Multi-mode directional perspiration sensor and preparation method thereof

Abstract

The invention discloses a multi-mode directional perspiration sensor and a preparation method thereof, and belongs to the technical field of sensors. The electrophysiological electrode, the hydrophobic layer, the hydrophilic layer and the electrochemical electrode are arranged in sequence, the control circuit is arranged on the hydrophilic layer to collect signals, during use, the electrophysiological electrode and the hydrophobic layer are attached to the skin, sweat is discharged to a contact interface of the skin and the sensor through sweat glands, and the sensor is used for detecting the sweat glands. Sweat is directionally conveyed to the upper surfaces of the electrochemical electrode and the control circuit from the contact interface of the skin and the sensor, so that on one hand, the interference of the sweat on electrophysiological signal acquisition can be reduced, and the electrophysiological signal is enhanced; on the other hand, sweat is gathered on the upper surface of the sensor, so that electrochemical signal acquisition is facilitated, and meanwhile, the sensor has relatively good air permeability and wearing comfort.

Description

Technical Field

[0001] This application relates to the field of sensor technology, specifically to a multimodal directional perspiration sensor and its fabrication method. Background Technology

[0002] Traditional wearable devices widely use rigid materials, including metal and plastic shells. While these materials have mature manufacturing processes, they lack flexibility and are prone to localized detachment or uneven pressure when in contact with the curved surfaces of the human body. High interfacial impedance leads to baseline drift and severe motion artifacts, making them unsuitable for long-term dynamic monitoring. Existing wearable devices are gradually incorporating flexible materials such as silicone elastomers, stretchable plastic films, and elastic textiles to achieve a hybrid of rigid and flexible materials. Flexible materials used in parts that come into contact with human skin, with a Young's modulus closer to that of skin, can adapt to skin deformation to some extent, thereby improving signal quality and comfort.

[0003] In addition, most current wearable sensing devices can only collect one type of physiological signal to assess the human body from a single dimension, making it difficult to comprehensively and accurately reflect the true health status of the human body.

[0004] The drawbacks of existing flexible wearable sensors include the use of non-breathable materials, which hinder the perspiration and heat transfer of the skin, easily irritating the skin or causing inflammation. Furthermore, as sweat accumulates during exercise, forming a sweat film between the skin and the device, it reduces the adhesion of the fiber membrane, leading to slippage and signal interference. Even breathable materials like textiles, due to limitations in textile manufacturing processes, have low porosity and slow sweat evaporation rates, failing to meet the high-quality, comfortable wearable requirements for sports applications. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the existing technology and provide a multimodal directional perspiration sensor and its preparation method.

[0006] To achieve the above objectives, in a first aspect of this application, a multimodal directional perspiration sensor is provided, comprising an electrophysiological electrode, a hydrophobic layer, a hydrophilic layer, an electrochemical electrode, and a control circuit, wherein the electrophysiological electrode, the hydrophobic layer, the hydrophilic layer, and the electrochemical electrode are arranged sequentially, the control circuit is disposed on the hydrophilic layer, and the electrophysiological electrode and the electrochemical electrode are respectively connected to the control circuit via wires, wherein the electrochemical electrode comprises a working electrode, a reference electrode, and an auxiliary electrode.

[0007] Preferably, the control circuit includes an electrophysiological acquisition module, an electrochemical acquisition module, a microcontroller, and a signal transmission module. The electrophysiological acquisition module and the electrochemical acquisition module are respectively connected to the microcontroller via wires, and the microcontroller is connected to the signal transmission module via wires.

[0008] More preferably, the control circuit further includes a power supply, a voltage regulation module, and a reference voltage module, wherein the power supply, the voltage regulation module, and the reference voltage module are connected in sequence by wires, and the power supply is connected to the microcontroller by wires.

[0009] Preferably, the water contact angle of the hydrophobic layer is not less than 110°, and the water contact angle of the hydrophilic layer is not greater than 60°.

[0010] Preferably, the average pore size of the hydrophobic layer is greater than the average pore size of the hydrophilic layer.

[0011] Preferably, the hydrophobic layer is formed by randomly stacked fibers, wherein the average diameter of the fibers is 2~12μm.

[0012] Preferably, the hydrophilic layer is formed by randomly stacking spindle fibers, wherein the spindle fibers have a spindle body and fibers connected to the spindle body, wherein the average major axis diameter of the spindle body is 2~10μm, and the average diameter of the fibers connected to the spindle body is 0.5~5μm.

