Sweat in-situ detection sensor based on microneedle patch and preparation method thereof

Abstract

The invention discloses a sweat in-situ detection sensor based on a microneedle patch and a preparation method of the sweat in-situ detection sensor, and belongs to the technical field of sweat detection. The sweat in-situ detection sensor comprises a flexible substrate, and the flexible substrate comprises a hydrophobic layer used for being in contact with skin; the hydrophilic layer is arranged on the hydrophobic layer, and the sweat contact angle of the hydrophilic layer is smaller than that of the hydrophobic layer; the micro-channel layer comprises a micro-needle patch, and the micro-needle patch is arranged on the side, away from the hydrophobic layer, of the hydrophilic layer; the aggregation layer is arranged on the side, away from the hydrophilic layer, of the microneedle patch; the detection electrode is arranged between the aggregation layer and the microneedle patch; the volatilization layer is arranged on the side, away from the microneedle patch, of the aggregation layer, the problems that according to an existing wearable sweat detection sensor, the sweat utilization rate is not saturated, sweat is accumulated and flows back, a trace amount of sweat is difficult to fully utilize, and the detection precision of physiological signals is affected can be solved, and the application potential is huge.

Description

Technical Field

[0001] The present application belongs to the technical field of sweat detection, and specifically relates to a sweat in-situ detection sensor based on a microneedle patch and a preparation method thereof. Background Art

[0002] Human sweat is rich in biomarkers that can be used for physiological health testing and analysis. For example, a large number of clinical trials have shown that sweat glucose content can be used as a daily monitoring indicator for diabetic patients, and sweat uric acid index can reflect purine intake and be used for gout prevention. Compared with other body fluid tests (such as blood, saliva, etc.), sweat testing not only has the advantages of being non-invasive and non-invasive, but also has a richer variety of biomarkers that can be measured. In recent years, wearable sweat detection sensors based on flexible electronic technology can be conformally attached to the skin surface, solving the problems of poor real-time performance and cumbersome detection process in traditional sweat detection technology. Integrating sweat collection, transportation, detection and analysis into the skin surface is an important development direction in the future.

[0003] Although some existing sweat in situ detection sensors use the hydrophilic and hydrophobic differences of the Janus membrane to guide the directional transport of sweat, they ignore the balance between the sweat evaporation rate and the sweat transport rate; when the amount of sweat increases suddenly (in hot weather, strenuous exercise, etc.), the evaporation of sweat is less than the secretion amount, which will cause sweat accumulation and trigger sweat reflux.

[0004] Some other in situ sweat sensors have problems such as small amounts of sweat being difficult to fully utilize, affecting the detection accuracy of physiological signals, or the preparation process is very complicated (such as involving photolithography and laser processing). Summary of the invention

[0005] The purpose of the present application is to provide a sweat in situ detection sensor based on a microneedle patch and a preparation method thereof, which can solve at least one of the problems existing in the prior art, so as to realize unidirectional transport of sweat, prevent sweat reflux and improve sweat utilization.

[0006] In order to solve the above technical problems, this application is implemented as follows: In a first aspect, the present application provides a sweat in-situ detection sensor based on a microneedle patch, comprising: Flexible substrate, the flexible substrate includes: A hydrophobic layer for contact with the skin; A hydrophilic layer, the hydrophilic layer is disposed on the hydrophobic layer, and the sweat contact angle of the hydrophilic layer is smaller than the sweat contact angle of the hydrophobic layer; Microchannel layer, the microchannel layer includes: A microneedle patch, wherein the microneedle patch is arranged on the side of the hydrophilic layer away from the hydrophobic layer; An aggregation layer, which is disposed on a side of the microneedle patch away from the hydrophilic layer; Detection electrode, which is arranged between the aggregation layer and the microneedle patch; Volatile layer, which is arranged on the side of the aggregation layer away from the microneedle patch.

[0007] Furthermore, the microneedle patch includes: Patch body; Multiple openings, which are formed through the patch body; Multiple conical structures, which are respectively located in each opening. There is a short channel between the conical structure and the inner wall of the opening. The conical structure protrudes towards the hydrophilic layer and contacts the hydrophilic layer; Connecting structure, which is located in the opening and is respectively connected to the conical structure and the patch body.

[0008] Furthermore, the conical structure includes any axial longitudinal section containing or parallel to the central axis. The outer contour line of the axial longitudinal section forms a continuous curvature gradient from the top to the bottom, and the curvature of any point on the outer contour line gradually decreases from the top to the bottom; The conical structure includes any radial cross-section perpendicular to the central axis. The outer contour line of the radial cross-section is an elliptical curve with a major axis and a minor axis, and a continuous curvature gradient is formed in the direction from the end point of the major axis to the end point of the minor axis. The curvature of any point on the outer contour of the radial cross-section gradually decreases from the end point of the major axis to the end point of the minor axis.

[0009] Furthermore, the opening is in the shape of a frustum of a cone, and the diameter of the circular cross-section on the side of the opening close to the hydrophilic layer is larger than the diameter of the circular cross-section on the side close to the aggregation layer; The corresponding apex angle of the conical structure at the end point of the minor axis of the radial cross-section is 3° - 15°; The ratio of the major axis to the minor axis of the radial cross-section is 1.5 - 2.5:1.

[0010] Furthermore, there are two connecting structures, which are oppositely arranged in the area between the inner walls of the openings corresponding to the end points of the major axis of the radial cross-section.

[0011] Furthermore, the aggregation layer includes: Concave conical pipe, which is arranged on the side of the aggregation layer close to the microneedle patch and is aligned with the conical structure array; Receiving groove, which is on the same side of the aggregation layer as the concave conical pipe and is used to receive the detection electrode.

[0012] Furthermore, from the end of the concave conical pipe far away from the receiving groove to the end close to the receiving groove, the radius of the semi-circular cross-section of the concave conical pipe gradually decreases.

[0013] Furthermore, the detection electrode includes an electrode deposition layer, a signal transmission wire, and a sensing electrode; the signal transmission wire and the sensing electrode are arranged on the surface of the electrode deposition layer.

