Micro-fluidic chip, sensing electrode and sensor of wearable device

Abstract

The invention discloses a micro-fluidic chip, a sensing electrode and a sensor of wearable equipment, belongs to the technical field of electrochemical method testing, and solves the technical problem that an existing wearable sensor cannot improve the sensitivity and accuracy of sweat component detection. The micro-fluidic chip comprises a substrate layer, a channel layer and a chip cover layer which are attached in sequence, the substrate layer comprises a sweat inlet and a cavity, the channel layer comprises a sweat absorbing opening, a micro-channel, a detection area, a capillary pump, a stop valve and a ventilation opening which are communicated in sequence, the sweat inlet is communicated with the sweat absorbing opening, and the cavity is communicated with the detection area. The sensing electrode is of a four-layer structure, and a working electrode located on a working electrode layer is manufactured through a chemical process. In a sensor of the wearable equipment, a sensing electrode is embedded in a cavity of a micro-fluidic chip and is used for being in contact with sweat flowing into the cavity, so that the content of glucose, sodium ions and cortisol in the sweat is detected. The method is suitable for the technical field of wearable sweat detection and can be applied to research and development of wearable detection equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical method testing, and in particular relates to the detection and preparation of sensor electrodes for wearable devices. Background Art

[0002] At present, cardiovascular diseases such as coronary heart disease, myocardial infarction, angina pectoris, and heart failure are one of the leading causes of death worldwide. In particular, more than 15 million people over the age of 60 die from cardiovascular diseases each year, which has attracted great attention in the healthcare professional field. Traditional hospital cardiovascular diagnosis, such as blood biochemical tests, blood pressure monitoring, and electrocardiograms, often cannot provide timely and affordable diagnosis. In recent years, wearable sweat sensing technology has been introduced into many research works and has made rapid progress. Among them, portable sensors for cardiovascular health monitoring have received widespread attention. However, there are still some shortcomings in the current wearable sweat detection sensors for detecting the concentration of cardiovascular disease markers. First, the sensitivity and accuracy of the sensor still need to be further improved to ensure that trace amounts of glucose, sodium ions, and cortisol in sweat can be accurately and quickly detected; secondly, the stability and durability of the sensor is also a challenge, especially when worn for a long time and used multiple times, the performance of the sensor may change. In addition, the accuracy and real-time nature of the data are also a problem. It is necessary to ensure that the data collected by the sensor can accurately reflect the concentration changes of uric acid in sweat and can be transmitted and analyzed in a timely manner. Therefore, although wearable sweat detection sensors have potential in detecting the concentration of cardiovascular disease markers in sweat, further research and improvement are still needed to improve the practical performance of the sensors and expand their application range.

[0003] In summary, the existing wearable sweat sensing technology is difficult to accurately detect the concentration of cardiovascular disease markers due to insufficient sensitivity, accuracy, stability and data real-time performance, which affects its practicality in cardiovascular health monitoring. Summary of the invention

[0004] In view of this, the present invention aims to propose a microfluidic chip, a sensing electrode and a sensor for a wearable device to solve the technical problem in the prior art that wearable sensors cannot improve the sensitivity and accuracy of detecting sweat components.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a microfluidic chip for a wearable device, wherein the microfluidic chip comprises a base layer, a channel layer and a chip cover layer which are bonded in sequence;

[0007] The base layer comprises a sweat inlet and a cavity; the sweat inlet is a through hole; the cavity is a groove, and one side of the cavity is provided with an opening at the edge of the base layer;

[0008] The channel layer includes a sweat absorption port, a microchannel, a detection area, a capillary pump, a stop valve and a vent which are connected in sequence; wherein,

[0009] The sweat absorption port is a through hole, and the sweat absorption port is connected to the sweat inlet;

[0010] The microchannel is a groove;

[0011] The detection area is a through hole, which is connected with the cavity;

[0012] The capillary pump structure includes a plurality of capillary grooves;

[0013] The vent is composed of a plurality of grooves; the plurality of grooves extend to the edge of the channel layer to communicate with the outside.

[0014] Furthermore, the sweat absorption port is coaxial with the sweat inlet, and the inner diameters of the two are the same; the aperture of the through hole is not less than 2.5 mm and not more than 3.5 mm.

[0015] Furthermore, the inner diameter of the detection area is 1.5 to 2.5 times the inner diameter of the sweat absorption port.

[0016] Furthermore, the multiple grooves of the vent are evenly distributed in parallel; the number of the multiple grooves is greater than the number of capillaries in the capillary pump; the width of each groove is not less than 0.4 mm and not more than 0.8 mm, and the spacing between adjacent grooves is not less than 0.1 mm and not more than 0.3 mm.

[0017] Furthermore, the cavity area covers the detection area.

[0018] The present invention also proposes a sensing electrode of a wearable device, wherein the sensing electrode has a four-layer structure, and the four-layer structure is sequentially: a wire layer, a reference electrode layer, a counter electrode and working electrode layer, and an insulating layer from bottom to top; the reference electrode layer covers the wire layer; the counter electrode and working electrode layer covers the reference electrode; the insulating layer covers the wire layer, the reference electrode layer, and the counter electrode and working electrode layer;

[0019] The sensing electrode comprises an electrochemical sensing electrode and a wire; the wire is fixed on a wire layer, the electrochemical sensing electrode comprises a reference electrode, a counter electrode and a working electrode, and correspondingly, the reference electrode is fixed on a reference electrode layer, and the counter electrode and the working electrode are fixed on the counter electrode and working electrode layer; the electrochemical sensing electrode is connected to an external electrical signal through the wire; the electrochemical sensing electrode is used to detect glucose, sodium ions and cortisol.

[0020] Furthermore, the reference electrode is a dot electrode point and a short arc electrode point; the counter electrode is an arc electrode point; the working electrodes are all dot electrode points; the working electrodes include three electrode units; the wires have six wires, and each wire has a terminal at the end; the reference electrode is connected to two terminals respectively through two wires, and the wires transmit reference potential signals; the three working electrodes are connected to the other three terminals respectively through three wires, and the wires transmit electrical signals detected by the three working electrodes; the counter electrode is connected to the remaining terminal through a wire, and the wire transmits a current loop signal.