[0013] In a second aspect, this application provides a method for fabricating a multimodal directional perspiration sensor as described in the first aspect, comprising the following steps: S1. Prepare the hydrophilic layer by electrospinning process; S2. A hydrophobic layer is prepared by electrostatic hair spinning process; S3. Patterned electrophysiological electrodes are prepared on the sacrificial layer by magnetron sputtering and laser cutting. The electrophysiological electrodes are transferred to the hydrophobic layer. The first sacrificial layer is removed by atomization dissolution, thereby completing the setting of the electrophysiological electrodes on the hydrophobic layer. S4. Transfer the auxiliary electrode, working electrode and reference electrode to the hydrophilic layer respectively, and remove the first sacrificial layer by atomization dissolution, thereby completing the setting of the electrochemical electrode on the hydrophilic layer; S5. Stack the hydrophobic layer and the hydrophilic layer, and place the hydrophobic layer and the hydrophilic layer between the electrophysiological electrode and the electrochemical electrode. Set the modules of the control circuit on the hydrophilic layer, and form wires by printing conductive ink to realize the electrical connection of each module. Waterproof encapsulate each module and wires by printing an elastic polymer coating.

[0014] Preferably, step S1 specifically includes: The first polymer and the first organic solvent are mixed to prepare spinning solution A. The resulting spinning solution A is loaded into a syringe. The needle on the syringe is used as the spinning nozzle. The syringe is installed on an electrospinning machine to form an electrospinning device. Then, the distance between the electrospinning device and the receiver is adjusted, the switch of the electrospinning device is turned on, the spinning parameters are set, and electrospinning is performed. After spinning is completed, the obtained material is cooled to obtain a hydrophilic layer. The first polymer in the spinning solution A has a mass percentage content of 5-10 wt%; the first polymer includes styrene-ethylene-butene-styrene block copolymer (SEBS).

[0015] Preferably, step S2 specifically includes: mixing the second polymer with the second organic solvent to prepare spinning solution B; loading the obtained spinning solution B into a syringe; using the needle installed on the syringe as a spinning nozzle; installing the syringe on an electrospinning apparatus to form an electrospinning device; then adjusting the distance between the electrospinning device and the receiver; turning on the switch of the electrospinning device; setting the spinning parameters; performing electrospinning; and cooling the obtained material after spinning to obtain a hydrophobic layer. In step S2, the mass percentage of the second polymer in the spinning solution B is 13~23wt%; the second polymer includes styrene-ethylene-butene-styrene block copolymer (SEBS) and polyoxyethylene polyoxypropylene ether (F127), and the mass ratio of the styrene-ethylene-butene-styrene block copolymer (SEBS) to the polyoxyethylene polyoxypropylene ether (F127) is 1:(0.6~2).

[0016] Compared with the prior art, the beneficial effects of this application are as follows: This application sequentially arranges an electrophysiological electrode, a hydrophobic layer, a hydrophilic layer, and an electrochemical electrode. A control circuit is installed on the hydrophilic layer for signal acquisition. During use, the electrophysiological electrode and the hydrophobic layer adhere to the skin. Sweat is excreted through sweat glands to the interface between the skin and the sensor. This allows the sweat to be directionally transported from the skin-sensor interface to the upper surface of the electrochemical electrode and the control circuit. This reduces interference from sweat on the electrophysiological signal acquisition, thereby enhancing the electrophysiological signal. Furthermore, the accumulation of sweat on the upper surface of the sensor facilitates electrochemical signal acquisition and also provides the sensor with good breathability and wearing comfort. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the multimodal directional perspiration sensor provided in this application; Figure 2 A schematic diagram of the control circuit provided in this application; Figure 3 An integrated photograph of the electrophysiological electrodes and the hydrophilic layer; Figure 4 This is a scanning electron microscope image of the hydrophilic layer; Figure 5 This is a scanning electron microscope image of the hydrophobic layer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0020] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0021] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] Please see Figures 1-3 As shown, in a first aspect of this application, this application provides a multimodal directional perspiration sensor, including an electrophysiological electrode 1, a hydrophobic layer 2, a hydrophilic layer 3, an electrochemical electrode 4, and a control circuit 5. The electrophysiological electrode 1, the hydrophobic layer 2, the hydrophilic layer 3, and the electrochemical electrode 4 are arranged sequentially. The control circuit 5 is disposed on the hydrophilic layer 3. The electrophysiological electrode 1 and the electrochemical electrode 4 are respectively connected to the control circuit 5 through wires 6. The electrochemical electrode 4 includes a working electrode, a reference electrode, and an auxiliary electrode.

[0023] This application sequentially arranges an electrophysiological electrode 1, a hydrophobic layer 2, a hydrophilic layer 3, and an electrochemical electrode 4. Signal acquisition is performed by a control circuit 5 set on the hydrophilic layer 3. In use, the electrophysiological electrode 1 and the hydrophobic layer 2 are in contact with the skin. Sweat is discharged through sweat glands to the contact interface between the skin and the sensor, allowing the sweat to be directionally transported from the skin-sensor contact interface to the upper surface of the electrochemical electrode 4 and the control circuit 5. On the one hand, this reduces the interference of sweat on the acquisition of electrophysiological signals, thereby enhancing the electrophysiological signals; on the other hand, the accumulation of sweat on the upper surface of the sensor facilitates the acquisition of electrochemical signals, while also giving the sensor good breathability and wearing comfort.

