A self-powered wearable sweat detection sensor and a preparation method thereof

Abstract

The application discloses a self-powered wearable sweat detection sensor and a preparation method thereof, and the self-powered wearable sweat detection sensor comprises a carbon nanotube fabric electrode, an active layer and a gallium-indium alloy fabric electrode which are arranged in a stack; and the material of the active layer comprises silicon carbide nanomaterials. The self-powered wearable sweat detection sensor can effectively make up for the poor performance of the traditional silicon carbide nanomaterial-based moisture power generation, overcome the defects of poor flexibility and complex preparation process of the traditional silicon-based sensor device, spontaneously adsorb sweat moisture, stably output electric energy, and can be used for real-time monitoring of the human health status without an external power supply, and has good ion detection sensitivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sweat detection sensor, in particular to a self-powered wearable sweat detection sensor and a preparation method thereof. BACKGROUND

[0002] With the increasing emphasis on health management in modern society, the demand for disease prevention and quality of life monitoring is growing. In this context, sweat, as a direct product of human metabolism, has attracted widespread attention due to its relationship between composition changes and health status. In particular, the concentration of sodium and potassium ions in sweat, as important indicators for assessing electrolyte balance in the body, has important significance for guiding individual ion supplementation strategies and preventing ion metabolism disorders.

[0003] Traditional sweat detection methods often rely on laboratory analysis, which is not only cumbersome to operate, but also difficult to achieve real-time monitoring. In recent years, with the rapid development of wearable technology, wearable sweat sensors have provided a new solution for sweat composition detection. These sensors can non-invasively collect sweat samples and achieve real-time monitoring of sodium and potassium ion concentrations through built-in micro-chemical sensors or biological sensors, providing great convenience for individual health monitoring. However, despite the significant progress in wearable sweat sensors, there are still many challenges. Currently widely used sweat detection sensors generally require external power supply, which not only increases the complexity and cost of the device, but also limits its further development in the field of wearable flexible electronics. Therefore, developing a self-driven sweat detection sensor without external power supply has become a hot research topic.

[0004] Humidity power generation devices, as a material with unique sensitivity to humidity, provide the possibility of realizing self-driven humidity sensors. However, existing humidity power generation devices still have many shortcomings in material selection and structure design. For example, semiconductor nanomaterials, especially carbide nanomaterials, have potential power generation and sensing performance, but the differences in their micro-morphology lead to large performance differences, which need to be further optimized and improved. In addition, although polymer electrode materials have strong water retention performance, water is difficult to release, which limits their application in the preparation of self-driven humidity sensor devices with high response speed and recovery speed. On the other hand, traditional silicon-based humidity power generation sensing devices mostly use rigid hard materials, which do not match the softness and stretchability of the skin, resulting in obvious discomfort when worn for a long time. This not only affects the comfort of the sensor, but also limits its widespread application in daily health monitoring.

[0005] Therefore, developing a wearable sweat detection sensor with self-driving capability, high sensitivity, and good comfort is of great significance for promoting the development of sweat detection technology. SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a self-powered wearable sweat detection sensor and a preparation method thereof, which utilizes the humidity power generation characteristics of the silicon carbide active layer to achieve higher output self-driven power supply, thereby reducing the dependence on external energy and making it suitable for long-term sweat detection.

[0007] The present application is realized by the following technical solutions:

[0008] The present application provides a self-powered wearable sweat detection sensor, which comprises a carbon nanotube fabric electrode, an active layer and a gallium-indium alloy fabric electrode arranged in layers; the material of the active layer comprises a silicon carbide nanomaterial.

[0009] The carbon nanotube fabric electrode and the gallium-indium alloy fabric electrode provided by the present application form an asymmetric electrode pair, and compared with traditional silicon-based devices, the gallium-indium alloy fabric electrode has better stretchability and biocompatibility.

[0010] Further, the nanostructure of the silicon carbide nanomaterial is selected from one or more of nanoparticles, nanowires, nanopores, nanosheets and nanotapers.

[0011] Further, the particle size of the nanoparticles is 1-100 nm, the diameter of the nanowires is 1-100 nm, and the size of the nanotapers is 1-100 nm.

[0012] Further, the pore size of the nanopores is 50-900 nm.

[0013] Further, the size of the nanosheets is 1-100 μm.

[0014] Further, the silicon carbide nanomaterial is selected from one or more of bamboo-shaped silicon carbide nanowires, stick-shaped silicon carbide nanowires and string-bead-shaped silicon carbide nanowires, and is preferably bamboo-shaped silicon carbide nanowires.