[0014] Second aspect, the present application discloses a preparation method of a sweat in-situ detection sensor, including the following steps: The preparation steps of the flexible substrate include: Deposit a uniform nanofiber membrane on the silicon wafer to obtain a hydrophobic layer; Deposit a uniform nanofiber membrane on the hydrophobic layer, and coat a hydrophilic polymer on the surface of the nanofiber membrane to obtain a hydrophilic layer; The preparation steps of the microchannel layer include: Design a microneedle patch model, prepare a microneedle patch mold according to the microneedle patch model, and pour the matrix material into the microneedle patch mold to obtain a microneedle patch; Design an aggregation layer model, prepare an aggregation layer mold according to the aggregation layer model, and pour the matrix material into the aggregation layer mold to obtain an aggregation layer; The preparation steps of the detection electrode include: Deposit a uniform nanofiber membrane on the silicon wafer to obtain an electrode deposition layer; Prepare a signal transmission wire sensing electrode on the electrode deposition layer; The preparation steps of the volatilization layer include: Deposit a nanofiber membrane on the aggregation layer, and coat a hydrophilic polymer on the side of the nanofiber membrane away from the aggregation layer to obtain a volatilization layer; Combine the flexible substrate, the microchannel layer, the detection electrode, and the volatilization layer to prepare a sweat in-situ detection sensor.

[0015] Furthermore, the preparation method specifically includes: Prepare a uniform TPU nanofiber membrane on the silicon wafer through an electrospinning process to obtain a hydrophobic layer; Prepare a uniform PAN nanofiber membrane on the hydrophobic layer through an electrospinning process, and coat a hydrophilic polymer PVP on the surface of the PAN nanofiber membrane to obtain a hydrophilic layer; Design a microneedle patch model, prepare a microneedle patch mold according to the microneedle patch model, and then pour the pre-prepared polydimethylsiloxane into the microneedle patch mold, and demold after curing to obtain a microneedle patch; Design an aggregation layer model, prepare an aggregation layer mold according to the aggregation layer model, and then pour the pre-prepared polydimethylsiloxane into the aggregation layer mold, and demold after curing to obtain an aggregation layer; Prepare a thermoplastic graphene oxide / TPU composite nanofiber membrane on the silicon wafer through an electrohydrodynamic direct writing process to obtain an electrode deposition layer; Form patterned liquid metal on the electrode deposition layer through a transfer process to obtain a signal transmission wire; Prepare a sensing electrode on the electrode deposition layer through a screen printing process, and the sensing electrode includes a working electrode, a counter electrode, and a reference electrode; A uniform PAN nanofiber membrane is prepared on the upper surface of the aggregation layer through an electrospinning process, and a volatilization layer is obtained by coating a hydrophilic polymer on the side of the PAN nanofiber membrane away from the aggregation layer. Among them, the fiber diameter and porosity of the TPU nanofiber membrane, PAN nanofiber membrane, and thermoplastic graphene oxide / TPU composite nanofiber membrane can all be regulated by adjusting parameters such as the electrospinning electric field strength, nozzle distance, solution supply flow rate, and fiber packing density.

[0016] This application has at least the following beneficial effects: (1) This application ingeniously designs a two-dimensional gradient conical structure, enabling sweat to spontaneously move upward and avoid the obstruction of the channel connection structure, improving the utilization rate of sweat while achieving directional transport and ensuring the accuracy of physiological signal detection.

[0017] (2) The concave conical pipeline of the aggregation layer designed in this application can drive sweat to spontaneously converge towards the detection electrode arranged in the accommodation groove of the aggregation layer.

[0018] (3) This application uses a multi-scale structure nanofiber membrane as the volatilization layer to timely discharge the measured sweat, maintain the balance between sweating and transpiration, and improve the accuracy of sweat detection.

[0019] (4) It is simple to prepare and does not involve expensive and time-consuming process steps such as photolithography and sputtering. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of a sweat in-situ detection sensor based on a microneedle patch provided by an embodiment of this application.

[0021] Figure 2 It is a schematic axial longitudinal sectional view of the conical structure provided by an embodiment of this application.

[0022] Figure 3 It is a schematic radial cross-sectional view of the conical structure provided by an embodiment of this application.

[0023] Figure 4 It is a partial structural diagram of the microneedle patch provided by an embodiment of this application.

[0024] Figure 5 It is a partial structural diagram of the aggregation layer provided by an embodiment of this application.

[0025] Figure 6 It is a diagram of a single pipeline in the aggregation layer provided by an embodiment of this application.

[0026] Figure 7 It is a flow block diagram of a method for preparing a sweat in-situ detection sensor based on a microneedle patch provided by an embodiment of this application.

[0027] Figure 8Schematic diagram of the sweat transport path provided by the embodiments of the present application.

[0028] Figure 9 Simulation result diagrams of different apex angles of a single microneedle unit of the microneedle patch provided by Embodiment 1 of the present application.

[0029] Figure 10 Simulation result diagrams of different length-to-diameter ratios of a single microneedle unit of the microneedle patch provided by Embodiment 1 of the present application.

[0030] Figure 11 Experimental diagram of the directional transport of the test liquid in the aggregation layer provided by Embodiment 1 of the present application.

[0031] Figure 12 Linear fitting curve diagram of the measured peak current and glucose concentration provided by Embodiment 1 of the present application.

[0032] Reference numerals: 100, flexible substrate; 110, hydrophobic layer; 120, hydrophilic layer; 200, microchannel layer; 210, microneedle patch; 211, patch body; 212, opening; 213, conical structure; 214, connection structure; 220, aggregation layer; 221, concave conical pipe; 222, accommodation groove; 300, detection electrode; 310, electrode deposition layer; 320, signal transmission wire; 330, sensing electrode; 400, volatilization layer. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0034] The present application provides a sweat in-situ detection sensor based on a microneedle patch, as Figure 1 shown, the detection sensor includes: A flexible substrate 100, and the flexible substrate 100 includes: A hydrophobic layer 110 for contacting the skin; A hydrophilic layer 120, the hydrophilic layer 120 is disposed on the hydrophobic layer 110, and the sweat contact angle of the hydrophilic layer 120 is smaller than the sweat contact angle of the hydrophobic layer 110.

[0035] It should be noted that the flexible substrate 100 is prepared by layer-by-layer depositing nanofiber membranes through an electrospinning process, and has high flexibility - it can conformally adhere to the skin. Its porous structure has good permeability - facilitating the passage of fluids. The hydrophobic layer 110 is hydrophobic to sweat. Directly adhering to the skin can ensure the dryness of the covered area and improve the wearing comfort. The sweat contact angle of the hydrophilic layer 120 is smaller than that of the hydrophobic layer 110, and it can guide the sweat on the hydrophobic layer 110 to climb upward along the fibers of the nanofiber membrane and be transported to the hydrophilic layer 120.