[0024] The multimodal directional perspiration sensor described in this application collects differential current from the body surface through electrophysiological electrodes 1 and measures real-time electrocardiogram (ECG) signals. In this application, the electrophysiological electrodes 1 are placed on a hydrophobic layer 2. During use, sweat can form a uniform conductive layer between the electrophysiological electrodes 1 and the skin, filling the micro-gaps between the electrodes and the skin, improving the interfacial contact impedance, and enhancing the conductivity of the electrodes. At the same time, the substrate composed of the hydrophobic layer 2 and the hydrophilic layer 3 guides the sweat to the sensor surface, avoiding the accumulation of a large amount of sweat at the interface between the electrophysiological electrodes 1 and the skin, which could cause electrode displacement and poor contact, thereby improving the accuracy of electrophysiological signal acquisition. The hydrophobic layer 2 and the hydrophilic layer 3 directionally guide sweat from the sensor-skin interface, causing the sweat to accumulate at the electrochemical electrode 4. This facilitates the acquisition of current or voltage signals through the electrochemical electrode 4, enabling real-time measurement of the concentrations of various biomarkers in the sweat. The electrochemical sensor, composed of the electrochemical electrode 4 and the control circuit 5, exhibits excellent sensitivity, capable of sensitively detecting glucose, lactic acid, and H+. + Na + K + While detecting key biomarkers, it can effectively resist interference from other sweat components and has excellent selectivity. This allows for accurate detection of the dynamic changes in the concentration of various biomarkers in sweat produced during human exercise, reflecting the physiological state of the human body from multiple perspectives. The mean absolute error and mean absolute percentage error of the obtained data are both at low levels, demonstrating high measurement accuracy.

[0025] This application enables physical-chemical multimodal monitoring, and the sensors provided in this application can provide a more comprehensive and accurate assessment of human health status.

[0026] In some embodiments, the control circuit 5 includes an electrophysiological acquisition module 51, an electrochemical acquisition module 52, a microcontroller 53, a signal transmission module 54, a power supply 55, a voltage regulation module 56, and a reference voltage module 57. The electrophysiological acquisition module 51 and the electrochemical acquisition module 52 are respectively connected to the microcontroller 53 via wires. The microcontroller 53 is connected to the signal transmission module 54 via wires. The power supply 55, the voltage regulation module 56, and the reference voltage module 57 are connected sequentially via wires. The power supply 55 is connected to the microcontroller 53 via wires.

[0027] The signal transmission module 54 is a Bluetooth antenna, and the microcontroller 53 is connected to a host computer (such as a mobile phone). The host computer can be a mobile phone or a tablet computer.

[0028] The electrophysiological acquisition module 51 includes a low-noise amplifier and an ADC analog-to-digital converter. The electrophysiological electrode 4, the low-noise amplifier, and the ADC are connected in sequence by wires.

[0029] In some embodiments, the control circuit 52 further includes an encapsulation layer 58, and the electrophysiological acquisition module 51, the electrochemical acquisition module 52, the microcontroller 53, the signal transmission module 54, the power supply 55, the voltage regulation module 56, and the reference voltage module 57 are located in the space formed by the encapsulation layer 58 and the hydrophilic layer 3.

[0030] In some embodiments, the difference between the water contact angle of the hydrophobic layer 2 and the water contact angle of the hydrophilic layer 3 is 70 to 115°. For example, the difference between the water contact angle of the hydrophobic layer 2 and the water contact angle of the hydrophilic layer 3 can be 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115° or any two of these values.

[0031] In some embodiments, the water contact angle of the hydrophobic layer 2 is not less than 110°, and the water contact angle of the hydrophilic layer 3 is not greater than 60°.

[0032] For example, the water contact angle of the hydrophobic layer 2 can be 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, 150° or any two of these values; the water contact angle of the hydrophilic layer 3 can be 30°, 35°, 40°, 45°, 50°, 55°, 60° or any two of these values.

[0033] In some embodiments, the average pore size of the hydrophobic layer 2 is greater than the average pore size of the hydrophilic layer 3.

[0034] In some embodiments, the ratio between the average pore size of the hydrophobic layer 2 and the average pore size of the hydrophilic layer 3 is 1.1 to 3.

[0035] For example, the ratio between the average pore size of the hydrophobic layer 2 and the average pore size of the hydrophilic layer 3 is 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 or any range of two sets of average pore size ratios.

[0036] In some embodiments, the average pore size of the hydrophobic layer 2 is 10~40μm, and the average pore size of the hydrophilic layer 3 is 5~20μm.

[0037] For example, the average pore size of the hydrophobic layer 2 can be 10μm, 12.5μm, 15μm, 17μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm or any two of these values, and the average pore size of the hydrophilic layer 3 can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 20μm or any two of these values.

[0038] In some embodiments, the hydrophobic layer 2 is formed by randomly stacked fibers, wherein the average diameter of the fibers is 2~12μm.

[0039] For example, the average diameter of the fibers in the hydrophobic layer 2 is 2μm, 2.3μm, 3μm, 4μm, 5μm, 6μm, 6.1μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm or any two of these values.

