A sweat in-situ detection sensor based on a microneedle patch and a preparation method thereof

Abstract

The application discloses a kind of sweat in-situ detection sensor based on microneedle patch and preparation method thereof, belong to sweat detection technical field.The sweat in-situ detection sensor includes: flexible substrate, flexible substrate includes: hydrophobic layer, for being contacted with skin;Hydrophilic layer, hydrophilic layer is set on hydrophobic layer, and the sweat contact angle of hydrophilic layer is less than the sweat contact angle of hydrophobic layer;Microchannel layer, microchannel layer includes: microneedle patch, microneedle patch is set on the side of hydrophilic layer away from hydrophobic layer;Aggregation layer, aggregation layer is set on the side of microneedle patch away from hydrophilic layer;Detection electrode, detection electrode is set between aggregation layer and microneedle patch;Volatile layer, set on the side of aggregation layer away from microneedle patch, can solve the sweat utilization rate of current wearable sweat detection sensor is not saturated, sweat accumulation backflow, trace amount of sweat is difficult to be fully utilized, affect physiological signal detection precision and other problems, with huge application potential.

Description

TECHNICAL FIELD

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

[0002] The biomarkers in human sweat can be used for physiological health detection analysis. As a large number of clinical tests have proved, the sweat glucose content can be used as a daily monitoring index for diabetic patients, and the sweat uric acid index can reflect the purine intake and be used for gout prevention. Compared with the detection of other body fluids (such as blood, saliva, etc.), sweat detection not only has the advantages of non-invasiveness and non-invasiveness, but also has a wider variety of biomarkers. 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 complicated detection process of traditional sweat detection technology. The sweat collection, transportation and detection analysis are integrated on the skin surface, which is an important development direction in the future.

[0003] However, some existing sweat in-situ detection sensors can guide the directional transportation of sweat by using the hydrophilic-hydrophobic difference of Janus membrane, but ignore the balance between the evaporation rate of sweat and the transportation rate of sweat. When the amount of sweat suddenly increases (in hot, intense exercise, etc.), the evaporation amount of sweat is less than the secretion amount, which will cause the accumulation of sweat and induce the backflow of sweat.

[0004] In addition, some sweat in-situ sensors also have the problems that the trace amount of sweat is difficult to be fully utilized, affecting the detection accuracy of physiological signals, or the preparation process is very complex (such as involving photolithography, laser treatment). SUMMARY

[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 at least solve one of the problems existing in the prior art, so as to realize the one-way transportation of sweat, prevent the backflow of sweat and improve the utilization rate of sweat.

[0006] In order to solve the above technical problems, the present application is implemented as follows:

[0007] In a first aspect, the embodiments of the present application provide a sweat in-situ detection sensor based on a microneedle patch, comprising:

[0008] A flexible substrate, the flexible substrate comprising:

[0009] A hydrophobic layer for contacting the skin;

[0010] A hydrophilic layer, the hydrophilic layer being arranged on the hydrophobic layer, and the sweat contact angle of the hydrophilic layer being smaller than the sweat contact angle of the hydrophobic layer;

[0011] A microchannel layer, the microchannel layer comprising:

[0012] The microneedle patch is arranged on the side of the hydrophilic layer away from the hydrophobic layer;

[0013] The aggregation layer is arranged on the side of the microneedle patch away from the hydrophilic layer;

[0014] The detection electrode is arranged between the aggregation layer and the microneedle patch;

[0015] The volatile layer is arranged on the side of the aggregation layer away from the microneedle patch.

[0016] Further, the microneedle patch comprises:

[0017] The patch body;

[0018] A plurality of openings are arranged on the patch body;

[0019] A plurality of tapered structures are respectively arranged in each opening, and a short channel is formed between the tapered structure and the inner wall of the opening. The tapered structure protrudes towards the hydrophilic layer and is in contact with the hydrophilic layer;

[0020] The adapter structure is arranged in the opening and connected to the tapered structure and the patch body respectively.

[0021] Further, the tapered structure comprises an arbitrary axial longitudinal section containing or parallel to the central axis, and the outer contour line of the axial longitudinal section forms a continuous curvature gradient from the top to the bottom. The curvature of any point on the outer contour line gradually decreases from the top to the bottom;

[0022] The tapered structure comprises an arbitrary radial cross section perpendicular to the central axis, and the outer contour line of the radial cross section is an elliptical curve with a major axis and a minor axis. A continuous curvature gradient is formed in the direction from the major axis end point to the minor axis end point. The curvature of any point on the outer contour line of the radial cross section gradually decreases from the major axis end point to the minor axis end point.

[0023] Further, the opening has a circular truncated cone structure, and the diameter of the circular cross section on the side close to the hydrophilic layer is greater than the diameter of the circular cross section on the side close to the aggregation layer;

[0024] The corresponding top angle of the tapered structure at the minor axis end point of the radial cross section is 3°-15°;

[0025] The ratio of the major axis to the minor axis of the radial cross section is 1.5-2.5:1.

[0026] Further, the adapter structure is two, and is arranged in the region between the inner walls of the openings containing the end points of the major axis of the radial cross section.

[0027] Further, the aggregation layer comprises:

[0028] The concave tapered pipeline is arranged on the side of the aggregation layer close to the microneedle patch, and is aligned with the array of tapered structures;

[0029] The accommodation groove is on the same side of the aggregation layer as the concave conical pipeline, and is used for accommodating the detection electrode.

[0030] Further, the radius of the semicircular cross section of the concave conical pipeline gradually decreases from an end far away from the accommodation groove to an end close to the accommodation groove.

[0031] Further, the detection electrode comprises 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.

[0032] In a second aspect, the application discloses a preparation method of a sweat in-situ detection sensor, comprising the following steps:

[0033] The preparation step of the flexible substrate comprises:

[0034] A uniform nanofiber film is deposited on the silicon wafer to obtain the hydrophobic layer;

[0035] A uniform nanofiber film is deposited on the hydrophobic layer, and a hydrophilic polymer is coated on the surface of the nanofiber film to obtain the hydrophilic layer;

[0036] The preparation step of the microchannel layer comprises:

[0037] A microneedle patch model is designed, a microneedle patch mold is prepared according to the microneedle patch model, a base material is poured into the microneedle patch mold, and the microneedle patch is obtained.