[0036] The microchannel layer 200, and the microchannel layer 200 includes: The microneedle patch 210, and the microneedle patch 210 is disposed on the side of the hydrophilic layer 120 away from the hydrophobic layer 110; The aggregation layer 220, and the aggregation layer 220 is disposed on the side of the microneedle patch 210 away from the hydrophilic layer 120; In this embodiment, the microneedle patch 210 is located between the hydrophilic layer 120 and the aggregation layer 220, and can further transport the sweat of the hydrophilic layer 120 to the aggregation layer 220, realizing the directional transportation of sweat without backflow.

[0037] In some embodiments of the present application, the microneedle patch 210 includes: The patch body 211; A plurality of openings 212, which are penetrated through the patch body 211; A plurality of conical structures 213, which are respectively located in each opening 212. There is a channel between the conical structure 213 and the inner wall of the opening 212. The conical structure 213 protrudes toward the hydrophilic layer 120 and contacts the hydrophilic layer 120; The connection structure 214, which is located in the opening 212 and is respectively connected to the conical structure 213 and the patch body 211.

[0038] Furthermore, as Figure 2 shown, the conical structure 213 includes any axial longitudinal section containing or parallel to the central axis. The outer contour line of any axial longitudinal section forms a continuous curvature gradient from the top to the bottom, and the curvature of any point on the outer contour line gradually decreases from the top to the bottom; As Figure 3 shown, the conical structure 213 includes any radial cross-section perpendicular to the central axis. The outer contour line of any radial cross-section is an elliptical curve with a major axis and a minor axis, and forms a continuous curvature gradient in the direction from the major axis endpoint to the minor axis endpoint. The curvature of any point on the outer contour of the radial cross-section gradually decreases from the major axis endpoint to the minor axis endpoint.

[0039] It should be noted that the top is the area where the radius of curvature R of the conical structure 213 in the axial direction is smaller, and the bottom is the area where the radius of curvature R of the conical structure 213 in the axial direction is larger. Figure 2 In [reference] B_B refers toFigure 3 where the intercepted radial cross-section is located Figure 2 in the position within.

[0040] The major axis endpoints and minor axis endpoints, i.e., the major axis and minor axis of the outer contour line of any radial cross-section, and the intersection points of the ellipse circumference (outer contour line).

[0041] The two-dimensional (i.e., axial and radial) curvature gradient characteristic of the conical structure can enable the conical structure 213 to transport sweat directionally, and the two working together can achieve the automatic avoidance of sweat from the connection structure, thereby improving the utilization rate of sweat and ensuring no backflow.

[0042] The specific analysis process of how the two-dimensional curvature gradient characteristic can transport sweat directionally through Laplace pressure is as follows: Axially, due to the convex conical surface of the conical structure, the curvature on both sides of the sweat is different, and the resulting Laplace pressure difference drives the sweat to move from the large curvature (top) to the small curvature (bottom). The specific analysis process is as follows: The Laplace pressure exerted on the sweat in any axial longitudinal section is: P = (1 - 1) where R is the radius of curvature of any axial longitudinal section, γ is the surface tension of the sweat, and r is the radius of the sweat. The Laplace pressure is differentiated with respect to x in its axial direction, and the Laplace pressure exerted on each component of the sweat is obtained as: + ) (1 - 2) Assume that the radius r of the sweat (spherical surface) does not change with x, i.e., = 0, then there is: (1 - 3) In the xy coordinate system, R = tanα * x (x is the axial variable, α is the conical apex angle), i.e., α (1 - 4) Substitute formula (4) into formula (3) to get: α (1 - 5) The above formula is rewritten as: αdx (1 - 6) Therefore, the Laplace pressure difference generated by the sweat on both sides of the conical structure is shown in the following formula: ΔP = (1 - 7) So, the Laplace pressure difference depends on the apex angle α corresponding to the minor axis endpoint of the outer contour line of any radial cross-section (verified by simulation in Example 1).

[0043] Since the Laplace pressure on the sweat in the top region is greater than that in the bottom region, the pressure difference inside the sweat drives the sweat to move from the top to the bottom.

[0044] The radially elliptical cross-section also uses the Laplace pressure difference to drive the sweat to gather at the location of the smaller curvature. The specific analysis process is as follows: The major axis of the ellipse is a, and the minor axis is b; for simplicity in calculation, a and b are scaled proportionally. Let b = 1 and a = kb = k.

[0045] According to the Laplace pressure formula: ΔP = γ( (1 - 8) where K is the radius of curvature of the micro-element unit. In this model, , , then we have: ΔP = (1 - 9) Taking the derivative of the Laplace pressure in the x direction, the Laplace pressure on each component of the sweat is obtained as: + )(1 - 10) Assuming that the radius r (cross-sectional circle) of the sweat does not change with x, that is, = 0, then we have: (1 - 11) According to the formula for the radius at any point on the ellipse: R = (1 - 12) Substituting formula (12) into formula (11) gives: = * * *( )(1 - 13) Taking the first derivative of the ellipse equation with respect to x gives: = (1 - 14) Substituting formula (14) into formula (13) gives: = * * *( )(1 - 15) Therefore, the Laplace pressure difference generated by the sweat in the radially elliptical cross-section is shown in the following formula: ΔP = * *( )dx(1-16) Wherein y is a function of x, the Laplace pressure difference depends on the ratio k of a to b (confirmed by simulation in Example 1), the outer contour line of any radial cross section is an elliptical curve with a major diameter and a minor diameter, and a continuous curvature gradient is formed in the direction from the end point of the major diameter to the end point of the minor diameter. The curvature of any point on the outer contour of the radial cross section gradually decreases. It can be seen that the Laplace pressure on the sweat at the curvature radius R at the end point of the major diameter is greater than the curvature radius R at the end point of the minor diameter, and the pressure difference inside the sweat drives the sweat to move toward the mother line at the small curvature.

[0046] Furthermore, the opening 212 is in a truncated cone structure, and the diameter of the circular cross section of the opening 212 close to the hydrophilic layer 120 is larger than the diameter of the circular cross section of the opening 212 close to the aggregation layer 220; The corresponding vertex angle of the conical structure 213 at the end point of the short diameter of the radial cross section is 3° to 15°; The aspect ratio of the radial cross section is 1.5~2.5:1.

[0047] like Figure 4 As shown, in some embodiments, through simulation experiments, it is found that the transport efficiency is highest when the corresponding vertex angle at the end point of the short diameter of the radial cross-section is 8°, and when the aspect ratio of the radial cross-section is 1.8:1, the amount of sweat film formation is the least and the transport effect is the best.