[0021] Furthermore, the three electrode units of the working electrode are prepared by the following process:

[0022] The first electrode unit is used to detect glucose. The preparation method of the electrode unit is as follows: a carbon nanotube CNT dispersion and a MXene nanosheet colloidal solution are mixed in a volume ratio of 1:1, wherein the carbon nanotube dispersion is 2 mg / mL deionized water, and the concentration of the MXene nanosheet colloidal solution is 4 mg / mL; ultrasonic treatment is performed for 5 minutes; then, the carbon nanotube CNT and MXene nanosheet colloidal mixed solution is dripped onto the surface of the working electrode to completely dry it, and the volume of the mixed solution is 2 μL; a glucose oxidase solution is coated on the composite surface, and the volume of the solution is 2 μL, the concentration of the solution is 10 mg / mL, and the concentration of acetic acid in the solution is 2 wt%; glutaraldehyde is added to the surface for modification, and the volume of the glutaraldehyde is 0.5 μL and the concentration is 5%;

[0023] The second electrode unit is used to detect sodium ions. The preparation method of the electrode unit is as follows: Na ion carrier X is mixed with Na-TFPB, polyvinyl chloride and di-2-ethylethoxy sodium sebacate, and dissolved in tetrahydrofuran to obtain a mixed solution, wherein the mass of the Na ion carrier X is 10 mg, the mass of the Na-TFPB is 5.5 mg, the mass of the polyvinyl chloride is 33 mg, the mass of the di-2-ethylethoxy sodium sebacate is 654.5 mg, and the volume of the tetrahydrofuran is 6.6 mL; the mixed solution is dripped onto the surface of the working electrode with a pipette, and the volume of the mixed solution is 2 μL; after drying at room temperature for 12 hours, an ion selective membrane is formed; polyvinyl chloride and NaCl are dissolved in methanol to obtain a mixture, and the mixture is added to the reference electrode, the volume of the mixture is 4 μL, the mass of the polyvinyl chloride is 78 mg, the mass of the dissolved NaCl is 50 mg, and the volume of the methanol is 1 mL; after the film is formed, the coating is repeated once; the chloride ion retention membrane minimizes the potential drift of the reference electrode;

[0024] The third electrode unit is used to detect cortisol. The preparation method of the electrode unit is as follows: in a PBS solution containing cortisol, K3Fe(CN)6, HCl, pyrrole and FeCl3, a polypyrrole film is deposited on the surface of the working electrode by the ISTEP method to prepare a molecular imprinting polymer MIP electrode, wherein the concentration of the cortisol is 6 mmol / L, the concentration of the K3Fe(CN)6 is 5 mmol / L, the concentration of the HCl is 0.1 mol / L, the concentration of the pyrrole is 0.1 mol / L, and the concentration of the FeCl3 is 5 mmol / L; the ISTEP starting current density is set to 2 A / cm2, and the polymerization time is 600 s; after polymerization, the electrode surface is rinsed twice with deionized water and dried with nitrogen; H2O2 is added to the PBS buffer to prepare an eluent; using the CV method, the polymer electrode is over-oxidized for 20 cycles to extract the embedded cortisol molecules from the polypyrrole matrix to form a complementary cavity MIP.

[0025] The present invention also proposes a wearable sweat detection sensor, the sensor comprising a microfluidic chip, a sensing electrode and a detection circuit, the microfluidic chip is the microfluidic chip described in the present invention, and the sensing electrode is the sensing electrode described in the present invention;

[0026] The sensing electrode is embedded in the cavity of the microfluidic chip, and the wire of the sensing electrode is located at the opening of the cavity; the working electrode of the sensing electrode is exposed in the detection area;

[0027] The detection circuit includes a signal processing module and a transmission module; the sensor signal collection end of the signal processing module is connected to the wire of the sensing electrode; the collection result signal of the signal processing module is sent to the transmission module.

[0028] Furthermore, the signal processing module includes a sensor signal acquisition terminal, an amplifier, an ADC analog-to-digital converter, a UART asynchronous receiver and a STM32 processor;

[0029] The sensor signal acquisition end is connected to the wire of the sensor electrode, and the sensor signal acquisition end outputs the acquisition signal to the amplifier; the amplifier performs filtering and gain amplification on the acquisition signal and then sends it to the ADC analog-to-digital converter; the ADC analog-to-digital converter sends the digital signal to the UART asynchronous receiver and transmitter through analog-to-digital conversion; the UART asynchronous receiver and transmitter transmits the digital signal to the STM32 processor through serial communication; the STM32 processor processes the digital signal to obtain the concentration data of glucose, sodium ions and cortisol, and uses the concentration data as the acquisition result signal.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The microfluidic chip realizes real-time and continuous detection of sweat concentration through the structural design including the base layer, channel layer and chip cover layer, and can be used for monitoring cardiovascular diseases. The microfluidic chip is mainly composed of a sweat absorption port, a microchannel, a detection area, a stop valve, a capillary pump, a vent and other structures; among them, the corresponding connection between the sweat absorption port and the sweat inlet, and the transportation of the microchannel, enable the sweat components glucose, sodium ions and cortisol to be quickly transported to the detection area, significantly accelerating the speed of sweat transportation; the design of the sweat absorption port and the capillary pump ensures the stability of sweat in the detection area, and the design of the microchannel and the capillary pump enables the sweat to be quickly discharged through the microchannel after detection in the detection area, avoiding the influence of sweat accumulation on the accuracy of the test. Overall, the structural design of the microfluidic chip is based on the characteristics of small volume and dynamic update of sweat samples, and achieves the technical effect of maintaining the accuracy of the results under continuous monitoring conditions.

[0032] (2) The sensing electrode of a wearable device of the present invention can realize accurate detection of multiple sweat components. The sensing electrode includes an electrochemical sensing electrode, and the detection technology and materials used in the electrochemical sensing electrode ensure the sensitivity of the detection. For example, the glucose sensing electrode combines carbon nanotubes and glucose oxidase, and realizes high-sensitivity detection of low-concentration glucose through a specific modification method; the sodium ion selective membrane adopts an ion permeability design and can specifically detect sodium ions; the cortisol sensing electrode is based on molecular imprinting polymer (MIP) technology, and realizes high-precision identification of cortisol by targeted deposition of cortisol molecules; overall, the wearable sweat sensing technology is significantly improved in terms of sensitivity, accuracy and data real-time performance, providing an efficient and reliable solution for cardiovascular health monitoring.