[0038] An aggregation layer model is designed, an aggregation layer mold is prepared according to the aggregation layer model, a base material is poured into the aggregation layer mold, and the aggregation layer is obtained.

[0039] The preparation step of the detection electrode comprises:

[0040] A uniform nanofiber film is deposited on the silicon wafer to obtain the electrode deposition layer;

[0041] The signal transmission wire and the sensing electrode are prepared on the electrode deposition layer;

[0042] The preparation step of the volatile layer comprises:

[0043] A nanofiber film is deposited on the aggregation layer, and a hydrophilic polymer is coated on the side of the nanofiber film far away from the aggregation layer to obtain the volatile layer;

[0044] The sweat in-situ detection sensor is prepared by combining the flexible substrate, the microchannel layer, the detection electrode and the volatile layer.

[0045] Further, the preparation method specifically comprises:

[0046] A uniform TPU nanofiber film is prepared on the silicon wafer by an electrospinning process to obtain the hydrophobic layer;

[0047] A uniform PAN nanofiber membrane is prepared on the hydrophobic layer by an electrospinning process, and a hydrophilic polymer PVP is coated on the surface of the PAN nanofiber membrane to obtain a hydrophilic layer;

[0048] A microneedle patch model is designed, a microneedle patch film is prepared according to the microneedle patch model, then the pre-prepared polydimethylsiloxane is poured into the microneedle patch mold, and the microneedle patch is obtained after curing and demolding;

[0049] An aggregation layer model is designed, an aggregation layer film is prepared according to the aggregation layer model, then the pre-prepared polydimethylsiloxane is poured into the aggregation layer mold, and the aggregation layer is obtained after curing and demolding;

[0050] 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;

[0051] A patterned liquid metal is formed on the electrode deposition layer by a transfer process to obtain a signal transmission wire;

[0052] A sensing electrode is prepared on the electrode deposition layer by a screen printing process, and the sensing electrode includes a working electrode, a counter electrode and a reference electrode;

[0053] A uniform PAN nanofiber membrane is prepared on the surface of the aggregation layer by an electrospinning process, and a hydrophilic polymer is coated on the side of the PAN nanofiber membrane away from the aggregation layer to obtain a volatile layer;

[0054] The TPU nanofiber membrane, the PAN nanofiber membrane and the thermoplastic graphene oxide / TPU composite nanofiber membrane can all be adjusted in fiber diameter and porosity by adjusting electrospinning field strength, nozzle distance, solution supply flow rate and fiber packing density.

[0055] The present application at least includes the following beneficial effects:

[0056] (1) The present application ingeniously designs a double-dimensional gradient conical surface structure, which can spontaneously move upward and avoid the obstruction of the channel joint structure, realize directional transport, improve the utilization rate of sweat, and ensure the detection accuracy of physiological signals.

[0057] (2) The recessed conical pipeline of the aggregation layer designed in the present application can drive sweat to spontaneously collect to the detection electrode arranged in the aggregation layer containing groove.

[0058] (3) The present application uses a multi-scale structure nanofiber membrane as a volatile layer to timely discharge the measured sweat, maintain the balance between sweating and perspiration, and improve the accuracy of sweat detection.

[0059] (4) Simple preparation, without involving expensive and time-consuming processes such as photolithography and sputtering. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 A structure schematic diagram of a sweat in-situ detection sensor based on a microneedle patch provided by an embodiment of the present application.

[0061] Figure 2 A schematic diagram of an axial longitudinal section of a conical structure provided by an embodiment of the present application.

[0062] Figure 3 A schematic diagram of a radial cross section of a conical structure provided by an embodiment of the present application.

[0063] Figure 4 A local structure diagram of a microneedle patch provided by an embodiment of the present application.

[0064] Figure 5 A local structure diagram of an aggregation layer provided by an embodiment of the present application.

[0065] Figure 6 A diagram of a single pipeline in an aggregation layer provided by an embodiment of the present application.

[0066] Figure 7 A flowchart of a preparation method of a sweat in-situ detection sensor based on a microneedle patch provided by an embodiment of the present application.

[0067] Figure 8 A schematic diagram of a sweat transport path provided by an embodiment of the present application.

[0068] Figure 9 A simulation result diagram of different vertex angles of a single microneedle unit of a microneedle patch provided by Embodiment 1 of the present application.

[0069] Figure 10 A simulation result diagram of different length-diameter ratios of a single microneedle unit of a microneedle patch provided by Embodiment 1 of the present application.

[0070] Figure 11 A liquid directional transport experiment diagram of an aggregation layer provided by Embodiment 1 of the present application.

[0071] Figure 12 A linear fitting curve diagram of a peak current and a glucose concentration obtained by detection provided by Embodiment 1 of the present application.

[0072] Reference signs:

[0073] 100, flexible substrate; 110, hydrophobic layer; 120, hydrophilic layer;

[0074] 200, microchannel layer; 210, microneedle patch; 211, patch body; 212, opening; 213, conical structure; 214, connection structure; 220, aggregation layer; 221, concave conical pipeline; 222, accommodating groove;

[0075] 300, detection electrode; 310, electrode deposition layer; 320, signal transmission wire; 330, sensing electrode;

[0076] 400, volatile layer. DETAILED DESCRIPTION

[0077] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0078] The present application provides a sweat in-situ detection sensor based on a microneedle patch, as shown in the figure, the detection sensor comprises: Figure 1

[0079] a flexible substrate 100, the flexible substrate 100 comprises:

[0080] a hydrophobic layer 110 for contacting the skin;

[0081] a hydrophilic layer 120, the hydrophilic layer 120 is arranged on the hydrophobic layer 110, and the sweat contact angle of the hydrophilic layer 120 is less than the sweat contact angle of the hydrophobic layer 110.