[0048] It is worth noting that the opening 212 is a truncated cone structure, and the diameter of the circular cross-section of the opening 212 close to the hydrophilic layer 120 is larger than the diameter of the circular cross-section of the side close to the gathering layer 220, so that the channel between the conical structure 213 and the inner wall of the opening 212 can provide an escape space for the directional transport of sweat, and its inner surface also has a curvature gradient change, which can provide driving force at the same time as the outer surface of the conical structure, further promoting the directional movement of sweat to the gathering layer. Furthermore, there are two connection structures 214 , which are disposed opposite to each other in the region between the inner walls of the opening 212 corresponding to the end points of the major diameter of the radial cross section.

[0049] like Figure 5 As shown, the aggregation layer 220 includes: A concave conical channel 221, which is disposed on one side of the aggregation layer 220 close to the microneedle patch 210 and is aligned with the array of conical structures 213; The receiving groove 222 and the concave tapered pipe 221 are located on the same side of the gathering layer 220 and are used to receive the detection electrode 300 .

[0050] Furthermore, if Figure 6As shown, the concave conical pipe 221 has a gradually decreasing semi-circular cross-sectional radius from one end far from the central region of the aggregation layer to one end close to the central region of the aggregation layer.

[0051] It should be noted that the concave conical pipe 221 is aligned with the array of conical structures 213 on the microneedle patch. Under the combined action of the pipe structure and the microneedle patch, sweat converges towards the central region where the detection electrode is located, completing the process of sweat collection.

[0052] Furthermore, the detection electrode 300 is disposed between the aggregation layer 220 and the microneedle patch 210.

[0053] In this embodiment, the detection electrode 300 includes an electrode deposition layer 310, a signal transmission wire 320, and a sensing electrode 330; the signal transmission wire 320 and the sensing electrode 330 are disposed on the surface of the electrode deposition layer 310.

[0054] In some embodiments of the present application, the signal transmission wire is prepared by liquid metal transfer printing, and the sensing electrode can be a three-electrode system for glucose detection, where the reference electrode is Ag / AgCl ink, the counter electrode is conductive carbon paste, and the working electrode is conductive carbon paste (attached with glucose oxidase).

[0055] Furthermore, the volatilization layer 400 is disposed on the side of the aggregation layer 220 facing away from the microneedle patch 210, and is prepared by layer-by-layer deposition of nanofiber membranes through electrospinning. Utilizing the porous structure and longitudinal wetting gradient characteristics, the measured sweat can be discharged in a timely manner, and adjusting the fiber structure can also optimize sweat volatilization, thereby ensuring more sufficient detection and improving detection sensitivity.

[0056] The present application discloses a preparation method for a sweat in-situ detection sensor, as Figure 7 including the following steps: Preparation step of the flexible substrate 100: Prepare a uniform TPU nanofiber membrane on a silicon wafer through electrospinning to obtain the hydrophobic layer 110; Prepare a uniform PAN nanofiber membrane on the hydrophobic layer 110 through electrospinning, and coat the hydrophilic polymer PVP on the surface of the PAN nanofiber membrane to obtain the hydrophilic layer 120; Preparation step of the microchannel layer 200: Design a microneedle patch model, prepare a microneedle patch mold according to the microneedle patch model, and then pour the pre-prepared polydimethylsiloxane (PDMS) into the microneedle patch mold, and demold after curing to obtain the microneedle patch 210; Design an aggregation layer model, prepare an aggregation layer mold according to the aggregation layer model, and then pour the pre-prepared polydimethylsiloxane (PDMS) into the aggregation layer mold, and demold after curing to obtain the aggregation layer 220; Preparation steps of the detection electrode 300: Prepare a thermoplastic graphene oxide / TPU composite nanofiber membrane on a silicon wafer through an electrostatic direct writing process to obtain an electrode deposition layer 310; Form a patterned liquid metal on the electrode deposition layer 310 through a transfer process to obtain a signal transmission wire 320; Prepare a sensing electrode 330 on the electrode deposition layer 310 through a screen printing process. The sensing electrode 330 includes a working electrode, a counter electrode, and a reference electrode; Preparation steps of the volatilization layer 400: Prepare a uniform PAN nanofiber membrane on the upper surface of the aggregation layer 220 through an electrospinning process, and coat a hydrophilic polymer on the side of the PAN nanofiber membrane away from the aggregation layer 220 to obtain the volatilization layer 400; Among them, the TPU nanofiber membrane, the PAN nanofiber membrane, and the thermoplastic graphene oxide / TPU composite nanofiber membrane can all regulate the fiber diameter and pores by adjusting parameters such as the electrostatic spinning electric field strength, the nozzle distance, the solution supply flow rate, and the fiber packing density.

[0057] Combine the flexible substrate 110, the microchannel layer 200, the detection electrode 300, and the volatilization layer 400 to prepare a sweat in-situ detection sensor.

[0058] As Figure 8 shown, in this application, a microneedle patch and nanofibers are combined to construct a sweat in-situ detection sensor. Sweat directly contacts the hydrophobic layer 110 under the action of the sweat gland secretion pressure. Due to the wetting gradient and capillary force between the hydrophobic layer 110 and the upper hydrophilic layer 120, sweat self-permeates upward to the hydrophilic layer 120, ensuring no residual epidermal sweat. The microneedle patch 210 on the upper layer of the hydrophilic layer 120 has a double-dimensional gradient conical structure 230. There are Laplace pressure differences in the radial and axial directions of the conical structure for sweat, which spontaneously moves upward and can avoid obstacles at the short-channel connection, improving the sweat utilization rate while achieving directional transport and ensuring the accuracy of physiological signal detection. The concave conical pipe 221 of the aggregation layer can drive sweat to spontaneously converge to the detection electrode 300 arranged in the accommodation groove of the aggregation layer. The volatilization layer 400 has a longitudinal wetting gradient, which can timely discharge the measured sweat, improving the accuracy of sweat detection. In addition, the signal transmission wire uses liquid metal, which can still ensure signal transmission stability under deformation interference. Moreover, the sweat in-situ detection sensor prepared in this application is simple to prepare as a whole and does not involve expensive and time-consuming process steps such as lithography and sputtering.

[0059] The following uses specific embodiments to further elaborate on the present invention in detail, but this application is not limited to the following specific embodiments.

[0060] Embodiment 1 1. This embodiment provides a sweat in-situ detection sensor based on a microneedle patch. The detection sensor includes: A flexible substrate 100, and the flexible substrate 100 includes: A hydrophobic layer 110, which is prepared from a thermoplastic TPU composite nanofiber membrane, is mutually exclusive with sweat and does not undergo a wetting behavior. The contact angle of sweat is 148°.