[0033] (3) A wearable sweat detection sensor of the present invention, in which the sensing electrode and the microfluidic chip work together, processes and transmits signals through the detection circuit, thereby realizing real-time monitoring of the concentration change data of multiple sweat components including glucose, sodium ions, and cortisol; the sensing electrode placed on the microfluidic chip is connected to the STM32 through the front-end AD sampling circuit, and then the Bluetooth module is connected to the 32 single-chip microcomputer to realize data transmission; wherein, the front-end AD sampling circuit is responsible for converting the analog electrical signal generated by the electrochemical sensor electrode into a digital signal for further data processing; the STM32 microcontroller processes these digital signals in real time to ensure the accuracy and stability of the signal; the Bluetooth module ensures the delay-free synchronization of the data through wireless connection, and displays the dynamic change trend of the concentration of the three components of sweat in an intuitive form on the mobile terminal.

[0034] The wearable sweat detection sensor described in the present invention, through efficient data transmission and analysis, not only ensures the accuracy and stability of the output signal, but also improves the integration of the wearable sweat detection device. It is suitable for realizing real-time sweat component detection for patients with cardiovascular diseases, and provides a dynamic data basis for the analysis of the health status of patients. It can even achieve early disease warning. It has good promotion and development prospects in the application field of wearable devices.

[0035] The microfluidic chip of the wearable device described in the present invention is applicable to various existing wearable devices for collecting sweat discharged from the wearer's skin surface, and is used to achieve rapid collection and discharge of sweat.

[0036] The sensing electrode of the wearable device described in the present invention is suitable for various sensors for detecting sweat components. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 Schematic diagram of the structure of the microfluidic chip in the first embodiment; in the figure, 6 is a base layer, 7 is a sweat absorption port, 8 is a cavity, 9 is a microchannel, 10 is a capillary pump, 11 is a vent, 12 is a chip cover layer, 13 is a stop valve, 14 is a channel layer, 15 is a sweat absorption port, and 16 is a detection area;

[0039] Figure 2 Schematic diagram of the four-layer structure of the sensing electrode in the sixth specific implementation mode; in the figure, (a) is the wire layer, (b) is the counter electrode and working electrode layer, (c) is the reference electrode layer, and (d) is the insulating layer;

[0040] Figure 3 Schematic diagram of the sensing electrode structure in the sixth specific implementation mode; in the figure, 1 is a PET material substrate, 2 is a wire, 3 is a reference electrode, 4 is a working electrode, and 5 is a counter electrode;

[0041] Figure 4 is a schematic diagram of a detection circuit structure in a specific implementation mode ten;

[0042] Figure 5 This is a schematic diagram of the structure of a wearable sweat detection sensor after the microfluidic chip and the sensing electrode are combined in a ninth embodiment;

[0043] Figure 6This is a schematic diagram of the relationship between the glucose, sodium ion, cortisol concentrations and the current measurement values ​​of the electrochemical sensor module mentioned in the eleventh specific implementation mode; in the figure, the X-axis is time (Time), the unit is second (s); the Y-axis has: glucose concentration (Glu), the unit is millimole per liter (mM); sodium ion concentration (Na+), the unit is millimole per liter (mM); cortisol concentration (Cor), the unit is nanomole per liter (nM). DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0045] Specific implementation method 1, see Figure 1 This embodiment is described. A microfluidic chip for a wearable device described in this embodiment includes a base layer, a channel layer and a chip cover layer which are bonded in sequence;

[0046] The base layer comprises a sweat inlet and a cavity; the sweat inlet is a through hole; the cavity is a groove, and one side of the cavity is provided with an opening at the edge of the base layer;

[0047] The channel layer includes a sweat absorption port, a microchannel, a detection area, a capillary pump, a stop valve and a vent which are connected in sequence; wherein,

[0048] The sweat absorption port is a through hole, and the sweat absorption port is connected to the sweat inlet;

[0049] The microchannel is a groove;

[0050] The detection area is a through hole, which is connected with the cavity;

[0051] The capillary pump structure includes a plurality of capillary grooves;

[0052] The vent is composed of a plurality of grooves; the plurality of grooves extend to the edge of the channel layer to communicate with the outside.

[0053] In this embodiment, the microfluidic chip realizes real-time and continuous detection of sweat concentration through its structural design: flexible substrate layer, channel layer and chip cover layer, which is particularly suitable for monitoring cardiovascular diseases. The channel layer of the microfluidic chip is mainly composed of key structures such as sweat absorption port, microchannel, detection area, stop valve, capillary pump, and vent; among them, the corresponding connection between the sweat absorption port and the sweat inlet, and the transportation of the microchannel, enable the key components of sweat, glucose, sodium ions and cortisol, to be quickly transported to the detection area, significantly improving the speed of sweat transportation; the design of the sweat absorption port and the capillary pump ensures the stability of sweat in the detection area, and the synergistic effect of the microchannel and the capillary pump enables the sweat after detection to be quickly discharged, effectively avoiding the potential impact of sweat accumulation on the accuracy of the test. In general, the structural design of the microfluidic chip is based on the characteristics of small volume and dynamic update of sweat samples, and achieves the technical effect of maintaining the accuracy of the results under continuous monitoring conditions. .

[0054] Specific implementation method 2, this implementation method is a further limitation of the sweat absorption port and the sweat inlet in the microfluidic chip of a wearable device described in implementation method 1, the sweat absorption port and the sweat inlet are coaxial, and the inner diameters of the two are the same; the aperture of the through hole is not less than 2.5 mm and not more than 3.5 mm.

[0055] This embodiment further defines the apertures of the sweat absorption port and the sweat inlet described in the first embodiment. In this embodiment, sweat can enter from the sweat absorption port and quickly flow through the microchannel into the detection area under the action of the capillary pump. The aperture design of the sweat absorption port can accurately control the amount of sweat entering to avoid sweat waste or contamination; the sweat absorption port and the sweat inlet cooperate with the capillary pump, so that sweat can quickly flow through the microchannel without external power, reducing the complexity and energy consumption of the equipment. The through-hole design of the sweat absorption port and the sweat inlet is more suitable for wearable health monitoring equipment, which can realize non-invasive and continuous sweat collection, provide a convenient and effective solution for sweat component monitoring and analysis, and has broad application prospects in the field of physiological monitoring.

[0056] Specific implementation method three, this implementation method is a further limitation of the detection area in the microfluidic chip of a wearable device described in implementation method one; the inner diameter of the detection area is 1.5 to 2.5 times the inner diameter of the sweat absorption port.