[0082] It is worth noting that the flexible substrate 100 is prepared by layer-by-layer deposition of nanofiber membranes by electrospinning process, which has high flexibility and can conform to the skin, the porous structure has good permeability and is convenient for fluid to pass through, the hydrophobic layer 110 has hydrophobicity to sweat, and direct attachment 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 less than the sweat contact angle of the hydrophobic layer 110, which can guide the hydrophobic layer 110 to transport the sweat along the fibers of the nanofiber membrane to the hydrophilic layer 120.

[0083] a microchannel layer 200, the microchannel layer 200 comprises:

[0084] a microneedle patch 210 arranged on the side of the hydrophilic layer 120 away from the hydrophobic layer 110;

[0085] an aggregation layer 220 arranged on the side of the microneedle patch 210 away from the hydrophilic layer;

[0086] In this embodiment, the microneedle patch 210 is located between the hydrophilic layer 120 and the aggregation layer 220, which can further transport the sweat of the hydrophilic layer 120 to the aggregation layer 220, realizing directional transportation of sweat without backflow.

[0087] In some embodiments of the present application, the microneedle patch 210 comprises:​

[0088] patch body 211;

[0089] a plurality of openings 212 disposed on the patch body 211;

[0090] a plurality of tapered structures 213 respectively disposed in each of the openings 212, the tapered structure 213 having a passage between the inner wall of the opening 212 and the tapered structure 213, the tapered structure 213 protruding towards the hydrophilic layer 120 and being in contact with the hydrophilic layer 120;

[0091] an adapter structure 214 disposed in the opening 212 and connected to the tapered structure 213 and the patch body 211 respectively.

[0092] Further, as shown in Figure 2 the tapered 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;

[0093] As shown in Figure 3 the tapered 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 having a major axis and a minor axis, and a continuous curvature gradient is formed in the direction from the major axis end point to the minor axis end point, and the curvature of any point on the outer contour line of the radial cross section gradually decreases from the major axis end point to the minor axis end point.

[0094] It is worth noting that the top is a region where the axial curvature radius R of the tapered structure 213 is smaller, and the bottom is a region where the axial curvature radius R of the tapered structure 213 is larger, Figure 2 B_B refers to Figure 3 the position of the radial cross section. Figure 2

[0095] The major axis end point and the minor axis end point are the major axis and the minor axis of the outer contour line of any radial cross section and the intersection point of the elliptical circumference (outer contour line).

[0096] The two-dimensional (i.e. axial and radial) curvature gradient characteristics of the tapered structure can allow the tapered structure 213 to transport sweat in a specific direction, and the two can work together to achieve automatic avoidance of sweat by the adapter structure, thereby improving sweat utilization and ensuring no backflow.

[0097] The specific analysis process of the two-dimensional curvature gradient characteristics for directing the transport of sweat by Laplace pressure is as follows:

[0098] The axial tapered structure causes the curvatures on both sides of the sweat to be different due to the convex tapered surface, 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: ​

[0099] The Laplace pressure of the sweat in any axial longitudinal section is:

[0100] P= (1-1)

[0101] 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 of each component of the sweat is obtained as:

[0102] + )(1-2)

[0103] Assuming that the radius r of the sweat (spherical surface) does not change with x, i.e. =0, then:

[0104] (1-3)

[0105] In the xy coordinate system, R=tanα*x (x is the axial variable, and α is the conical vertex angle), i.e.

[0106] α(1-4)

[0107] Substituting formula (4) into formula (3) gives:

[0108] α(1-5)

[0109] The above formula is rewritten as:

[0110] αdx(1-6)

[0111] Therefore, the Laplace pressure difference of the sweat on both sides of the conical structure is shown in the following formula:

[0112] ΔP= (1-7)

[0113] Therefore, the Laplace pressure difference depends on the corresponding vertex angle α at the short diameter end point of the outer contour line of any radial cross section (which has been verified by simulation in Example 1).

[0114] Since the Laplace pressure of the sweat at the top end region is greater than that at the bottom region, the pressure difference inside the sweat drives the sweat to move from the top end to the bottom.

[0115] The radial elliptical cross section also uses the Laplace pressure difference to drive the sweat to gather to the small curvature, and the specific analysis process is as follows:

[0116] The major axis of the ellipse is a, and the minor axis is b. To simplify the calculation, a and b are scaled proportionally, and we assume that b=1, a=k, and b=k.

[0117] According to the Laplace pressure formula:

[0118] ΔP=γ( (1-8)

[0119] Where K is the radius of curvature of the infinitesimal element. In this model, , ,

[0120] Then we have: ΔP = (1-9)

[0121] Differentiating the Laplace pressure in its x-direction, the Laplace pressure on each component of sweat is:

[0122] + (1-10)

[0123] Assuming the radius r (circle of cross-section) of the sweat does not change with x, i.e. =0, then:

[0124] (1-11)

[0125] According to the formula for the radius of an ellipse at any point:

[0126] R= (1-12)

[0127] Substituting formula (12) into formula (11) yields:

[0128] = * * *( (1-13)

[0129] Taking the first derivative of the ellipse equation with respect to x, we get:

[0130] = (1-14)

[0131] Substituting formula (14) into formula (13) yields:

[0132] = * * *( (1-15)

[0133] Therefore, the Laplace pressure difference generated by sweat in a radially elliptical cross section is shown in the following formula:

[0134] ΔP= * *( )dx(1-16)

[0135] Where y is a function of x, the Laplace pressure difference depends on the ratio k of a to b (as confirmed by simulation in Example 1), the outer contour of any radial cross section is an elliptical curve with a major axis and a minor axis, forming a continuous curvature gradient in the direction from the endpoint of the major axis to the endpoint of the minor axis, and 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 endpoint of the major axis is greater than the curvature radius R at the endpoint of the minor axis. The pressure difference inside the sweat drives the sweat to move towards the generatrix with smaller curvature.