[0061] A hydrophilic layer 120, which is prepared by coating polyvinylpyrrolidone (PVP) on the surface of a PAN nanofiber membrane. The wettability of this nanofiber membrane to sweat is better than that of the 11-hydrophobic layer, and the contact angle of sweat is 14°.

[0062] A microchannel layer 200, and the microchannel layer 200 includes: A microneedle patch 210, which is prepared by replicating a PDMS precursor. The required mold is obtained through micro-nano 3D printing technology. The apex angle of the microneedle is 8°, and the aspect ratio of the major axis to the minor axis of the cross-section ellipse is 1.8:1.

[0063] An aggregation layer 220, which is prepared by replicating a PDMS precursor. The required mold is obtained through micro-nano 3D printing technology. The structure has the characteristic of curvature gradient change, as shown.

[0064] A detection electrode 300, and the detection electrode 300 includes: An electrode deposition layer 310, which is prepared from a thermoplastic graphene oxide / TPU composite nanofiber membrane with a personalized pattern structure. This TPU composite nanofiber membrane has a wetting behavior towards liquid metal, and the contact angle is 26°.

[0065] A signal transmission wire 320, which is prepared by transferring a patterned liquid metal. The liquid metal components are gallium: indium: tin, and the mass ratio is 0.68:0.215:0.1, and the melting point is 11°C.

[0066] A sensing electrode 330. In this embodiment, it is a three-electrode system for glucose detection, including a working electrode, a counter electrode, and a reference electrode. The whole is prepared by a screen printing process. The reference electrode is Ag / AgCl ink, the counter electrode is conductive carbon paste, and the working electrode is conductive carbon paste (attached with glucose oxidase).

[0067] A volatile layer 440, which is composed of a PAN composite nanofiber membrane and has good wettability to sweat. The contact angle of sweat is 14°.

[0068] 2. The preparation method of the sweat in-situ detection sensor of this application includes the following steps: S1. Prepare the flexible substrate 100 The steps for preparing the hydrophobic layer 110 specifically include: Using ultrasonic-assisted technology, 10 g of TPU particles were uniformly dispersed in 85 g of DMF solvent, and then 5 g of inorganic filler was added. , and stirred evenly to obtain a TPU precursor solution. The obtained solution was uniformly deposited on a silicon wafer through an electrospinning process to prepare a PAN nanofiber membrane, obtaining a hydrophobic layer 110. Among them, the electrospinning voltage was 20 kV, the liquid supply rate was 300 μL / h, and the spinning distance was 15 cm.

[0069] The steps for preparing the hydrophilic layer 120 specifically include: Dissolve PAN particles in DMF solvent. Dissolve 10 g of PAN particles in 90 g of DMF solvent, and magnetically stir for 2 h to obtain a PAN precursor solution. The obtained solution was uniformly deposited on the hydrophobic layer through an electrospinning process to prepare a PAN nanofiber membrane, and 40 wt% of PVP was coated on the surface of the fiber membrane to prepare the hydrophilic layer 120. Among them, the electrospinning voltage was 20 kV, the liquid supply rate was 300 μL / h, and the spinning distance was 15 cm.

[0070] Peel the double-layer composite fiber membrane from the silicon wafer to obtain a flexible substrate 100.

[0071] S2. Prepare the microchannel layer 200 Design and optimize the mold of the microchannel layer through software such as SolidWorks and Fluent to obtain a micro-needle patch model and an aggregation layer model. Import the model into a 3D printing platform to make a physical mold to obtain a micro-needle patch mold and an aggregation layer mold; mix the PDMS solution and the curing agent according to a mass ratio of 10:1, and magnetically stir for 20 min to obtain a PDMS precursor solution with a total mass of 11 g. Take a part of the PDMS precursor solution and mix it evenly with ferromagnetic particles to obtain a PDMS / ferromagnetic particle mixture.

[0072] The steps for preparing the micro-needle patch 210 specifically include: Spray a release agent on the surface of the micro-needle patch mold, let it stand for 5 min, drop the PDMS / ferromagnetic particle mixture onto the 2 micro-needle patch mold, place a neodymium iron boron under the mold. After the mixture fills the fine structure of the mold under the action of magnetic force, crosslink at 150 °C for 2 h, cool and demold to obtain the micro-needle patch 210.

[0073] The steps for preparing the aggregation layer 220 specifically include: Spray a release agent on the surface of the aggregation layer mold, let it stand for 5 min, drop the PDMS precursor onto the aggregation layer mold, place it for 10 min and wait for the bubbles to disappear, then put it into a drying oven and bake at 90 °C for 2 h to cure, and demold to obtain the aggregation layer 220.

[0074] S3. Prepare the detection electrode 300 The steps for obtaining the electrode deposition layer 310 specifically include: Using ultrasonic-assisted technology, 0.01 g of GO powder was uniformly dissolved in 2 g of dimethylacetamide solvent. Subsequently, 0.9 g of TPU particles were added and magnetically stirred for 3 h to obtain a GO / TPU composite precursor solution. The obtained solution was used to prepare a nanofiber membrane with a personalized pattern on a silicon wafer through electrohydrodynamic direct writing technology; the electrohydrodynamic direct writing parameters were set as follows: direct writing voltage 2 kV, liquid supply rate 150 μL / h, and direct writing distance 1.5 cm.

[0075] The steps for preparing the signal transmission wire 320 specifically include: Select a copper cardboard as the transfer substrate and coat liquid metal on its surface; the coated substrate was dried. Through mechanical pressure, the liquid metal was transferred from the substrate to the surface of the electrode deposition layer 310 to form a patterned liquid metal. When the liquid metal penetrated into the electrode deposition layer 310, the signal transmission wire 320 was prepared; It should be noted that due to the wetting property of the electrode deposition layer 310 for liquid metal, the liquid metal will penetrate into the pores of the electrode deposition layer. The sensing electrode 330 does not have the wetting property for liquid metal, so the liquid metal only exists in the pores of the electrode deposition layer 310 and does not affect the sensing electrode 330 located on the surface of the electrode deposition layer 310.

[0076] The steps for preparing the sensing electrode 330 on the electrode deposition layer 310 specifically include: First, 60 mg of GO powder and 30 mg of glucose oxidase were fully dissolved in 36 mL of PBS buffer solution (0.1 mol / mL) to prepare a modified solution (33% enzyme content); on the electrode deposition layer 330, a reference electrode was prepared by screen printing Ag / AgCl ink in combination with a mask template, and a counter electrode and a working electrode were respectively prepared by screen printing conductive carbon paste. Immediately afterwards, a pipette was used to drop the enzyme-containing modified solution on the surface of the working electrode, dried at room temperature and repeated dropping 5 times to obtain the sensing electrode 330.