[0057] This embodiment further defines the inner diameter of the detection area described in the first embodiment. In this embodiment, the larger inner diameter of the detection area compared to the sweat absorption port can reduce the resistance to the flow of sweat, avoid the flow rate drop or blockage caused by the narrow channel, ensure that the sweat enters the detection area smoothly, and ensure the detection efficiency; the larger inner diameter of the detection area can accommodate more sweat, increase the contact area between the glucose, sodium ions and cholesterol in the sweat and the working electrode in the electrochemical sensor electrode; because the stop valve is designed behind the detection area, the flow rate of sweat is slowed down, so that the sweat stays in the detection area for a longer time, and the overall strength and accuracy of the detection signal are improved, which is more suitable for the detection of low-concentration components such as glucose, sodium ions and cortisol in sweat.

[0058] Specific implementation mode four, this implementation mode is a further limitation of the ventilation port in the microfluidic chip of a wearable device described in implementation mode one, wherein the multiple grooves of the ventilation port are evenly distributed in parallel; the number of the multiple grooves is greater than the number of capillaries in the capillary pump (10); the width of each groove is not less than 0.4 mm and not more than 0.8 mm, and the spacing between adjacent grooves is not less than 0.1 mm and not more than 0.3 mm.

[0059] This embodiment further defines the distribution structure of the multiple grooves of the vents described in the first embodiment. In this embodiment, the air pressure balance design of the multiple vents not only allows the sweat to maintain an effective residence time in the detection area, but also allows the sweat after detection to be quickly discharged through the microchannel through the synergistic effect with the capillary pump. Due to the small volume of sweat, the vents further speed up the speed of sweat transportation, so that after the sweat passes through the microchannel and the detection area, the solid-liquid interface energy of the gradient capillary pump can be regulated to achieve autonomous transportation of trace sweat (μL level), thereby avoiding sweat accumulation and ensuring the accuracy of the test. Therefore, the design of the vents can always maintain the accuracy of the test results under continuous monitoring conditions.

[0060] Specific implementation mode 5, this implementation mode is a further limitation of the cavity in the microfluidic chip of a wearable device described in implementation mode 1, and the cavity area covers the detection area.

[0061] This embodiment further limits the area of ​​the cavity described in the first embodiment. In this embodiment, the design of the cavity area helps to maintain stable contact between sweat and the electrochemical sensing electrode, reduce signal noise caused by sweat flow or fluctuation, and improve the signal-to-noise ratio and reliability of the detection signal; the structural design of the cavity area covering the detection area enables the cavity area to accommodate a certain amount of sweat so that it evenly covers the detection area, thereby improving the contact efficiency between the electrochemical sensing electrode and the sweat components glucose, sodium ions and cortisol to enhance the detection sensitivity.

[0062] Specific implementation manner six, a sensing electrode of a wearable device described in this implementation manner, the sensing electrode has a four-layer structure, and the four-layer structure is sequentially as follows from bottom to top: a wire layer, a reference electrode layer, a counter electrode and working electrode layer, and an insulating layer; the reference electrode layer covers the wire layer; the counter electrode and working electrode layer covers the reference electrode; the insulating layer covers the wire layer, the reference electrode layer, and the counter electrode and working electrode layer;

[0063] The sensing electrode comprises an electrochemical sensing electrode and a wire (2); the wire (2) is fixed on a wire layer, the electrochemical sensing electrode comprises a reference electrode, a counter electrode and a working electrode, and correspondingly, the reference electrode is fixed on the reference electrode layer, and the counter electrode and the working electrode are fixed on the counter electrode and working electrode layers; the electrochemical sensing electrode is connected to an external electrical signal via the wire (2); the electrochemical sensing electrode is used to detect glucose, sodium ions and cortisol.

[0064] In this embodiment, see Figure 2 The four-layer structure design of the sensing electrode can be used to make a sensing patch based on autonomous sweat sampling and transmission capabilities. The sensing patch uses a three-electrode system prepared by screen printing technology to detect sweat markers. The three-electrode system includes a counter electrode, a reference electrode and a working electrode, wherein the surfaces of the three working electrodes can be modified with corresponding functional materials to achieve the detection of markers. On the whole, the four-layer structure has clear functions and a compact structure. It not only achieves high integration and reduces the volume and thickness of the sensing electrode, but also facilitates manufacturing and assembly to reduce production costs, and is more suitable for the lightweight and miniaturization requirements of wearable devices.

[0065] The electrochemical sensing electrodes are arranged on the substrate layer; the electrochemical sensing electrodes include three working electrodes for the detection of glucose, sodium ions and cortisol, two reference electrodes and one counter electrode, and the sensing electrodes include electrode point connecting wires; the counter electrode and the working electrode are carbon electrodes, and the reference electrode is a silver / silver chloride electrode, which can be prepared in batches using screen printing technology. The electrochemical sensing electrodes can simultaneously detect multiple components in sweat, including glucose, sodium ions and cortisol, to meet the diverse health monitoring needs; the reference electrode provides a stable potential reference to ensure the accuracy of the test results; the materials modified on the surface of the working electrode, such as enzymes or ion-selective membranes, achieve high sensitivity and high selectivity detection of sweat components; the synergistic effect of the counter electrode and the working electrode improves the efficiency of the electrochemical reaction and enhances the strength of the detection signal.

[0066] Specific implementation method seven, this implementation method is a further limitation of the sensing electrode of a wearable device described in implementation method six, wherein the reference electrode is a dot electrode point and a short arc electrode point; the counter electrode is an arc electrode point; the working electrodes are all dot electrode points; the working electrodes include three electrode units; the wire (2) has six wires, and each wire has a terminal at the end; the reference electrode is connected to two terminals respectively through two wires, and the wires transmit reference potential signals; the three working electrodes are connected to the other three terminals respectively through three wires, and the wires transmit electrical signals detected by the three working electrodes; the counter electrode is connected to the remaining terminal through a wire, and the wire transmits a current loop signal.

[0067] This embodiment further defines the structure of the sensing electrode of a wearable device described in Embodiment 6. In this embodiment, the design of the reference electrode, the counter electrode and the working electrode in the electrochemical sensing electrode improves the uniformity and compactness of the electrode distribution by using a hierarchical structure, which is suitable for the miniaturization requirements of wearable devices. Six wires are connected to the reference electrode, the working electrode and the counter electrode respectively. Terminals are provided at the end of each wire, and the design of the clear signal direction of the terminal optimizes the signal transmission path, reduces signal interference and energy loss, which realizes the connection between the electrode and the detection circuit, and facilitates signal transmission and wearable device integration. The reference electrode is connected to two terminals through two wires, which can provide a stable reference potential signal when the working electrode reacts; the three working electrodes are connected to the other three terminals through three wires, respectively, to realize multi-channel parallel signal transmission, and support the simultaneous detection of multiple sweat components including glucose, sodium ions and cortisol; the counter electrode is connected to the remaining terminal through a wire, which can quickly transmit the current loop signal when the working electrode reacts; the structure of the sensing electrode ensures the accuracy and reliability of the detection signal as a whole.