[0136] Furthermore, the opening 212 has a frustum-shaped structure, and the diameter of the circular cross-section of the opening 212 on the side closer to the hydrophilic layer 120 is larger than the diameter of the circular cross-section on the side closer to the aggregation layer 220.

[0137] The apex angle of the tapered structure 213 at the end of the minor axis of the radial cross section is 3°~15°;

[0138] The radial cross-section has a length-to-minor-diameter ratio of 1.5 to 2.5:1.

[0139] like Figure 4 As shown, in some embodiments, simulation experiments have revealed that the transport efficiency is highest when the apex angle corresponding to the endpoint of the short diameter of the radial cross-section is 8°, and the amount of sweat film formed is the least when the ratio of the length to the short diameter of the radial cross-section is 1.8:1, resulting in the best transport effect.

[0140] It is worth noting that the opening 212 has a frustum-shaped structure, and the diameter of the circular cross-section of the opening 212 near the hydrophilic layer 120 is larger than the diameter of the circular cross-section near the aggregation layer 220. This allows the channel between the conical structure 213 and the inner wall of the opening 212 to provide clearance for the directional transport of sweat, while its inner surface also has a curvature gradient change. This, along with the outer surface of the conical structure, can provide driving force, further propelling the sweat to move directionally to the aggregation layer.

[0141] Furthermore, there are two connecting structures 214, which are disposed opposite to each other in the area between the inner walls of the openings 212 at the ends of the radial cross-section major diameters.

[0142] like Figure 5 As shown, the aggregation layer 220 includes:

[0143] Concave conical duct 221, which is arranged on the side of the gathering layer 220 close to the microneedle patch 210 and is aligned with the array of conical structures 213;

[0144] Accommodation groove 222, which is arranged on the same side of the gathering layer 220 as the concave conical duct 221, is used to accommodate the detection electrode 300.

[0145] Further, as shown in the figure, the radius of the semicircular cross section of the concave conical duct 221 gradually decreases from the end away from the central area of the gathering layer to the end close to the central area of the gathering layer. Figure 6

[0146] It is worth noting that the concave conical duct 221 is aligned with the array of conical structures 213 on the microneedle patch, and the sweat is collected to the central area where the detection electrode is located under the cooperation of the duct structure and the microneedle patch, thus completing the process of sweat collection.

[0147] Further, the detection electrode 300 is arranged between the gathering layer 220 and the microneedle patch 210.

[0148] 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 arranged on the surface of the electrode deposition layer 310.

[0149] 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, in which the reference electrode is Ag / AgCl ink, the counter electrode is conductive carbon paste, and the working electrode is conductive carbon paste (with glucose oxidase).

[0150] Further, the volatilization layer 400 is arranged on the side of the gathering layer 220 away from the microneedle patch 210 and is prepared by layer-by-layer deposition of nanofiber membranes by electrospinning process. The porous structure and the longitudinal wettability gradient characteristics can timely discharge the measured sweat, and adjusting the fiber structure can optimize the sweat volatilization, so as to ensure more sufficient detection and improve the detection sensitivity.

[0151] The present application discloses a preparation method of a sweat in-situ detection sensor, as shown in the figure Figure 7 The method comprises the following steps:

[0152] Preparation steps of the flexible substrate 100:

[0153] A uniform TPU nanofiber membrane is prepared on a silicon wafer by electrospinning process to obtain the hydrophobic layer 110.

[0154] ​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;

[0155] The preparation steps of the microchannel layer 200 are as follows:

[0156] A microneedle patch model is designed, a microneedle patch mold is prepared according to the microneedle patch model, and then the pre-prepared polydimethylsiloxane (PDMS) is poured into the microneedle patch mold, and the microneedle patch 210 is obtained after curing and demolding.

[0157] An aggregation layer model is designed, an aggregation layer mold is prepared according to the aggregation layer model, and then the pre-prepared polydimethylsiloxane (PDMS) is poured into the aggregation layer mold, and the aggregation layer 220 is obtained after curing and demolding.

[0158] The preparation steps of the detection electrode 300 are as follows:

[0159] 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.

[0160] A patterned liquid metal is formed on the electrode deposition layer 310 by a transfer printing process to obtain a signal transmission wire 320.

[0161] A sensing electrode 330 is prepared on the electrode deposition layer 310 by a screen printing process, and the sensing electrode 330 includes a working electrode, a counter electrode, and a reference electrode.

[0162] The preparation steps of the volatile layer 400 are as follows:

[0163] A uniform PAN nanofiber membrane is prepared on the surface of the aggregation layer 220 by an electrospinning process, and a hydrophilic polymer is coated on the side of the PAN nanofiber membrane away from the aggregation layer 220 to obtain the volatile layer 400.

[0164] The TPU nanofiber membrane, the PAN nanofiber membrane, and the thermoplastic graphene oxide / TPU composite nanofiber membrane can all be adjusted by adjusting the electrospinning electric field strength, the nozzle distance, the solution supply flow rate, and the fiber packing density to control the fiber diameter and the porosity.

[0165] The flexible substrate 110, the microchannel layer 200, the detection electrode 300, and the volatile layer 400 are combined to prepare a sweat in-situ detection sensor.

[0166] As Figure 8As shown, the present application uses a combination of microneedle patches and nanofibers to construct a sweat in-situ detection sensor. Sweat, under the secretion pressure of sweat glands, directly contacts the hydrophobic layer 110. Due to the wetting gradient and capillary force between the hydrophobic layer 110 and the upper hydrophilic layer 120, sweat self-permeates to the hydrophilic layer 120, ensuring that there is no residual epidermal sweat. The microneedle patch 210 on the upper layer of the hydrophilic layer 120 has a double-gradient conical structure 230. The Laplace pressure difference exists in the radial and axial directions of the conical structure, spontaneously moving upward and avoiding the obstruction at the short channel junction, realizing directional transport while improving the utilization rate of sweat, and ensuring the detection accuracy of physiological signals. The recessed conical pipeline 221 of the aggregation layer can drive sweat to spontaneously converge to the detection electrode 300 arranged in the aggregation layer containing groove, and 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 the stability of signal transmission under deformation interference. Moreover, the sweat in-situ detection sensor prepared by the present application is simple to prepare as a whole and does not involve expensive and time-consuming processes such as photolithography and sputtering.