[0077] S4. The steps for preparing the evaporation layer 400 specifically include: 10 g of PAN particles were dissolved in 85 g of DMF solvent, and then 5 g of inorganic filler particles were added, and magnetically stirred for 2 h to obtain a PAN precursor. At room temperature, the PAN precursor was used for planar electrospinning on the aggregation layer 220. The electrospinning voltage was 20 kV, the liquid supply rate was 300 μL / h, and the spinning distance was 15 cm. Then, every 15 min, the voltage was reduced by 3 kV. In this way, a multi-scale fiber membrane with a gradually increasing fiber diameter from bottom to top could be obtained. 40 wt% of PVP was coated on the surface of the fiber membrane to obtain a PAN / PVP nanofiber membrane, that is, the evaporation layer 400 was prepared.

[0078] Assembly of the flexible substrate 100, microchannel layer 200, detection electrode 300, and evaporation layer 400 According to Figure 1 the vertical distribution shown, combine them, and evenly apply the PDMS precursor solution obtained in step S2 as an adhesive to the connection surfaces of each component. Then put it in a drying oven and bake at 90 °C for 2 h until completely cured to obtain the in-situ sweat detection sensor.

[0079] 3. Performance experiments: (1) Simulation test of the conical structure Perform a simulation test on the microneedle patch 210 prepared in step S2 above to detect the performance of the two-dimensional gradient conical structure of the microneedle patch 210. Among them, the apex angles of the conical structure are taken as 4°, 8°, and 14° respectively as three control groups; The aspect ratios of the major and minor axes of the radial cross-section are taken as 1.5:1, 1.8:1, and 2:1 respectively as three control groups.

[0080] (2) Aggregation effect test of the aggregation layer Drop the black liquid at the end of the pipeline, observe it statically and record the self-transport state of the liquid droplet at different times in a timely manner.

[0081] (3) Cyclic voltammetry test of the sensor Use the prepared in-situ sweat sensor to perform cyclic voltammetry tests on solutions with different glucose concentrations, and fit the peak currents obtained.

[0082] 4. Result analysis: As Figure 9 shown, by analyzing the simulation results, it can be seen that when the apex angle is 8°, the sweat transport rate is the highest.

[0083] As Figure 10 shown, it can be seen that when the aspect ratio of the major and minor axes of the radial cross-section is 1.8:1, the sweat film formation amount is small and the concentration effect is the best, which is more conducive to sweat transport and obstacle avoidance (the radial direction is mainly responsible for concentrating sweat and avoiding the connection structure), and thus more conducive to the transport of sweat.

[0084] As Figure 11 shown, it can be seen that the black liquid droplet spontaneously moves towards the central region, and the concave conical pipeline design of the aggregation layer has a good aggregation effect.

[0085] As Figure 12 shown, by analyzing the fitting curve, it can be seen that as the glucose concentration increases, the number of glucose molecules participating in the oxidation reaction increases, resulting in more electron transfers. These electron transfers form a current. Therefore, the glucose concentration is proportional to the peak current, and the peak current of the sensor can better reflect the glucose concentration.

[0086] Example 2 1. Another sweat in-situ detection sensor combining a microneedle patch and nanofibers provided by this embodiment and its preparation method. The sweat in-situ detection sensor includes: A flexible substrate 100, and the flexible substrate 100 includes: A hydrophobic layer 110, which is prepared from a thermoplastic TPU composite nanofiber membrane, is mutually exclusive with sweat and does not exhibit a wetting behavior. The contact angle of sweat is 148°.

[0087] A hydrophilic layer 120, which is prepared by ultraviolet light modification of a thermoplastic TPU nanofiber membrane. The wettability of this nanofiber membrane to sweat is better than that of the hydrophobic layer 110, and the contact angle of sweat is 70°.

[0088] A microchannel layer 200, and the microchannel layer 200 includes: A microneedle patch 210, which is prepared by replicating a PDMS precursor. The required mold is obtained through micro-nano 3D printing technology. The apex angle of the microneedle is 8°, and the aspect ratio of the major axis to the minor axis of the cross-sectional ellipse is 1.8.

[0089] An aggregation layer 220, which is prepared by replicating a PDMS precursor. The required mold is obtained through micro-nano 3D printing technology, and its structure has the characteristic of curvature gradient change.

[0090] A detection electrode 300, and the detection electrode 300 includes: An electrode deposition layer 310, which is prepared from a thermoplastic graphene oxide / TPU composite nanofiber membrane with a personalized pattern structure. This TPU composite nanofiber membrane exhibits a wetting behavior towards liquid metal, and the contact angle is 26°.

[0091] A signal transmission wire 320, which is prepared by transferring a patterned liquid metal. The liquid metal components are gallium: indium: tin, and the mass ratio is 0.68:0.215:0.1, and the melting point is 11 °C.

[0092] A sensing electrode 330. In this embodiment, it is a three-electrode system for uric acid detection, including a working electrode, a counter electrode, and a reference electrode. The whole is prepared by screen printing technology. The reference electrode is Ag / AgCl ink, the counter electrode is conductive carbon paste, and the working electrode is conductive carbon paste (attached with PEDOT modification material).

[0093] A volatile layer 400, which is composed of a PAN composite nanofiber membrane, has good wettability to sweat, and the contact angle of sweat is 14°.

[0094] 2. The preparation method of the sweat in-situ detection sensor includes the following steps: S1. Prepare the flexible substrate 100 The steps for preparing the hydrophobic layer 110 specifically include: Using ultrasonic-assisted technology, 10 g of TPU particles were uniformly dispersed in 85 g of DMF solvent, and then 5 g of inorganic filler was added. , and stirred evenly to obtain a TPU precursor solution. At room temperature, the obtained solution was used to prepare a hydrophobic layer 110 through an electrospinning process, where the electrospinning voltage was 20 kV, the liquid supply rate was 300 μL / h, and the spinning distance was 15 cm.