[0068] Specific implementation example eight, this implementation example further defines the preparation process of the three electrode units in the wearable sweat detection sensor described in implementation example six, and the three electrode units of the working electrode are prepared by the following process:

[0069] The first electrode unit is used to detect glucose. The preparation method of the electrode unit is as follows: a carbon nanotube CNT dispersion and a MXene nanosheet colloidal solution are mixed in a volume ratio of 1:1, wherein the carbon nanotube dispersion is 2 mg / mL deionized water, and the concentration of the MXene nanosheet colloidal solution is 4 mg / mL; ultrasonic treatment is performed for 5 minutes; then, the carbon nanotube CNT and MXene nanosheet colloidal mixed solution is dripped onto the surface of the working electrode to completely dry it, and the volume of the mixed solution is 2 μL; a glucose oxidase solution is coated on the composite surface, and the volume of the solution is 2 μL, the concentration of the solution is 10 mg / mL, and the concentration of acetic acid in the solution is 2 wt%; glutaraldehyde is added to the surface for modification, and the volume of the glutaraldehyde is 0.5 μL and the concentration is 5%;

[0070] The second electrode unit is used to detect sodium ions. The preparation method of the electrode unit is as follows: Na ion carrier X is mixed with Na-TFPB, polyvinyl chloride and di-2-ethylethoxy sodium sebacate, and dissolved in tetrahydrofuran to obtain a mixed solution, wherein the mass of the Na ion carrier X is 10 mg, the mass of the Na-TFPB is 5.5 mg, the mass of the polyvinyl chloride is 33 mg, the mass of the di-2-ethylethoxy sodium sebacate is 654.5 mg, and the volume of the tetrahydrofuran is 6.6 mL; the mixed solution is dripped onto the surface of the working electrode with a pipette, and the volume of the mixed solution is 2 μL; after drying at room temperature for 12 hours, an ion selective membrane is formed; polyvinyl chloride and NaCl are dissolved in methanol to obtain a mixture, and the mixture is added to the reference electrode, the volume of the mixture is 4 μL, the mass of the polyvinyl chloride is 78 mg, the mass of the dissolved NaCl is 50 mg, and the volume of the methanol is 1 mL; after the film is formed, the coating is repeated once; the chloride ion retention membrane minimizes the potential drift of the reference electrode;

[0071] The third electrode unit is used to detect cortisol. The preparation method of the electrode unit is as follows: in a PBS solution containing cortisol, K3Fe(CN)6, HCl, pyrrole and FeCl3, a polypyrrole film is deposited on the surface of the working electrode by the ISTEP method to prepare a molecular imprinting polymer MIP electrode, wherein the concentration of the cortisol is 6 mmol / L, the concentration of the K3Fe(CN)6 is 5 mmol / L, the concentration of the HCl is 0.1 mol / L, the concentration of the pyrrole is 0.1 mol / L, and the concentration of the FeCl3 is 5 mmol / L; the ISTEP starting current density is set to 2 A / cm2, and the polymerization time is 600 s; after polymerization, the electrode surface is rinsed twice with deionized water and dried with nitrogen; H2O2 is added to the PBS buffer to prepare an eluent; using the CV method, the polymer electrode is over-oxidized for 20 cycles to extract the embedded cortisol molecules from the polypyrrole matrix to form a complementary cavity MIP.

[0072] This embodiment further defines the preparation process of the three electrode units in the sensing electrode of a wearable device described in embodiment 6. In this embodiment, polydimethylsiloxane is used to prepare a microfluidic chip in conformal contact with the skin. According to research, the concentrations of markers such as glucose, sodium ions and cortisol in sweat can reflect cardiovascular health. Therefore, electrochemical methods are used for the specific detection of sweat glucose, sodium ions and cortisol. Glucose oxidase is used to selectively detect glucose, sodium ion selective membrane is used to specifically identify sodium ions, and molecular imprinting membrane is used to specifically adsorb cortisol molecules.

[0073] Preparation of glucose sensing electrode: Carbon nanotube (CNT) dispersion (2 mg / mL deionized water) and MXene nanosheet colloidal solution (4 mg / mL) were mixed in a volume ratio of 1:1 and ultrasonicated for 5 minutes. Then, 2 μL of CNT / MXene mixed solution was dropped onto the working electrode surface and allowed to dry completely, and then 2 μL of glucose oxidase solution (10 mg / mL 2wt% acetic acid) was coated on the composite surface. Finally, 0.5 μL of 5% glutaraldehyde was added to the surface for modification.

[0074] Preparation of sodium ion selective membrane: 10 mg of Na ion carrier X was mixed with 5.5 mg of Na-TFPB, 33 mg of polyvinyl chloride (PVC) and 654.5 mg of sodium di(2-ethylethoxy) sebacate, and then dissolved in 6.6 mL of tetrahydrofuran (THF). 2 μL of the solution was dropped onto the surface of the working electrode with a pipette and dried at room temperature for 12 hours to form an ion selective membrane.

[0075] Preparation of cortisol sensing electrode: In a PBS solution containing cortisol (6mmol / L), K3Fe(CN)6 (5mmol / L), HCl (0.1mol / L), pyrrole (0.1mol / L) and FeCl3 (5mmol / L), a polypyrrole film was deposited on the surface of the working electrode by the ISTEP method to prepare a molecularly imprinted polymer (MIP) electrode. The ISTEP starting current density was set to 2A / cm2 and the polymerization time was 600s. After polymerization, the electrode surface was rinsed twice with deionized water and dried with nitrogen. The eluent was prepared by adding H2O2 to the PBS buffer. Using the CV method, the polymer electrode was over-oxidized for 20 cycles to extract the embedded cortisol molecules from the polypyrrole matrix to form a complementary cavity (MIP).