[0167] The present application will be further described in detail below with specific examples, but the present application is not limited to the following specific examples.

[0168] Example 1

[0169] 1. The present example provides a sweat in-situ detection sensor based on a microneedle patch, which comprises:

[0170] A flexible substrate 100, which comprises:

[0171] A hydrophobic layer 110, which is prepared from a thermoplastic TPU composite nanofiber membrane, is mutually exclusive with sweat and does not exhibit wetting behavior, with a sweat contact angle of 148°.

[0172] A hydrophilic layer 120, which is prepared by coating polyvinylpyrrolidone (PVP) on the surface of a PAN nanofiber membrane, has better wettability than the 11-hydrophobic layer, with a sweat contact angle of 14°.

[0173] A microchannel layer 200, which comprises:

[0174] A microneedle patch 210, which is prepared by molding a PDMS precursor, and the required mold is obtained by micro-nano 3D printing technology, with a microneedle tip angle of 8° and an elliptical cross-section aspect ratio of 1.8:1.

[0175] An aggregation layer 220, which is prepared by molding a PDMS precursor, and the required mold is obtained by micro-nano 3D printing technology,

[0176] The structure has a curvature gradient change characteristic, as shown.

[0177] The detection electrode 300 comprises:

[0178] The electrode deposition layer 310 is prepared from a thermoplastic graphene oxide / TPU composite nanofiber film of a personalized pattern structure, which has a wetting behavior to liquid metal with a contact angle of 26°.

[0179] The signal transmission wire 320 is prepared by patterned liquid metal transfer, wherein the liquid metal component is gallium: indium: tin with a mass ratio of 0.68:0.215:0.1 and a melting point of 11℃.

[0180] The sensing electrode 330 is a three-electrode system for glucose detection, comprising a working electrode, a counter electrode, and a reference electrode. The whole is prepared by screen printing process, wherein the reference electrode is Ag / AgCl ink, the counter electrode is conductive carbon paste, and the working electrode is conductive carbon paste (with glucose oxidase).

[0181] The volatile layer 440 is composed of a PAN composite nanofiber film, which has good wettability to sweat with a sweat contact angle of 14°.

[0182] 2. The preparation method of the sweat in-situ detection sensor of the present application comprises the following steps:

[0183] S1, preparing a flexible substrate 100

[0184] The step of preparing the hydrophobic layer 110 specifically comprises:

[0185] 10g of TPU particles are uniformly dispersed in 85g of DMF solvent by using ultrasonic assisted technology, and 5g of inorganic filler is added and uniformly stirred to obtain a TPU precursor solution. The obtained solution is uniformly deposited on a silicon wafer by electrospinning process to prepare a PAN nanofiber film, thereby obtaining the hydrophobic layer 110. The electrospinning voltage is 20kV, the liquid supply rate is 300μL / h, and the spinning distance is 15cm.

[0186] The step of preparing the hydrophilic layer 120 specifically comprises:

[0187] PAN particles are dissolved in DMF solvent. 10g of PAN particles are dissolved in 90g of DMF solvent, and magnetic stirring is performed for 2h to obtain a PAN precursor solution. The obtained solution is uniformly deposited on the hydrophobic layer by electrospinning process to prepare a PAN nanofiber film, and 40wt% of PVP is coated on the surface of the fiber film to prepare the hydrophilic layer 120. The electrospinning voltage is 20kV, the liquid supply rate is 300μL / h, and the spinning distance is 15cm.

[0188] The double-layer composite fiber film is peeled off from the silicon wafer to obtain the flexible substrate 100.

[0189] S2, preparing the microchannel layer 200

[0190] The mold of the microchannel layer is designed and optimized by software such as solidworks and Fluent to obtain a microneedle patch model and an aggregation layer model, and the model is imported into a 3D printing platform to make a mold physical object to obtain a microneedle patch mold and an aggregation layer mold; PDMS solution and curing agent are mixed in a mass ratio of 10:1, and magnetic stirring is performed for 20 min to obtain a total mass of 11 g of PDMS precursor solution, and a part of the PDMS precursor solution is mixed with the ferromagnetic particles to obtain a PDMS / ferromagnetic particle mixture.

[0191] The steps of preparing the microneedle patch 210 specifically include: spraying a release agent on the surface of the microneedle patch mold, standing for 5 min, adding the PDMS / ferromagnetic particle mixture to the microneedle patch mold, placing a neodymium iron boron under the mold, and after the mixture fills the small structure of the mold under the action of the magnetic field force, crosslinking at 150℃ for 2h, cooling and demolding to obtain the microneedle patch 210.

[0192] The steps of preparing the aggregation layer 220 specifically include: spraying a release agent on the surface of the aggregation layer mold, standing for 5 min, adding the PDMS precursor to the aggregation layer mold, standing for 10 min to wait for the bubbles to disappear, then placing it in a drying oven at 90℃ for 2h to cure, and demolding to obtain the aggregation layer 220.

[0193] S3, preparing the detection electrode 300

[0194] The steps of obtaining the electrode deposition layer 310 specifically include:

[0195] 0.01g of GO powder is uniformly dissolved in 2g of dimethylacetamide solvent by using ultrasonic assisted technology, then 0.9g of TPU particles are added and magnetically stirred for 3h to obtain a GO / TPU composite precursor solution. The obtained solution is used to prepare a personalized patterned nanofiber membrane on a silicon wafer by electrostatic direct writing technology; the electrostatic direct writing parameters are set as follows: direct writing voltage 2kV, liquid supply rate 150μL / h, and direct writing distance 1.5cm.