[0095] The steps for preparing the hydrophilic layer 120 specifically include: Using ultrasonic-assisted technology, 10 g of TPU particles were uniformly dispersed in 85 g of DMF solvent, and then 5 g of inorganic filler was added. After stirring evenly to obtain a TPU precursor solution, at room temperature, electrospinning was carried out on the hydrophobic layer 110 with the obtained solution (electrospinning voltage 20 kV, liquid supply rate 300 μL / h, spinning distance 15 cm). After curing, it was set aside. Subsequently, 1 wt% polyvinylpyrrolidone K-90 (PVPK-90), 3 wt% poloxamer 407 (P407), 10 wt% photoinitiator 6976, and 86 wt% deionized water were added to a beaker and magnetically stirred at 80 °C for 30 min; the obtained solution was sprayed on the TPU nanofiber membrane and irradiated with ultraviolet light for 4 min to obtain the hydrophilic layer 120.

[0096] The double-layer composite fiber membrane was peeled off from the silicon wafer to obtain a flexible substrate 100.

[0097] S2. Preparation of the microchannel layer 200 The molds of the microchannel layer were designed and optimized through software such as SolidWorks and Fluent to obtain a micro-needle patch model and an aggregation layer model. The models were imported into a 3D printing platform to fabricate physical molds to obtain a micro-needle patch mold and an aggregation layer mold; the PDMS solution and the curing agent were mixed at a mass ratio of 10:1 and magnetically stirred for 20 min to obtain a PDMS precursor solution with a total mass of 11 g. A part of the PDMS precursor solution was mixed and stirred evenly with ferromagnetic particles to obtain a PDMS / ferromagnetic particle mixture.

[0098] The steps for preparing the micro-needle patch 210 specifically include: spraying a release agent on the surface of the micro-needle patch mold and standing for 5 min. Then, the PDMS / ferromagnetic particle mixture was dropped onto the micro-needle patch mold. A neodymium iron boron magnet was placed under the mold. After the mixture filled the fine structures of the mold under the action of the magnetic force, it was cross-linked at 150 °C for 2 h, cooled, and demolded to obtain the micro-needle patch 210.

[0099] The steps for preparing the aggregation layer 220 specifically include: spraying a release agent on the surface of the aggregation layer mold and standing for 5 min. Then, the PDMS precursor was dropped onto the aggregation layer mold and left for 10 min to wait for the bubbles to disappear. Then, it was placed in a drying oven and baked at 90 °C for 2 h to cure, and demolded to obtain the aggregation layer 220.

[0100] So far, the microchannel layer 200 is prepared.

[0101] S3. Prepare the detection electrode 300 The steps to obtain the electrode deposition layer 310 specifically include: Using ultrasonic-assisted technology, 0.01 g of GO powder is uniformly dissolved in 2 g of dimethylacetamide solvent, and then 0.9 g of TPU particles are added and magnetically stirred for 3 h to obtain a GO / TPU composite precursor solution. The obtained solution is used to prepare a nanofiber membrane with a personalized pattern on a silicon wafer through electrostatic direct writing technology; Electrostatic direct writing parameter settings: direct writing voltage 2 kV, liquid supply rate 150 μL / h, direct writing distance 1.5 cm.

[0102] The steps to prepare the signal transmission wire 320 specifically include: Select copper cardboard as the transfer substrate and coat liquid metal on its surface; The coated substrate is dried. The liquid metal is transferred from the substrate to the surface of the electrode deposition layer 310 by mechanical pressure to form a patterned liquid metal. When the liquid metal penetrates into the electrode deposition layer 310, the signal transmission wire 320 is prepared; It should be noted that due to the wetting property of the electrode deposition layer to liquid metal, the liquid metal will penetrate into the pores of the electrode deposition layer, and the sensing electrode 330 does not have the wetting property to liquid metal. Therefore, the liquid metal only exists in the pores of the electrode deposition layer 310 and does not affect the sensing electrode 330 located on the surface of the electrode deposition layer 310.

[0103] The steps to prepare the sensing electrode 330 on the electrode deposition layer 310 specifically include: Combined with the mask template screen printing process on the electrode deposition layer 310, Ag / AgCl ink is printed to prepare a reference electrode, and conductive carbon paste is printed to prepare a counter electrode and a working electrode respectively. The PEDOT:PSS solution is mixed with an appropriate amount of dopant (such as PSSNa), and the mixed PEDOT:PSS solution is dropped on the surface of the working electrode that has been cleaned and plasma-treated, and spin coating (spin coating at 9000 rpm for 40 s) or drop coating is used for modification. After spin coating or drop coating is completed, the electrode is placed on a constant temperature hot stage at 160 °C for annealing for 15 min to form a uniform thin film.

[0104] S4. The steps to prepare the evaporation layer 400 specifically include: Dissolve 10 g of PAN particles in 85 g of DMF solvent, then add 5 g of inorganic filler particles, and magnetically stir for 2 h to obtain a PAN precursor. At room temperature, electrospin the PAN precursor on the upper plane of the aggregation layer 220 with an electrospinning voltage of 20 kV, a feeding rate of 300 μL / h, and a spinning distance of 15 cm. Then, every 15 minutes, the voltage is reduced by 3 kV. In this way, a multi-scale fiber membrane with a gradually increasing fiber diameter from bottom to top can be obtained, that is, the evaporation layer 400 is prepared.

[0105] S5. Assembly of the flexible substrate 100, the microchannel layer 200, the detection electrode 300, and the evaporation layer 400 According to Figure 1 the vertical distribution shown in the figure, combine them. Use the PDMS precursor solution obtained in step S1 as an adhesive and evenly dot it on the connection surfaces of each component. Place it in a drying oven and bake at 90 °C for 2 h until completely cured to obtain a sweat in-situ detection sensor.

[0106] 3. Performance experiment: (1) Cyclic voltammetry test of the sensor Use the prepared sweat in-situ sensor to perform cyclic voltammetry tests on solutions with different glucose concentrations, and take the peak current for result fitting.

[0107] The results are the same as those in Example 1, which proves that by using different steps to prepare the microchannel layer, the peak current of the prepared sweat in-situ detection sensor can also preferably reflect the glucose concentration situation and achieve the effect of sweat detection.

[0108] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection scope of the present application.

Claims

1. A sweat in-situ detection sensor based on a microneedle patch, characterized in that: include: A flexible substrate (100), wherein the flexible substrate (100) comprises: A hydrophobic layer (110), configured to contact the skin; A hydrophilic layer (120), the hydrophilic layer (120) being disposed on the hydrophobic layer (110), the sweat contact angle of the hydrophilic layer (120) being smaller than the sweat contact angle of the hydrophobic layer (110); A microchannel layer (200), wherein the microchannel layer (200) comprises: A microneedle patch (210), wherein the microneedle patch (210) is disposed on a side of the hydrophilic layer (120) facing away from the hydrophobic layer (110); An aggregation layer (220), the aggregation layer (220) being disposed on a side of the microneedle patch (210) facing away from the hydrophilic layer; A detection electrode (300), the detection electrode (300) being arranged between the aggregation layer (220) and the microneedle patch (210); The volatile layer (400) is arranged on a side of the aggregation layer (220) facing away from the microneedle patch (210).