[0076] In this embodiment, the sensing electrode of the present invention integrates three detection units of glucose, sodium ions and cortisol, realizes multifunctional detection, and has the consistency of preparation process. In terms of material selection in the sensing electrode process, polydimethylsiloxane (PDMS) is used to prepare the microfluidic device, which has good flexibility and biocompatibility, can conform to the skin, improve wearing comfort and sweat collection efficiency; the glucose sensing electrode is prepared using a mixed solution of carbon nanotubes (CNT) and MXene nanosheets, which enhances the conductivity and surface area of ​​the electrode and improves the detection sensitivity; the sodium ion selective membrane uses materials such as Na ion carrier X and polyvinyl chloride (PVC) to form a uniform film layer by drop coating, and the process cost is low; the cortisol sensing electrode adopts molecular imprinting polymer (MIP) technology, and this electrochemical polymerization and elution process has strong controllability; on the whole, the sensing electrode material process can realize high sensitivity, high selectivity and high stability detection of sweat components including glucose, sodium ions and cortisol, which is suitable for the real-time monitoring needs of wearable devices.

[0077] Specific embodiment nine, a wearable sweat detection sensor described in this embodiment, the sensor includes a microfluidic chip, a sensor electrode and a detection circuit, the microfluidic chip is the microfluidic chip described in any one of specific embodiments one to five, and the sensor electrode is the sensor electrode described in any one of specific embodiments six to eight; the sensor electrode is embedded in the cavity of the microfluidic chip, and the wire of the sensor electrode is located at the opening position of the cavity; the working electrode of the sensor electrode is exposed in the detection area; the detection circuit includes a signal processing module and a transmission module; the sensor acquisition signal end of the signal processing module is connected to the wire of the sensor electrode; the acquisition result signal of the signal processing module is sent to the transmission module.

[0078] In this embodiment, the wearable sweat monitoring sensor adopts an integrated structural design and an efficient signal processing module, realizes a miniaturized sweat detection structure, can shorten the detection time, improve the overall detection efficiency of the sensor, and has structural technical advantages in terms of detection sensitivity. The working electrode of the sensor electrode is exposed in the detection area and directly contacts the sweat to ensure the accuracy of signal acquisition; the sensor is embedded in the cavity of the microfluidic chip, the wire is located at the opening of the cavity, and the terminal is located outside the opening. It has a compact structure and is more portable, which is convenient for use in scenarios such as instant detection. Moreover, the sensor structure design achieves high sensitivity, miniaturization and versatility through integration, modularization and efficient signal processing, and has significant technical advantages and application value; in particular, the sensor can monitor the changes in sweat glucose, sodium ion and cortisol concentrations over a period of time, and can be used in cardiovascular disease monitoring, scientific research and daily health care. The sensor is designed with detection circuits for data acquisition, processing and wireless transmission for remote wireless monitoring, which can collect and process the concentration change data of markers in sweat in real time, and effectively convert and transmit the data, which not only ensures the accuracy and stability of the output signal, but also improves the integration of wearable sweat detection devices, and therefore has good application prospects in the field of health monitoring.

[0079] Specific implementation method ten, see Figure 4 This embodiment is described. This embodiment is a further limitation of the signal processing module in the wearable sweat detection sensor described in Embodiment 9. The signal processing module includes a sensor signal acquisition terminal, an amplifier, an ADC analog-to-digital converter, a UART asynchronous receiver and a STM32 processor.

[0080] The sensor signal acquisition end is connected to the wire (2) of the sensor electrode, and the sensor signal acquisition end outputs the acquisition signal to the amplifier; the amplifier performs filtering and gain amplification on the acquisition signal and then sends it to the ADC analog-to-digital converter; the ADC analog-to-digital converter sends the digital signal to the UART asynchronous receiver and transmitter through analog-to-digital conversion; the UART asynchronous receiver and transmitter transmits the digital signal to the STM32 processor through serial communication; the STM32 processor processes the digital signal to obtain the concentration data of glucose, sodium ions and cortisol, and uses the concentration data as the acquisition result signal.

[0081] This embodiment further defines the signal processing mode of the signal processing module. In this embodiment, the signal processing module and the transmission module are used for the detection circuit board for sensor signal acquisition and processing, and finally the mobile device for wireless signal reception. The signal processing module and the transmission module include a front-end AD sampling circuit, STM32, a Bluetooth module and a mobile device. The sensing electrode is connected to the STM32 through the front-end AD sampling circuit, and then the Bluetooth module is connected to the 32 single-chip microcomputer to realize data transmission. Through the detection circuit, the calcium ion concentration data in the sweat is collected and processed in real time, and the data is effectively converted and transmitted, which not only ensures the accuracy and stability of the output signal, but also improves the integration of the wearable sweat detection device, so it has a good application prospect.

[0082] Specific implementation method eleven is as follows Figure 6 The scheme of the present invention is limited, wherein the experimental methods without specific operating steps are all carried out in accordance with the corresponding product instructions, and the instruments, reagents, and consumables used in the examples can all be purchased from commercial companies unless otherwise specified.

[0083] Reagents: chitosan powder (Aladdin, China), acetic acid, glucose oxidase (Macklin, China), glutaraldehyde (CH2O)2 (Macklin, China), polyethylene terephthalate (Macklin, China), carbon nanotubes (Nanjing Xianfeng Nanomaterials Co., Ltd., China), glucose, NaCl, methanol (CH3OH) (Macklin, China), polyethylene (Aladdin, China), sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (Na-TFPB) (Macklin, China), polyvinyl chloride (Aladdin, China), sodium di(2-ethylethoxy) sebacate (DOS) (Aladdin, China), tetrahydrofuran (THF) (Aladdin, China), sodium ionophore X (Macklin), Cortisol (Macklin, China), K3Fe(CN)6, FeCl3, K4Fe(CN)6, KCl (Macklin, China), Prussian blue (PB) (Aladdin, China), pyrroole (Macklin), polydimethylsiloxane (PDMS) (Macklin, China), screen printing template, dishwashing liquid (Tianlong Screen Printing, Taobao), conductive silver paste (Shanghai Ouyi Organic Optoelectronic Materials), conductive carbon ink, silver chloride conductive ink, UV curable insulating ink (Taobao, artificial sweat (Shanghai Yuanye Biotechnology Co., Ltd.), helmet anti-fog agent (Taobao, China), deionized water, hydrochloric acid, phosphate buffer (Macklin, China), Ti3AlC2 (Jilin 11 Technology, China).

[0084] 1) Preparation of wearable sweat detection sensor;

[0085] The sensor can be prepared as a flexible sensing patch; the electrode of the sensor is a flexible electrode; the preparation method of the sensor is as follows: four customized templates are used to make screen-printed electrodes: one for the conductor layer, one for the working electrode and counter electrode layer, one for the reference electrode layer, and one for the insulating layer. The detailed information of the template is as follows Figure 1 As shown. First, the conductor layer is printed on the PET surface with silver paste, and then baked in an oven at 60°C for 30 minutes. Secondly, the working electrode and the counter electrode are printed on the PET film containing the conductor layer with carbon ink, and then baked in an oven at 60°C for 30 minutes. Next, the reference electrode layer and the insulating layer are printed on the treated surface with the same procedure. Finally, the PET film is irradiated under a UV lamp until the insulating material is completely cured.

