurality of porous microneedles arrayed on the microneedle substrate, wherein the porous microneedles have a porosity gradient, and the porosity gradually increases from the needle tip to the microneedle substrate; A colorimetric detection module, comprising a colorimetric film for reacting with glucose in the interstitial fluid to develop color, wherein the depth of the developed color is related to the glucose concentration; An electrochemical detection module, comprising a flexible substrate and a three-electrode system disposed on the flexible substrate, wherein the three-electrode system comprises a counter electrode, a reference electrode and a working electrode, and glucose in the interstitial fluid undergoes an oxidation-reduction reaction on the working electrode and generates a current signal related to the glucose concentration; The liquid conducting layer is attached to the microneedle substrate and is used to transfer the interstitial fluid drawn by the porous microneedle array to the colorimetric detection module and the electrochemical detection module at the same time.

2. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The porous microneedle is in a quadrangular pyramid shape.

3. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The porous microneedle has a micrometer-scale spatial network structure.

4. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The method for preparing the porous microneedle array having a porosity gradient comprises the following steps: Positive mold preparation: Prepare the positive mold of the microneedle array by 3D printing; Negative mold preparation: Cover the negative mold material on the surface of the microneedle array positive mold, and obtain the microneedle array negative mold after demoulding; Solvent evaporation: The hexafluoroisopropanol solution of polyglycolide is injected into the negative mold of the microneedle array, and the hexafluoroisopropanol is directionally evaporated to obtain a porous microneedle array with a porosity gradient.

5. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 4, characterized in that: In the solvent volatilization step, the solvent at the needle body evaporates first, and the solvent at the needle tip evaporates later.

6. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The colorimetric film is a TMB functionalized porous film on which glucose oxidase and horseradish peroxidase are fixed, and the colorimetric film is attached to the liquid-conducting layer.

7. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 6, characterized in that: The preparation method of the colorimetric film comprises the following steps: Dissolving TMB in a hexafluoroisopropanol solution of polyglycolide and spreading it on a substrate, allowing the hexafluoroisopropanol to evaporate, thereby obtaining a TMB-functionalized porous film; Glucose oxidase and horseradish peroxidase solutions were added dropwise to the TMB-functionalized porous film to obtain a colorimetric film.

8. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The three-electrode system is coated with a hydrogel layer, and the hydrogel layer is attached to the liquid-conducting layer.

9. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The working electrode comprises a conductive circuit in a cross-comb structure and a porous conductive carrier covering the conductive circuit, and the porous conductive carrier is loaded with glucose oxidase.

10. The interstitial fluid glucose detection device based on a porous microneedle array according to claim 1, characterized in that: The porous conductive carrier is polyglycolide porous particles adsorbed with carbon nanotubes.

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