2. The sweat in-situ detection sensor according to claim 1, characterized in that: The microneedle patch (210) comprises: Patch body (211); A plurality of openings (212) are formed through the patch body (211); a plurality of conical structures (213), each of which is located in each of the openings (212); a channel is provided between the conical structure (213) and the inner wall of the opening (212); the conical structure (213) protrudes toward the hydrophilic layer (120) and contacts the hydrophilic layer (120); The connection structure (214) is located in the opening (212) and is respectively connected to the conical structure (213) and the patch body (211).

3. The sweat in-situ detection sensor according to claim 2, characterized in that: The conical structure (213) comprises any axial longitudinal section that includes or is parallel to the central axis, the outer contour line of the axial longitudinal section forms a continuous curvature gradient from the top to the bottom, and the curvature of any point on the outer contour line gradually decreases from the top to the bottom; The conical structure (213) comprises an arbitrary radial cross section perpendicular to the central axis, the outer contour line of the radial cross section is an elliptical curve having a major diameter and a minor diameter, a continuous curvature gradient is formed in the direction from the major diameter endpoint to the minor diameter endpoint, and the curvature of any point on the outer contour of the radial cross section gradually decreases from the major diameter endpoint to the minor diameter endpoint.

4. The sweat in-situ detection sensor according to claim 3, characterized in that: The opening (212) is in a truncated cone-shaped structure, and the diameter of the circular cross-section of the opening (212) close to the hydrophilic layer (120) is larger than the diameter of the circular cross-section of the opening (212) close to the aggregation layer (220); The cone structure (213) has a vertex angle corresponding to an end point of the short diameter of the radial cross section of 3° to 15°; The aspect ratio of the radial cross section is 1.5 to 2.5:

1.

5. The sweat in-situ detection sensor according to claim 3, characterized in that: There are two connection structures (214), which are arranged opposite to each other in the area between the end point where the long diameter of the radial cross section is located and the inner wall of the opening (212).

6. The sweat in-situ detection sensor according to claim 1, characterized in that: The gathering layer (220) comprises: A concave conical channel (221), the concave conical channel (221) being arranged on a side of the aggregation layer (220) close to the microneedle patch (210) and aligned with the array of conical structures (213); A receiving groove (222), the receiving groove (222) and the concave tapered pipe (221) are located on the same side of the gathering layer (220), and are used to receive the detection electrode (300).

7. The sweat in-situ detection sensor according to claim 6, characterized in that: The radius of the semicircular cross section of the concave tapered pipe (211) gradually decreases from an end away from the containing groove (222) to an end close to the containing groove.

8. The sweat in-situ detection sensor according to claim 1, characterized in that: The detection electrode (300) comprises an electrode deposition layer (310), a signal transmission wire (320) and a sensing electrode (330); The signal transmission wire (320) and the sensing electrode (330) are arranged on the surface of the electrode deposition layer (310).

9. A method for preparing a sweat in-situ detection sensor according to any one of claims 1 to 8, characterized in that: The following steps are involved: The steps of preparing the flexible substrate (100) include: A uniform nanofiber film is deposited on a silicon wafer to obtain a hydrophobic layer (110); Depositing a uniform nanofiber membrane on the hydrophobic layer (110), and coating a hydrophilic polymer on the surface of the nanofiber membrane to obtain a hydrophilic layer (120); The preparation steps of the microchannel layer (200) include: Designing a microneedle patch model, preparing a microneedle patch mold according to the microneedle patch model, pouring a matrix material into the microneedle patch mold, and obtaining a microneedle patch (210); Designing a gathering layer model, preparing a gathering layer mold according to the gathering layer model, pouring a base material into the gathering layer mold, and obtaining a gathering layer (220); The preparation steps of the detection electrode (300) include: Depositing a uniform nanofiber film on a silicon wafer to obtain an electrode deposition layer (310); Preparing a signal transmission wire (320) and a sensing electrode (330) on the electrode deposition layer (310); The steps of preparing the volatile layer (400) include: Depositing a nanofiber membrane on the aggregation layer (220), and coating a hydrophilic polymer on a side of the nanofiber membrane away from the aggregation layer (220) to obtain a volatile layer (400); The flexible substrate (100), the microchannel layer (200), the detection electrode (300), and the volatile layer (400) are combined to prepare a sweat in-situ detection sensor.

10. The preparation method according to claim 9, characterized in that: The preparation method specifically comprises: A uniform TPU nanofiber membrane was prepared on a silicon wafer by an electrospinning process to obtain a hydrophobic layer (110); A uniform PAN nanofiber membrane is prepared on the hydrophobic layer (110) by an electrospinning process, and a hydrophilic polymer PVP is coated on the surface of the PAN nanofiber membrane to obtain a hydrophilic layer (120); A microneedle patch model is obtained, a microneedle patch mold is prepared according to the microneedle patch model, and then pre-prepared polydimethylsiloxane (PDMS) is poured into the microneedle patch mold, and after curing, the mold is demoulded to obtain a microneedle patch (210); Obtaining an aggregation layer model, preparing an aggregation layer mold according to the aggregation layer model, then pouring pre-prepared polydimethylsiloxane (PDMS) into the aggregation layer mold, and demoulding after curing to obtain an aggregation layer (220); A thermoplastic graphene oxide / TPU composite nanofiber membrane is prepared on a silicon wafer by an electrostatic direct writing process to obtain an electrode deposition layer (310); Forming a patterned liquid metal on the electrode deposition layer (310) through a transfer process to obtain a signal transmission wire (320); Preparing a sensing electrode (330) on the electrode deposition layer (310) by a screen printing process, wherein the sensing electrode (330) comprises a working electrode, a counter electrode, and a reference electrode; A uniform PAN nanofiber membrane is prepared on the upper surface of the aggregation layer (220) by an electrospinning process, and a volatile layer (400) is obtained by coating a hydrophilic polymer on a side of the PAN nanofiber membrane away from the aggregation layer (220); Among them, the TPU nanofiber membrane, PAN nanofiber membrane, and thermoplastic graphene oxide / TPU composite nanofiber membrane can all regulate the fiber diameter and pores by adjusting parameters such as electrospinning electric field intensity, nozzle distance, solution supply flow rate, and fiber stacking density.

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