[0086] 2) Design and preparation of microfluidic chips;

[0087] The microfluidic structure was designed and simulated using ANSYS 2020R2 software and SpaceClaim Direct Modeler (SCDM) in Fluent. The designed microfluidic chip drawings were then provided to suppliers for the manufacture of microfluidic chips. The microfluidic chip mainly includes structures such as sweat absorption ports, microchannels, detection areas, stop valves, capillary pumps, and vents. Sweat can enter from the sweat absorption ports and flow quickly through the microchannels into the detection area under the action of the capillary pump. Since a stop valve is designed behind the detection area, the flow rate of sweat is slowed down, allowing the sweat to stay in the detection area longer.

[0088] 3) Preparation of sensing electrodes;

[0089] Preparation of glucose sensing electrode: Carbon nanotube (CNT) dispersion (2 mg / mL deionized water) and MXene nanosheet colloidal solution (4 mg / mL) were mixed in a volume ratio of 1:1 and ultrasonicated for 5 minutes. Then, 2 μL of CNT / MXene mixed solution was dropped onto the working electrode surface and allowed to dry completely, and then 2 μL of glucose oxidase solution (10 mg / mL 2wt% acetic acid) was coated on the composite surface. Finally, 0.5 μL of 5% glutaraldehyde was added to the surface for modification.

[0090] Preparation of sodium ion selective membrane: 10 mg of Na ion carrier X was mixed with 5.5 mg of Na-TFPB, 33 mg of polyvinyl chloride (PVC) and 654.5 mg of sodium di(2-ethylethoxy) sebacate, and then dissolved in 6.6 mL of tetrahydrofuran (THF). 2 μL of the solution was dropped onto the surface of the working electrode with a pipette and dried at room temperature for 12 hours to form an ion selective membrane.

[0091] Na + Modification of the reference electrode of the sensor: 78 mg of PVB and 50 mg of NaCl were dissolved in 1 mL of methanol. 4 μL of the mixture was added to the reference electrode. After the film was formed, the coating was repeated once more. This chloride ion retaining film minimized the potential drift of the reference electrode.

[0092] Preparation of cortisol sensing electrode: In the presence of cortisol (6mmol / L), K 3 Fe(CN) 6 (5mmol / L), HCl (0.1mol / L), pyrrole (0.1mol / L) and FeCl 3 In a PBS solution containing 5 mmol / L of 5% pyrrole, a polypyrrole film was deposited on the surface of the working electrode by the ISTEP method to prepare a molecularly imprinted polymer (MIP) electrode. The ISTEP starting current density was set to 2 A / cm 2 , the polymerization time was 600 s. After polymerization, the electrode surface was rinsed twice with deionized water and dried with nitrogen. H 2 O 2 Preparation of eluent. Using the CV method, the polymer electrode was over-oxidized for 20 cycles to extract the embedded cortisol molecules from the polypyrrole matrix to form a complementary cavity (MIP).

[0093] 4) Electrochemical signal acquisition and transmission circuit system;

[0094] The detection circuit is mounted on a flexible circuit board. The manufacturing method of the flexible circuit board is as follows: the signal acquisition and detection circuit of the sensor is designed, and the PCB diagram of the designed detection circuit is drawn using Altium Designer. The drawing is then provided to the foundry for manufacturing the flexible printed circuit (FPC).

[0095] The signal processing module and transmission module include front-end AD sampling circuit, STM32, Bluetooth module and mobile device. The sensing electrode is connected to STM32 through the front-end AD sampling circuit, and then the Bluetooth module is connected to the 32 microcontroller to realize data transmission.

[0096] 5) Electrochemical sensing electrodes of the sensing electrodes are used for glucose, sodium ion and cortisol concentration detection;

[0097] Real-time monitoring of sweat on the surface of human skin: Before the test, wipe the subject's skin with alcohol, attach the prepared wearable sweat detection sensor to the human arm, and monitor the sweat biomarkers during exercise. Through the processing of the signal processing module and the transmission module, the marker concentration obtained by the calculation method of the present invention is directly fed back to the mobile terminal. After wearing for a period of time, the mobile terminal receives real-time marker concentration information, which reflects the trend of the subject's sweat marker concentration change during this stage, such as Figure 6 As shown, the X-axis is time (Time), in seconds (s), showing the dynamic change curve of the marker over time, with the concentration gradually increasing and gradually tending to stabilize; the Y-axis includes: glucose concentration (Glu, in mM), sodium ion concentration (Na+, in mM), and cortisol concentration (Cor, in nM).

[0098] The specific embodiments of the present invention disclosed above are only used to help explain the present invention. The specific embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A microfluidic chip for a wearable device, characterized in that: The microfluidic chip comprises a base layer (6), a channel layer (14) and a chip cover layer (12) which are bonded in sequence; The base layer (6) comprises a sweat inlet (7) and a cavity (8); the sweat inlet (7) is a through hole; the cavity (8) is a groove, and one side of the cavity is provided with an opening at the edge of the base layer (6); The channel layer (14) comprises a sweat absorption port (15), a microchannel (9), a detection area (16), a capillary pump (10), a stop valve (13) and a vent (11) which are connected in sequence; wherein: The sweat absorption port (15) is a through hole, and the sweat absorption port is connected to the sweat inlet (7); The microchannel (9) is a groove; The detection area (16) is a through hole, which is connected to the cavity (8); The capillary pump structure (10) comprises a plurality of capillary grooves; The ventilation opening (11) is composed of a plurality of grooves; the plurality of grooves extend to the edge of the channel layer (14) to communicate with the outside.

2. A microfluidic chip for a wearable device according to claim 1, characterized in that: The sweat absorption port (15) is coaxial with the sweat inlet (7), and the inner diameters of the two are the same; the diameter of the through hole is not less than 2.5 mm and not more than 3.5 mm.

3. The microfluidic chip for a wearable device according to claim 1, characterized in that: The inner diameter of the detection area (16) is 1.5 to 2.5 times the inner diameter of the sweat absorption port (15).

4. The microfluidic chip for a wearable device according to claim 1, characterized in that: The plurality of grooves of the vent (11) are evenly distributed in parallel; the number of the plurality of grooves is greater than the number of capillaries in the capillary pump (10); the width of each groove is not less than 0.4 mm and not more than 0.8 mm, and the spacing between adjacent grooves is not less than 0.1 mm and not more than 0.3 mm.