[0196] The steps of preparing the signal transmission wire 320 specifically include:

[0197] Copper paperboard is selected as a transfer substrate, and liquid metal is coated on the surface of the substrate; 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, and the signal transmission wire 320 is prepared after the liquid metal penetrates into the electrode deposition layer 310.

[0198] It is worth noting that, since the electrode deposition layer 310 has wetting properties for liquid metal, the liquid metal will penetrate into the pores of the electrode deposition layer. The sensing electrode 330 does not have wetting properties 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.

[0199] The specific steps for fabricating the sensing electrode 330 on the electrode deposition layer 310 include:

[0200] First, 60 mg of GO powder and 30 mg of glucose oxidase were fully dissolved in 36 mL of PBS buffer (0.1 mol / mL) to prepare a modified solution (33% enzyme content). Then, Ag / AgCl ink was printed on the electrode deposition layer 330 using a mask screen printing process to prepare a reference electrode. Conductive carbon paste was printed to prepare the counter electrode and working electrode, respectively. Then, the enzyme-containing modified solution was dropped onto the surface of the working electrode using a pipette. The electrode was dried at room temperature and the dropping was repeated 5 times to obtain the sensing electrode 330.

[0201] S4. The specific steps for preparing the volatile layer 400 include:

[0202] Dissolve 10g of PAN granules in 85g of DMF solvent, then add 5g of inorganic filler. The particles were magnetically stirred for 2 hours to obtain a PAN precursor. At room temperature, the PAN precursor was electrospun planarly on the aggregate layer 220 with an electrospinning voltage of 20 kV, a liquid supply rate of 300 μL / h, and a spinning spacing of 15 cm. The voltage was then reduced by 3 kV every 15 minutes to obtain a multi-scale fiber membrane with the fiber diameter gradually increasing from bottom to top. 40 wt% PVP was coated on the surface of the fiber membrane to obtain a PAN / PVP nanofiber membrane, which is the volatile layer 400.

[0203] Assembly of S5, flexible substrate 100, microchannel layer 200, detection electrode 300, and volatile layer 400

[0204] According to Figure 1 The components are arranged vertically as shown. The PDMS precursor solution obtained in step S2 is used as a binder and evenly applied to the joint surfaces of each component. The components are then placed in a drying oven at 90°C for 2 hours until fully cured to obtain the sweat in-situ detection sensor.

[0205] 3. Performance Experiment:

[0206] (1) Simulation test of conical structure

[0207] The microneedle patch 210 prepared in step S2 above was subjected to simulation test to detect the performance of the two-dimensional gradient cone structure of the microneedle patch 210. The cone structure apex angles of 4°, 8° and 14° were respectively used as three control groups.

[0208] The radial cross-section aspect ratio is 1.5:1, 1.8:1, and 2:1, respectively, as three groups of control groups.

[0209] (2) Aggregation layer aggregation effect test

[0210] Take black liquid drops on the end of the pipeline, observe and record the self-transportation state of the liquid drops at different times in time.

[0211] (3) Sensor cyclic voltammetry test

[0212] The prepared sweat in-situ sensor is used to test the cyclic voltammetry of solutions with different glucose concentrations, and the peak current is used for result fitting.

[0213] 4. Result analysis:

[0214] As shown in Figure 9 , it can be seen from the analysis of the simulation results that the top angle of 8° has the highest sweat transportation rate.

[0215] As shown in Figure 10 , it can be seen that when the radial cross-section aspect ratio is 1.8:1, the sweat film formation amount is small and the aggregation effect is best, which is more conducive to sweat transportation and obstacle avoidance (radial mainly responsible for concentrating sweat, avoiding joint structure), thereby more conducive to sweat transportation.

[0216] As shown in Figure 11 , it can be seen that the black liquid drops spontaneously move to the central area, and the concave tapered pipeline design of the aggregation layer has good aggregation effect.

[0217] As shown in Figure 12 , 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, thereby generating more electron transfer. These electron transfers form a current, so the glucose concentration is proportional to the peak current, and the peak current of the sensor can better reflect the concentration of glucose.

[0218] Example 2

[0219] 1. Another sweat in-situ detection sensor combining microneedle patch and nanofiber and a preparation method thereof are provided in this embodiment, and the sweat in-situ detection sensor comprises:

[0220] A flexible substrate 100, the flexible substrate 100 comprises:

[0221] A hydrophobic layer 110 is prepared from a thermoplastic TPU composite nanofiber membrane, which is mutually exclusive with sweat and does not have wetting behavior, and the sweat contact angle is 148°.

[0222] The hydrophilic layer 120 is prepared by modifying a thermoplastic TPU nanofiber membrane with ultraviolet light. The nanofiber membrane has better wettability to sweat than the hydrophobic layer 110, and the sweat contact angle is 70°.

[0223] The microchannel layer 200 includes:

[0224] The microneedle patch 210 is prepared by molding a PDMS precursor, and the required mold is obtained by micro-nano 3D printing technology. The microneedle tip angle is 8°, and the cross-sectional ellipse aspect ratio is 1.8.

[0225] The aggregation layer 220 is prepared by molding a PDMS precursor, and the required mold is obtained by micro-nano 3D printing technology. The structure has a curvature gradient change characteristic.

[0226] The detection electrode 300 includes:

[0227] The electrode deposition layer 310 is prepared from a thermoplastic graphene oxide / TPU composite nanofiber membrane with a personalized pattern structure. The TPU composite nanofiber membrane has a wetting behavior to liquid metal, and the contact angle is 26°.

[0228] The signal transmission wire 320 is prepared by patterned liquid metal transfer, and the liquid metal component is gallium: indium: tin with a mass ratio of 0.68:0.215:0.1, and the melting point is 11℃.

[0229] The sensing electrode 330 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 process, wherein the reference electrode is Ag / AgCl ink, the counter electrode is conductive carbon paste, and the working electrode is conductive carbon paste (with PEDOT modification material).

[0230] The volatile layer 400 is composed of a PAN composite nanofiber membrane, which has good wettability to sweat, and the sweat contact angle is 14°.