[0040] In some embodiments, the hydrophilic layer 3 is formed by randomly stacked spindle fibers, wherein the spindle fibers have spindle bodies and fibers connected to the spindle bodies, wherein the average major axis diameter of the spindle bodies is 2~10μm, the average diameter of the fibers in the spindle fibers is 0.5~5μm, and the distribution density of the spindle bodies on the surface of the hydrophilic layer is 300~1500 / mm. 2 .

[0041] For example, the average major axis diameter of the spindle can be 2μm, 3μm, 4μm, 4.3μm, 4.6μm, 5μm, 5.5μm, 6μm, 6.7μm, 7μm, 8μm, 9μm, 10μm, or any two sets of values ​​therein, and the average diameter of the fibers in the spindle fiber can be 0.5μm, 1μm, 1.2μm, 2μm, 3μm, 4μm, 5μm, or any two sets of values ​​therein. The distribution density of the spindles in the hydrophilic layer 3 can be 300 / mm². 2 400 pieces / mm 2 500 pieces / mm 2 600 pieces / mm 2 700 pieces / mm 2 740 pieces / mm 2 750 pieces / mm 2 800 pieces / mm 2 900 pieces / mm 2 980 pieces / mm 2 1000 pieces / mm 2 1100 pieces / mm 2 1200 pieces / mm 2 1300 pieces / mm 2 1350 pieces / mm 2 1400 pieces / mm 2 1440 pieces / mm 2 1500 pieces / mm 2 Or a range consisting of any two sets of values.

[0042] In this application, the hydrophobic layer 2 has a larger pore size and thicker, more uniformly sized fibers, which can directionally transport sweat from the hydrophobic layer 2 to the hydrophilic layer 3, enabling longitudinal sweat expulsion. At the same time, it can promote the lateral movement of sweat in the hydrophilic layer 3, allowing sweat to flow quickly from the fabric edge and preventing sweat from accumulating between the sensor and the skin. Compared with the hydrophobic layer 2, the hydrophilic layer 3 in this application has a smaller pore size, finer fibers, and a periodic spindle structure. Due to the presence of the spindle structure, the fiber curvature in the hydrophilic layer 3 is greater, thereby forming a microstructure gradient in the substrate composed of the hydrophilic layer 3 and the hydrophobic layer 2, allowing liquid to spontaneously transport from the hydrophobic layer 2 to the hydrophilic layer 3.

[0043] The inventors discovered through research that by constructing a hydrophilic gradient and a microstructure gradient through a hydrophilic layer 3 and a hydrophobic layer 2, under the combined action of the hydrophilic gradient, the microstructure gradient, and the specific spindle structure in the hydrophilic layer, sweat is directed from the interface between the sensor and the skin to the sensor surface, avoiding the accumulation of a large amount of sweat at the interface between the electrode and the skin, which would cause electrode displacement and poor contact, thereby improving the quality of electrophysiological signal acquisition.

[0044] This application achieves sweat management for wearable sensors by designing and fabricating structured directional sweat-wicking nanofibers, realizing moisture and heat management at the skin-sensor interface, significantly improving the wearability of the sensors, enhancing electrophysiological signals and accurately acquiring sweat electrochemical signals, and enabling a more comprehensive and accurate assessment of human health through physical-chemical multimodal monitoring.

[0045] In a second aspect, this application provides a method for fabricating a multimodal directional perspiration sensor, comprising the following steps: S1. Hydrophilic layer 3 is prepared by electrospinning process; S2. Hydrophobic layer 2 is prepared by electrospinning process; S3. Patterned electrophysiological electrodes 1 are prepared on the sacrificial layer by magnetron sputtering and laser cutting. Electrophysiological electrodes 1 are transferred to hydrophobic layer 2. The first sacrificial layer is removed by atomization dissolution, thereby completing the setting of electrophysiological electrodes 1 on hydrophobic layer 2. S4. Patterned auxiliary electrodes are fabricated on the sacrificial layer by magnetron sputtering and laser cutting processes; Patterned electrodes were fabricated on the sacrificial layer, and oxidases were modified onto the resulting electrodes to obtain the working electrodes; Patterned electrodes were fabricated on the sacrificial layer using magnetron sputtering and laser cutting processes. Conductive ink was then printed onto the resulting electrodes to obtain a reference electrode. The auxiliary electrode, working electrode and reference electrode are transferred to the hydrophilic layer 3 respectively, and the first sacrificial layer is removed by atomization dissolution, thereby completing the setting of the electrochemical electrode 4 on the hydrophilic layer 3; S5. Stack the hydrophobic layer 2 and the hydrophilic layer 3, and place the hydrophobic layer 2 and the hydrophilic layer 3 between the electrophysiological electrode 1 and the electrochemical electrode 4. Set each module of the control circuit 5 on the hydrophilic layer 3, and form wires by printing conductive ink to realize the electrical connection of each module. Waterproof encapsulate each module and wires by printing an elastic polymer coating.