5. The microfluidic chip for a wearable device according to claim 1, characterized in that: The cavity (8) area covers the detection zone (16).

6. A sensing electrode for a wearable device, characterized in that: The sensing electrode has a four-layer structure, which is sequentially: a wire layer, a reference electrode layer, a counter electrode and working electrode layer, and an insulating layer from bottom to top; the reference electrode layer covers the wire layer; the counter electrode and working electrode layer covers the reference electrode; the insulating layer covers the wire layer, the reference electrode layer, and the counter electrode and working electrode layer; The sensing electrode comprises an electrochemical sensing electrode and a wire (2); the wire (2) is fixed on a wire layer, the electrochemical sensing electrode comprises a reference electrode, a counter electrode and a working electrode, and correspondingly, the reference electrode is fixed on the reference electrode layer, and the counter electrode and the working electrode are fixed on the counter electrode and working electrode layers; the electrochemical sensing electrode is connected to an external electrical signal via the wire (2); the electrochemical sensing electrode is used to detect glucose, sodium ions and cortisol.

7. A sensor electrode for a wearable device according to claim 6, characterized in that: The reference electrode is a round electrode point and a short arc electrode point; The counter electrode is an arc-shaped electrode point; The working electrodes are all dot electrodes; the working electrodes include three electrode units; The wire (2) has six wires, and each wire has a terminal at the end; The reference electrode is connected to two terminals respectively through two wires, which transmit reference potential signals; The three working electrodes are connected to the other three terminals respectively through three wires, and the wires transmit the electrical signals detected by the three working electrodes; The counter electrode is connected to the remaining terminal via a wire that transmits a current loop signal.

8. The sensing electrode of a wearable device according to claim 6, characterized in that: The three electrode units of the working electrode are prepared by the following process: The first electrode unit is used to detect glucose. The preparation method of the electrode unit is as follows: a carbon nanotube CNT dispersion and a MXene nanosheet colloidal solution are mixed in a volume ratio of 1:1, wherein the carbon nanotube dispersion is 2 mg / mL deionized water, and the concentration of the MXene nanosheet colloidal solution is 4 mg / mL; ultrasonic treatment is performed for 5 minutes; then, the carbon nanotube CNT and MXene nanosheet colloidal mixed solution is dripped onto the surface of the working electrode to completely dry it, and the volume of the mixed solution is 2 μL; a glucose oxidase solution is coated on the composite surface, and the volume of the solution is 2 μL, the concentration of the solution is 10 mg / mL, and the concentration of acetic acid in the solution is 2 wt%; glutaraldehyde is added to the surface for modification, and the volume of the glutaraldehyde is 0.5 μL and the concentration is 5%; The second electrode unit is used to detect sodium ions. The preparation method of the electrode unit is as follows: Na ion carrier X is mixed with Na-TFPB, polyvinyl chloride and di-2-ethylethoxy sodium sebacate, and dissolved in tetrahydrofuran to obtain a mixed solution, wherein the mass of the Na ion carrier X is 10 mg, the mass of the Na-TFPB is 5.5 mg, the mass of the polyvinyl chloride is 33 mg, the mass of the di-2-ethylethoxy sodium sebacate is 654.5 mg, and the volume of the tetrahydrofuran is 6.6 mL; the mixed solution is dripped onto the surface of the working electrode with a pipette, and the volume of the mixed solution is 2 μL; and an ion selective membrane is formed after drying at room temperature for 12 hours; Polyvinyl chloride and NaCl are dissolved in methanol to obtain a mixture, and the mixture is added to a reference electrode, the volume of the mixture is 4 μL, the mass of the polyvinyl chloride is 78 mg, the mass of the dissolved NaCl is 50 mg, and the volume of the methanol is 1 mL; after the film is formed, the coating is repeated once; the chloride ion retention film minimizes the potential drift of the reference electrode; The third electrode unit is used to detect cortisol. The preparation method of the electrode unit is as follows: in a PBS solution containing cortisol, K3Fe(CN)6, HCl, pyrrole and FeCl3, a polypyrrole film is deposited on the surface of the working electrode by the ISTEP method to prepare a molecular imprinting polymer MIP electrode, wherein the concentration of the cortisol is 6 mmol / L, the concentration of the K3Fe(CN)6 is 5 mmol / L, the concentration of the HCl is 0.1 mol / L, the concentration of the pyrrole is 0.1 mol / L, and the concentration of the FeCl3 is 5 mmol / L; the ISTEP starting current density is set to 2 A / cm2, and the polymerization time is 600 s; after polymerization, the electrode surface is rinsed twice with deionized water and dried with nitrogen; H2O2 is added to the PBS buffer to prepare an eluent; using the CV method, the polymer electrode is over-oxidized for 20 cycles to extract the embedded cortisol molecules from the polypyrrole matrix to form a complementary cavity MIP.

9. A wearable sweat detection sensor, characterized in that: The sensor comprises a microfluidic chip, a sensing electrode and a detection circuit, wherein the microfluidic chip is the microfluidic chip according to any one of claims 1 to 5, and the sensing electrode is the sensing electrode according to any one of claims 6 to 8; The sensing electrode is embedded in the cavity (8) of the microfluidic chip, and the wire (2) of the sensing electrode is located at the opening of the cavity (8); the working electrode of the sensing electrode is exposed in the detection area (16); The detection circuit comprises a signal processing module and a transmission module; the sensor signal collection end of the signal processing module is connected to the wire (2) of the sensing electrode; and the collection result signal of the signal processing module is sent to the transmission module.

10. A sensor for a wearable device according to claim 9, characterized in that: The signal processing module includes a sensor signal acquisition terminal, an amplifier, an ADC analog-to-digital converter, a UART asynchronous receiver and a STM32 processor; The sensor signal acquisition end is connected to the wire (2) of the sensor electrode, and the sensor signal acquisition end outputs the acquisition signal to the amplifier; the amplifier performs filtering and gain amplification on the acquisition signal and then sends it to the ADC analog-to-digital converter; the ADC analog-to-digital converter sends the digital signal to the UART asynchronous receiver and transmitter through analog-to-digital conversion; the UART asynchronous receiver and transmitter transmits the digital signal to the STM32 processor through serial communication; the STM32 processor processes the digital signal to obtain the concentration data of glucose, sodium ions and cortisol, and uses the concentration data as the acquisition result signal.

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