[0231] 2. The preparation method of the sweat in-situ detection sensor includes the following steps:

[0232] S1, preparing a flexible substrate 100

[0233] The step of preparing the hydrophobic layer 110 specifically includes:

[0234] Using ultrasonic assisted technology, 10g of TPU particles are uniformly dispersed in 85g of DMF solvent, and 5g of inorganic filler is added and stirred uniformly to obtain a TPU precursor solution. At room temperature, the obtained solution is prepared by electrospinning process to prepare the hydrophobic layer 110, wherein the electrospinning voltage is 20kV, the liquid supply rate is 300μL / h, and the spinning distance is 15cm.

[0235] The step of preparing the hydrophilic layer 120 specifically includes:

[0236] 10 g of TPU particles are uniformly dispersed in 85 g of DMF solvent by using ultrasonic auxiliary technology, and 5 g of inorganic filler is added and stirred uniformly to obtain a TPU precursor solution. The obtained solution is used for electrospinning on the hydrophobic layer 110 at room temperature (electrospinning voltage 20 kV, liquid supply rate 300 μL / h, and spinning distance 15 cm). After solidification, it is ready for use. 1 wt% polyvinylpyrrolidone K-90 (PVPK-90), 3 wt% poloxamer 407 (P407), 10 wt% photoinitiator 6976, and 86 wt% deionized water are sequentially added to a beaker and magnetically stirred at 80°C for 30 min. The obtained solution is sprayed on the TPU nanofiber membrane, and a hydrophilic layer 120 is prepared by irradiating with purple light for 4 min.

[0237] The double-layer composite fiber membrane is peeled off from the silicon wafer to obtain the flexible substrate 100.

[0238] S2, preparation of the microchannel layer 200

[0239] The mold of the microchannel layer is designed and optimized by software such as solidworks and Fluent to obtain a microneedle patch model and an aggregation layer model. The model is imported into a 3D printing platform to make a mold physical object to obtain a microneedle patch mold and an aggregation layer mold. The PDMS solution and the curing agent are mixed in a mass ratio of 10:1, magnetically stirred for 20 min to obtain a total mass of 11 g of PDMS precursor solution. A part of the PDMS precursor solution is mixed with the ferromagnetic particles to obtain a PDMS / ferromagnetic particle mixture.

[0240] The steps of preparing the microneedle patch 210 specifically include: spraying a release agent on the surface of the microneedle patch mold, standing for 5 min, and adding the PDMS / ferromagnetic particle mixture to the microneedle patch mold. A neodymium iron boron is placed below the mold. After the mixture fills the small structure of the mold under the action of the magnetic field force, it is crosslinked at 150°C for 2 h. After cooling and demolding, a microneedle patch 210 is obtained.

[0241] The steps of preparing the aggregation layer 220 specifically include: spraying a release agent on the surface of the aggregation layer mold, standing for 5 min, and adding the PDMS precursor to the aggregation layer mold. After standing for 10 min, the bubbles disappear, and then the mold is placed in an oven at 90°C for 2 h for curing. After demolding, an aggregation layer 220 is obtained.

[0242] At this point, the microchannel layer 200 is prepared.

[0243] S3, preparation of the detection electrode 300

[0244] The steps of obtaining the electrode deposition layer 310 specifically include:

[0245] 0.01 g of GO powder was uniformly dissolved in 2 g of dimethylacetamide solvent by ultrasonic-assisted technology, then 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 personalized patterned nanofiber membrane on a silicon wafer by electrostatic direct writing technology; the electrostatic 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.

[0246] The step of preparing the signal transmission wire 320 specifically comprises:

[0247] The copper paperboard is selected as the transfer substrate, and a liquid metal is coated on the surface of the substrate; and the coated substrate is subjected to drying treatment. 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, and the liquid metal is allowed to penetrate into the electrode deposition layer 310 to obtain the signal transmission wire 320.

[0248] It should be noted that, since the electrode deposition layer has a wetting property to the liquid metal, the liquid metal penetrates into the pores of the electrode deposition layer, and the sensing electrode 330 does not have a wetting property to the 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.

[0249] The step of preparing the sensing electrode 330 on the electrode deposition layer 310 specifically comprises:

[0250] The Ag / AgCl ink is printed on the electrode deposition layer 310 by combining the mask screen printing process to prepare the reference electrode, and the conductive carbon paste is printed to prepare the counter electrode and the working electrode. 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 which has been cleaned and subjected to plasma treatment, and is modified by spin coating (spun at 9000 rpm for 40 s) or drop coating. After spin coating or drop coating, the electrode is placed on a constant temperature hot table at 160°C for annealing for 15 min to form a uniform film.

[0251] The step of preparing the volatile layer 400 specifically comprises:

[0252] 10 g of PAN particles are dissolved in 85 g of DMF solvent, and 5 g of inorganic filler particles are added, and the mixture is magnetically stirred for 2 h to obtain a PAN precursor. The PAN precursor is used for planar electrospinning on the aggregation layer 220 at room temperature, and the electrospinning voltage is 20 kV, the liquid supply rate is 300 μL / h, and the spinning distance is 15 cm. Then, the voltage is reduced by 3 kV every 15 min, so that a multi-scale fiber membrane with gradually increasing fiber diameter from bottom to top is obtained, that is, the volatile layer 400 is prepared.

[0253] S5, assembly of flexible substrate 100, microchannel layer 200, detection electrode 300, and volatile layer 400

[0254] As shown in the vertical distribution, the PDMS precursor solution obtained in step S1 is used as an adhesive to uniformly point-coat the connecting surfaces of the components, and then placed in a drying oven at 90°C for 2h until completely cured to obtain a sweat in-situ detection sensor. Figure 1

[0255] 3. Performance experiment

[0256] (1) Sensor cyclic voltammetry test

[0257] The sweat in-situ sensor prepared is used to perform cyclic voltammetry test on solutions with different glucose concentrations, and the peak current is taken for result fitting.