[0046] The applicant discovered through research that by depositing metal on a sacrificial layer using magnetron sputtering and integrating the electrode with a hydrophilic or hydrophobic layer using sacrificial layer transfer technology, the prepared electrophysiological and electrochemical electrodes can be made ultrathin and porous. Electrodes with this feature, placed on a hydrophilic or hydrophobic layer, will not disrupt the sensor's directional perspiration.

[0047] Step S5 of this application integrates the modules of the integrated circuit on the hydrophilic layer. By designing the wire structure (e.g., serpentine interconnect or island-bridge structure), the control circuit can maintain its electrical performance under tensile deformation.

[0048] In some embodiments, step S1 specifically includes: The first polymer and the first organic solvent are mixed to prepare spinning solution A. The resulting spinning solution A is loaded into a syringe, and the needle on the syringe is used as the spinning nozzle. The syringe is installed on an electrospinning apparatus to form an electrospinning device. Then, the distance between the electrospinning device and the receiver is adjusted, the switch of the electrospinning device is turned on, the spinning parameters are set, and electrospinning is performed. After spinning is completed, the resulting material is cooled to obtain a hydrophilic layer.

[0049] In some embodiments, in step S1, the mass percentage of the first polymer in the spinning solution A is 5-10 wt%; the first polymer includes styrene-ethylene-butene-styrene block copolymer (SEBS), and the organic solvent includes at least one of tetrahydrofuran, toluene, and cyclohexane.

[0050] In some embodiments, in step S1, the distance between the electrospinning device and the receiver is adjusted to 5-20 cm.

[0051] In some embodiments, in step S1, the spinning parameters are: the injection rate of the spinning solution is 2~10mL / h, the ambient temperature is 25~35℃, the ambient humidity is 50~70%, the voltage is 10~20kV, the needle inner diameter is 0.8~1.2mm, the rotation speed of the roller receiver is 300~500rpm, and the spinning time is 30~50min.

[0052] In some embodiments, step S2 specifically includes: The second polymer and the second organic solvent are mixed to prepare spinning solution B. The resulting spinning solution B is loaded into a syringe, and the needle on the syringe is used as the spinning nozzle. The syringe is installed on an electrospinning machine to form an electrospinning device. Then, the distance between the electrospinning device and the receiver is adjusted, the switch of the electrospinning device is turned on, the spinning parameters are set, and electrospinning is performed. After spinning is completed, the resulting material is cooled to obtain a hydrophobic layer.

[0053] In some embodiments, in step S2, the mass percentage of the second polymer in the spinning solution B is 13-23 wt%; the second polymer includes styrene-ethylene-butene-styrene block copolymer (SEBS) and polyoxyethylene polyoxypropylene ether (F127), and the mass ratio of the styrene-ethylene-butene-styrene block copolymer (SEBS) to the polyoxyethylene polyoxypropylene ether (F127) is 1:(0.6-2).

[0054] In some embodiments, in step S2, the second organic solvent includes at least one of tetrahydrofuran, toluene, and cyclohexane.

[0055] In some embodiments, step S2 adjusts the distance between the electrospinning device and the receiver to 5-20 cm.

[0056] In some embodiments, in step S2, the spinning parameters are: the pusher speed of the spinning solution is 2~10mL / h, the ambient temperature is 25~35℃, the ambient humidity is 40~70%, the spinning voltage is 10~20kV, the needle inner diameter is 0.8~1.2mm, the rotation speed of the roller receiver is 300~500rpm, and the spinning time is 30~60min.

[0057] In some embodiments, step S4, the step of preparing a patterned electrode on the sacrificial layer, includes: vapor-depositing a metal layer on the sacrificial layer, and then performing a patterning process to obtain a patterned electrode.

[0058] The vapor deposition method may include at least one of magnetron sputtering and evaporation, and the patterning method may include at least one of laser cutting and mechanical cutting.

[0059] The inventors conducted extensive research experiments during the research process, including designing and fabricating different multimodal directional perspiration sensors and testing their performance. Some experimental examples and test results are listed below to illustrate this application: Example 1 An embodiment of the multimodal directional perspiration sensor and its preparation method according to the present invention is described below, wherein the structure of the multimodal directional perspiration sensor is as follows: Figures 1-2 As shown, the multimodal directional perspiration sensor includes an electrophysiological electrode 1, a hydrophobic layer 2, a hydrophilic layer 3, an electrochemical electrode 4, and a control circuit 5. The electrophysiological electrode 1, the hydrophobic layer 2, the hydrophilic layer 3, and the electrochemical electrode 4 are arranged sequentially. The control circuit 5 is disposed on the hydrophilic layer 3. The electrophysiological electrode 1 and the electrochemical electrode 4 are respectively connected to the control circuit 5 through wires 6. There are two electrophysiological electrodes 1. The electrochemical electrode 4 includes a working electrode, a reference electrode, and an auxiliary electrode.