[0258] The results are the same as those of Example 1, which proves that the peak current of the sweat in-situ detection sensor prepared by using different steps to prepare the microchannel layer can also better reflect the glucose concentration, achieving the effect of sweat detection.

[0259] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above specific embodiments, which are only illustrative but not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the scope protected by the claims.​

Claims

1. A microneedle patch-based in-situ sweat detection sensor, characterized in that, The application relates to a flexible substrate (100) comprising: a hydrophobic layer (110) for contacting the skin; a hydrophilic layer (120) disposed on the hydrophobic layer (110), the hydrophilic layer (120) having a smaller contact angle with sweat than the hydrophobic layer (110); a microchannel layer (200) comprising: a microneedle patch (210) disposed on a side of the hydrophilic layer (120) facing away from the hydrophobic layer (110); the microneedle patch (210) comprising: a patch body (211); a plurality of openings (212) disposed in the patch body (211); a plurality of tapered structures (213) respectively located in each of the openings (212), the tapered structures (213) having a channel between the tapered structures (213) and the inner wall of the opening (212), the tapered structures (213) protruding towards the hydrophilic layer (120) and being in contact with the hydrophilic layer (120); a connecting structure (214) located in the opening (212) and connected to the tapered structure (213) and the patch body (211) respectively; an aggregation layer (220) disposed on a side of the microneedle patch (210) facing away from the hydrophilic layer (120); a detection electrode (300) disposed between the aggregation layer (220) and the microneedle patch (210); a volatile layer (400) disposed on a side of the aggregation layer (220) facing away from the microneedle patch (210); the tapered structure (213) comprises any axial longitudinal section containing or parallel to a 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 tapered structure (213) comprises 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 major axis end point to the minor axis end point, and the curvature of any point on the outer contour line of the radial cross section gradually decreases from the major axis end point to the minor axis end point; the opening (212) has a circular truncated cone structure, and the diameter of the circular cross section on the side close to the hydrophilic layer (120) is greater than the diameter of the circular cross section on the side close to the aggregation layer (220); the corresponding top angle of the tapered structure (213) at the minor axis end point of the radial cross section is 3-15 degrees; the major-to-minor axis ratio of the radial cross section is 1.5-2.5:

1. the connecting structure (214) is two, and is oppositely disposed in the region between the inner wall of the opening (212) and the corresponding end point of the major axis of the radial cross section.

2. The sweat in situ detection sensor according to claim 1, characterized in that, the aggregation layer (220) comprises:

3. The sweat, in situ, detecting sensor of claim 1, wherein, a concave tapered pipe (221) disposed on the side of the aggregation layer (220) close to the microneedle patch (210) and aligned with the array of the tapered structures (213). ​ An accommodation groove (222) is arranged on the same side of the gathering layer (220) as the concave conical pipeline (221) and is used for accommodating the detection electrode (300).

4. The sweat in-situ detection sensor according to claim 3, characterized in that, The radius of the semicircular cross section of the concave conical pipeline (221) gradually decreases from the end far away from the accommodation groove (222) to the end close to the accommodation groove.

5. 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).

6. A method for producing the sweat in-situ detecting sensor according to any one of claims 1 to 5, characterized by, The preparation method comprises the following steps: The preparation steps of the flexible substrate (100) comprise: A uniform nanofiber film is deposited on a silicon wafer to obtain a hydrophobic layer (110); A uniform nanofiber film is deposited on the hydrophobic layer (110), and a hydrophilic polymer is coated on the surface of the nanofiber film to obtain a hydrophilic layer (120); The preparation steps of the microchannel layer (200) comprise: A microneedle patch model is designed, a microneedle patch mold is prepared according to the microneedle patch model, a base material is poured into the microneedle patch mold, and a microneedle patch (210) is obtained; A gathering layer model is designed, a gathering layer mold is prepared according to the gathering layer model, a base material is poured into the gathering layer mold, and a gathering layer (220) is obtained; The preparation steps of the detection electrode (300) comprise: A uniform nanofiber film is deposited on a silicon wafer to obtain an electrode deposition layer (310); A signal transmission wire (320) and a sensing electrode (330) are prepared on the electrode deposition layer (310); The preparation steps of the volatile layer (400) comprise: A nanofiber film is deposited on the gathering layer (220), and a hydrophilic polymer is coated on the side of the nanofiber film far away from the gathering 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.

7. The preparation method according to claim 6, characterized in that, The preparation method specifically comprises: A uniform TPU nanofiber film is prepared on a silicon wafer by an electrospinning process to obtain a hydrophobic layer (110); A uniform PAN nanofiber film 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 film to obtain a hydrophilic layer (120); A microneedle patch model is obtained, a microneedle patch mold is prepared according to the microneedle patch model, then pre-prepared polydimethylsiloxane (PDMS) is poured into the microneedle patch mold, and a microneedle patch (210) is obtained after curing and demolding; A gathering layer model is obtained, a gathering layer mold is prepared according to the gathering layer model, then pre-prepared polydimethylsiloxane (PDMS) is poured into the gathering layer mold, and a gathering layer (220) is obtained after curing and demolding; The thermoplastic graphene oxide / TPU composite nanofiber membrane is prepared on a silicon wafer through an electrostatic direct writing process to obtain an electrode deposition layer (310); A patterned liquid metal is formed on the electrode deposition layer (310) through a transfer printing process to obtain a signal transmission wire (320); A sensing electrode (330) is prepared on the electrode deposition layer (310) through a screen printing process, and the sensing electrode (330) comprises a working electrode, a counter electrode and a reference electrode; A uniform PAN nanofiber membrane is prepared on the surface of the aggregation layer (220) through an electrospinning process, and a hydrophilic polymer is coated on the side of the PAN nanofiber membrane away from the aggregation layer (220) to obtain a volatile layer (400); The TPU nanofiber membrane, the PAN nanofiber membrane and the thermoplastic graphene oxide / TPU composite nanofiber membrane can all be controlled in fiber diameter and porosity by adjusting electrospinning electric field intensity, nozzle distance, solution supply flow rate and fiber packing density parameters.

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