[0060] The control circuit 5 includes an electrophysiological acquisition module 51, an electrochemical acquisition module 52, a microcontroller 53, a signal transmission module 54, a power supply 55, a voltage regulation module 56, and a reference voltage module 57. The electrophysiological acquisition module 51 and the electrochemical acquisition module 52 are respectively connected to the microcontroller 53 through wires. The microcontroller 53 is connected to the signal transmission module 54 through wires. The power supply 55, the voltage regulation module 56, and the reference voltage module 57 are connected in sequence through wires. The power supply 55 is connected to the microcontroller 53 through wires.

[0061] The signal transmission module 54 is a Bluetooth antenna, and the microcontroller 53 is connected to a host computer (such as a mobile phone) through the microcontroller 53. The control circuit 52 also includes an encapsulation layer 58. The electrophysiological acquisition module 51, the electrochemical acquisition module 52, the microcontroller 53, the signal transmission module 54, the power supply 55, the voltage regulation module 56, and the reference voltage module 57 are located in the space formed by the encapsulation layer 58 and the hydrophilic layer 3.

[0062] The electrophysiological acquisition module 51 includes a low-noise amplifier and a first ADC analog-to-digital converter. The electrophysiological electrode 4, the low-noise amplifier, and the first ADC analog-to-digital converter are connected in sequence by wires.

[0063] The electrochemical acquisition module 52 includes a potentiostat circuit and a second ADC analog-to-digital converter. The electrochemical electrode 4, the potentiostat circuit, and the second ADC are connected in sequence by wires.

[0064] The method for preparing the multimodal directional perspiration sensor includes the following steps: S1. Preparation of the hydrophobic layer: Styrene-ethylene-butene-styrene block copolymer (SEBS) was mixed with tetrahydrofuran (THF) to prepare spinning solution A, with a content of 8 wt%. The resulting spinning solution A was loaded into a syringe, and the needle on the syringe was installed as a spinning nozzle. The syringe was then installed on an electrospinning machine to form an electrospinning device. The distance between the electrospinning device and the receiver was adjusted, the switch of the electrospinning device was turned on, the spinning parameters were set, and electrospinning was performed. After spinning was completed, the resulting material was naturally cooled to room temperature to obtain a hydrophobic layer. The mass percentage of SEBS in spinning solution A, the distance between the electrospinning device and the receiver, and the spinning parameters are shown in Table 1. S2. Preparation of the hydrophilic layer: Styrene-ethylene-butene-styrene block copolymer (SEBS), polyoxyethylene polyoxypropylene ether (F127), and tetrahydrofuran (THF) were mixed to prepare spinning solution B. The resulting spinning solution B was loaded into a syringe, and the needle on the syringe was installed as a spinning nozzle. The syringe was then installed on an electrospinning machine to form an electrospinning device. The distance between the electrospinning device and the receiver was adjusted, the switch of the electrospinning device was turned on, the spinning parameters were set, and electrospinning was performed. After spinning was completed, the resulting material was naturally cooled to room temperature to obtain a hydrophilic layer. The mass percentage of SEBS in spinning solution B, the mass percentage of F127, the distance between the electrospinning device and the receiver, and the spinning parameters are shown in Table 1. S3. Preparation of electrophysiological electrodes: Polyvinyl alcohol (PVA) and tetrahydrofuran were mixed to prepare spinning solution C, with PVA content of 10 wt%. The resulting spinning solution C was loaded into a syringe, and a needle was installed on the syringe as a spinning nozzle. The syringe was then installed on an electrospinning apparatus to form an electrospinning device. The distance between the electrospinning device and the receiver was adjusted to 15 cm. The electrospinning device was turned on, and the spinning parameters were set before electrospinning was performed. The spinning parameters were: spinning solution pusher speed 4 mL / h, ambient temperature 30℃, ambient humidity 50%, voltage 12 kV, needle inner diameter 1 mm, roller receiver rotation speed 300 rpm, and spinning time 90 min. After spinning, the resulting material is naturally cooled to room temperature to obtain the sacrificial layer; Metallic gold or platinum is deposited on the sacrificial layer using a magnetron sputtering process to form a metal layer with a thickness of 10 nm. The sacrificial layer with deposited metal is cut using a laser to obtain a patterned electrode. The obtained patterned electrode is then transferred to a hydrophobic layer, and the sacrificial layer is removed by atomization dissolution, thereby completing the setting of electrophysiological electrode 1 on hydrophobic layer 2. S4. Preparation of electrochemical electrodes: Three patterned electrodes were prepared according to step S3, and one of the electrodes was used as an auxiliary electrode. A reference electrode was prepared by printing Ag / AgCl ink on one of the electrodes using a mask screen printing process. The reference electrode, auxiliary electrode, and remaining patterned electrode were transferred onto hydrophilic layer 3. Graphene oxide powder and glucose oxidase were added to PBS buffer and thoroughly mixed to prepare a modified dispersion. The modified dispersion contained 0.1 wt% graphene oxide (no graphene oxide was required) and 0.4 wt% glucose oxidase. The modified dispersion was then added dropwise to the surface of the remaining patterned electrode using a pipette, dried at room temperature, and the addition was repeated five times to obtain the working electrode. The sacrificial layer was then removed by atomization dissolution, thus completing the setup of the electrochemical electrode 4 on hydrophilic layer 3. The hydrophilic layer with the electrochemical electrode is shown in the image. Figure 3 As shown; S5. Fabrication of wires and control circuit: A hydrophobic layer and a hydrophilic layer are stacked and positioned between the electrophysiological electrode and the electrochemical electrode. A PCB or FPCB circuit is set on the hydrophilic layer, and conductive ink is printed to form wires to connect the electrode and the circuit. At the same time, due to the porous nature of the hydrophobic and hydrophilic layers prepared by electrospinning, the printed ink can penetrate between the layers to form wires connecting the hydrophilic and hydrophobic layers. The circuit and wires are waterproofed by printing an elastic polymer coating, and the bottom of the circuit is bonded to the hydrophilic layer.

[0065] Examples 2-5 The difference between Examples 2-5 and Example 1 is that step S1 in this example changes the mass percentage of SEBS in spinning solution A and the spinning parameters, as detailed in Table 1; In step S2 of this embodiment, the mass percentages of SEBS and F127 in spinning solution B were changed, as were the spinning parameters, as detailed in Table 1.

[0066] Examples 6-7 The difference between Examples 6 and 7 and Example 1 is that step S2 in Examples 6 and 7 changes the spinning parameters, as detailed in Table 1.

[0067] In the sensor fabrication process of the above embodiments, scanning electron microscopy was used to characterize the morphology of the hydrophilic layer and the hydrophobic layer, respectively, and corresponding SEM images were obtained. A certain area, 2500 μm, was selected. 2 An area of ​​50μm × 50μm was measured, and the pore diameter, average fiber diameter, average spindle diameter, and number of spindles in this area were determined using computer software or manually. Fifty tests were conducted, and the average value was taken. The test results are shown in Tables 1-2. Figures 4-5 As shown.

[0068] In the sensor fabrication process of the above embodiment, water contact angle tests were performed on the hydrophilic layer and the hydrophobic layer respectively. The test method was as follows: water was used as the test liquid, and a contact angle tester was used to test the contact angle. When a 5μL water droplet was uniformly applied to the material surface for an instant (within 0.4s), a regular contact angle was formed.

[0069] From Tables 1-2 and Figures 4-5 As can be seen, in the various embodiments of the present invention, the hydrophilic layer has a smaller pore size, finer fibers, and a periodic spindle structure, while the hydrophobic layer has a larger pore size, coarser fibers with uniform diameter.

[0070] Table 1 Table 2 Effect test The following performance tests were performed on the sensor provided in the above embodiments: (1) The test method for liquid transport rate is as follows: The nanofiber membrane is cut into strips of 1cm×3cm, and both ends are fixed on a glass slide, leaving the central 1cm×1cm area suspended. The injection needle is placed under the fabric, and liquid is continuously injected into the nanomesh structure from the bottom at a controlled rate using an injection pump. The flow rate is gradually increased until the fabric can no longer transport all the liquid from the hydrophobic layer to the hydrophilic layer, which is the highest liquid transport rate.

[0071] (2) The test method for skin interface contact impedance is as follows: the test is carried out by an electrochemical workstation. During the test, the sensor is placed on the arm with a distance of about 4 cm between the two electrophysiological electrodes. A voltage of 50 mV is applied and the frequency range is set between 1 Hz and 1 MHz. The change of skin interface impedance with frequency is obtained by electrochemical impedance spectroscopy (EIS).

[0072] (3) Sensitivity test method: Immerse the electrochemical electrode of the sensor in PBS solution, and add the target detection substances (glucose, lactic acid, HCl, NaCl, KCl) one by one so that the mass concentration of each target detection substance in the solution is 50 μm / L, 100 μm / L, 150 μm / L, 200 μm / L, 250 μm / L, and 300 μm / L, respectively. At the same time, the change of current is measured, and finally the data set of current as the concentration of substance increases is obtained. The data is fitted to obtain the calibration curve of the target substance, and the slope of the curve is the sensitivity.

[0073] The test results are shown in Table 3 below.

[0074] Table 3 As can be seen from Table 3, the substrates composed of hydrophobic layer 2 and hydrophilic layer 3 in the various embodiments of this application achieve anti-gravity liquid transport, with the liquid transport rate in Examples 1-5 reaching 3-4 mL × min. -1 ×cm -2 It is approximately 2000 times the average human sweating rate; and the sensors provided in the embodiments of this application have low skin interface contact impedance and excellent reusability.

[0075] The sensors provided in the various embodiments of this application also exhibit excellent sensitivity; multiple sensors can sensitively detect corresponding glucose, lactic acid, and H+. + Na + K + While detecting key biomarkers, it can effectively resist interference from other sweat components, exhibiting excellent selectivity. The mean absolute error and mean absolute percentage error of the obtained data are both at low levels, demonstrating high measurement accuracy.

[0076] The embodiments of this application have been described in detail above. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A multi-modal directional sweat sensing sensor, characterized in that, The application relates to an electro-physiological electrode, a hydrophobic layer, a hydrophilic layer, an electrochemical electrode and a control circuit, wherein the electro-physiological electrode, the hydrophobic layer, the hydrophilic layer and the electrochemical electrode are sequentially arranged, the control circuit is arranged on the hydrophilic layer, the electro-physiological electrode and the electrochemical electrode are connected with the control circuit through wires, and the electrochemical electrode comprises a working electrode, a reference electrode and an auxiliary electrode.

2. The multi-modal directional sweat sensing sensor of claim 1, wherein, The control circuit comprises an electro-physiological acquisition module, an electrochemical acquisition module, a microcontroller and a signal transmission module, the electro-physiological acquisition module and the electrochemical acquisition module are connected with the microcontroller through wires, and the microcontroller is connected with the signal transmission module through wires.

3. The multi-modal directional sweat sensing sensor of claim 2, wherein, The control circuit further comprises a power supply, a voltage regulation module and a reference voltage module, the power supply, the voltage regulation module and the reference voltage module are sequentially connected through wires, and the power supply is connected with the microcontroller through wires.

4. The multi-modal directional sweat sensing sensor of claim 1, wherein, The water contact angle of the hydrophobic layer is not less than 110 degrees, and the water contact angle of the hydrophilic layer is not more than 60 degrees.

5. The multi-modal directional sweat sensing sensor of claim 1, wherein, The average pore diameter of the hydrophobic layer is larger than that of the hydrophilic layer.

6. The multi-modal directional sweat sensing sensor of claim 1, wherein, The hydrophobic layer is formed by randomly stacking fibers, and the average diameter of the fibers is 2-12 microns.

7. The multi-modal directional sweat sensing sensor of claim 1, wherein, The hydrophilic layer is formed by randomly stacking spindle fibers, the spindle fiber has a spindle and a fiber connected with the spindle, the average long-axis diameter of the spindle is 2-10 microns, and the average diameter of the fiber in the spindle fiber is 0.5-5 microns.

8. A method of making a multi-modal directional sweat sensor as claimed in any one of claims 1 to 7, characterised in that, The method comprises the following steps: S1, preparing a hydrophilic layer through an electrostatic spinning process; S2, preparing a hydrophobic layer through an electrostatic spinning process; S3, preparing a patterned electro-physiological electrode on a sacrifice layer through a magnetron sputtering process and a laser cutting process, transferring the electro-physiological electrode to the hydrophobic layer, removing the first sacrifice layer through atomization dissolution, and thus completing the arrangement of the electro-physiological electrode on the hydrophobic layer; S4, transferring the auxiliary electrode, the working electrode and the reference electrode to the hydrophilic layer respectively, removing the sacrifice layer through atomization dissolution, and thus completing the arrangement of the electrochemical electrode on the hydrophilic layer; S5, stacking the hydrophobic layer and the hydrophilic layer, and arranging the modules of the control circuit on the hydrophilic layer, and forming wires through printing of conductive ink to realize the electrical connection of the modules, and performing waterproof packaging of the modules and the wires through printing of an elastic polymer coating.

9. The method of claim 8, wherein the multimodal directional sweat sensor is prepared by, Step S1 specifically comprises the following steps: a first polymer is mixed with a first organic solvent to prepare a spinning solution A, the obtained spinning solution A is loaded into a syringe, a needle head installed on the syringe is used as a spinning nozzle, the syringe is installed on an electrostatic spinning instrument to form an electrostatic spinning device, the distance between the electrostatic spinning device and a receiver is adjusted, a switch of the electrostatic spinning device is turned on, spinning parameters are set, electrostatic spinning is performed, the obtained product is cooled after spinning, and a hydrophilic layer is obtained; the mass percentage content of the first polymer in the spinning solution A is 5-10 wt%, and the first polymer comprises a styrene-ethylene-butylene-styrene block copolymer.

10. The method of claim 8, wherein the multimodal directional sweat sensor is prepared by, The step S2 specifically comprises: mixing the second polymer with the second organic solvent to prepare a spinning solution B, loading the obtained spinning solution B into a syringe, using a needle head of the syringe as a spinning nozzle, installing the syringe on an electrostatic spinning instrument to form an electrostatic spinning device, adjusting a distance between the electrostatic spinning device and a receiver, turning on a switch of the electrostatic spinning device, setting spinning parameters, and then electrostatic spinning is performed; and after the spinning is completed, the obtained product is cooled to obtain the hydrophobic layer. In the step S2, the mass percentage content of the second polymer in the spinning solution B is 13-23 wt%; the second polymer comprises styrene-ethylene-butylene-styrene block copolymer and polyoxyethylene polyoxypropylene ether, and the mass ratio of the styrene-ethylene-butylene-styrene block copolymer to the polyoxyethylene polyoxypropylene ether is 1: (0.6-2).

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