[0015] Compared with silicon carbide nanoparticles, bamboo-shaped silicon carbide nanowires have higher specific surface area and excellent electrical conductivity, thereby being able to generate higher response rate and stronger electrical signals.

[0016] Further, the carbon nanotube fabric electrode and / or the gallium-indium alloy fabric electrode is a porous electrode, which is beneficial to the penetration and evaporation of water, and facilitates the preparation of a breathable wearable sweat detection sensor.

[0017] The present application provides a preparation method of the self-powered wearable sweat detection sensor of the first aspect, comprising the following steps:

[0018] S1. Dissolve the silicon carbide nanomaterial in a solvent to obtain a silicon carbide nanomaterial dispersion, and coat the silicon carbide nanomaterial dispersion on a substrate to obtain an active layer on the substrate;

[0019] S2. Stack in the order of carbon nanotube fabric electrode, active layer, and gallium-indium alloy fabric electrode to form a sandwich structure, and construct the self-powered wearable sweat detection sensor.

[0020] Further, in S1, the solvent is selected from one or more of water, methanol, ethanol, and propanol.

[0021] Further, in S1, the thickness of the active layer is 5-100 μm, preferably 10-30 μm.

[0022] Further, in S1, a step of plasma treating the active layer is further included.

[0023] Further, in S1, the substrate is a fabric, and a porous fabric substrate is selected to facilitate drop coating to form an effective active layer with uniform thickness.

[0024] Further, in S2, the preparation method of the carbon nanotube fabric electrode includes the following steps: immersing the fabric in a carbon nanotube dispersion, and taking out the immersed fabric and performing drying treatment to obtain the carbon nanotube fabric electrode.

[0025] Further, before immersion, a step of plasma treating the fabric is further included to enhance the hydrophilicity of the fabric.

[0026] Further, after drying treatment, a step of plasma treating the fabric is further included to make the carbon nanotube fabric electrode more hydrophilic.

[0027] Further, in S2, the preparation method of the gallium-indium alloy fabric electrode includes the following steps: coating a gallium-indium alloy on one side surface of the fabric to obtain the gallium-indium alloy fabric electrode.

[0028] Further, before coating, a step of plasma treating the fabric is further included to make the fabric have better wettability to the liquid gallium-indium alloy.

[0029] Further, in S2, the active layer is arranged on the side of the gallium-indium alloy fabric electrode on which the gallium-indium alloy is coated.

[0030] After optimization, the power generation performance and sensing performance of the self-powered wearable sweat detection sensor provided by the application are greatly improved.

[0031] The self-powered wearable sweat detection sensor provided by the application can also be used as a moisture power generation device in the field of new energy.

[0032] The working principle of the self-powered wearable sweat detection sensor provided by the application is as follows: when water is in contact with the silicon carbide nanomaterial, the silicon carbide nanomaterial with a negative charge on the surface will attract positive charges (i.e., hydrogen ions) in the water, and a double electric layer is formed between the material surface and the liquid. In the sensor structure designed in the application, the upper electrode is exposed to a high-humidity environment and maintains a high humidity; while the lower electrode is in a state similar to being closed and maintains a low humidity, and there is a humidity difference between the upper and lower electrodes, so that a humidity gradient is formed on the upper and lower surfaces of the active layer. Due to the existence of the humidity gradient, water spontaneously migrates from the area with high humidity to the area with low humidity, and in this process, the humidity gradient promotes the flow of the liquid, and the free charged particles in the double electric layer move along the direction of the liquid flow, resulting in different degrees of charge accumulation on the upper and lower electrodes, and thus a potential difference (i.e., a streaming potential) is formed between the upper and lower electrodes, realizing self-driven power supply.

[0033] The self-powered wearable sweat detection sensor provided by the application is sandwiched between a pair of PDMS films to prepare a complete and independent self-powered flexible wearable sweat detection sensor device, and the power generation performance and sweat detection sensing performance of the device can be tested.

[0034] The application has the following beneficial effects:

[0035] 1. The self-powered wearable sweat detection sensor provided by the application can monitor the human health status in real time without an external power supply in the process of converting sweat chemical potential energy into electrical energy, and has good ion detection sensitivity.

[0036] 2. The self-powered wearable sweat detection sensor provided by the application can effectively make up for the poor performance of the traditional silicon carbide nanomaterial-based humidity power generation, and overcome the defects of poor flexibility and complex preparation process of the traditional silicon-based sensor device, can spontaneously adsorb sweat humidity, and can stably output electrical energy, and has good stretchability, can be used as a new type of green energy health detection device, can output 0.74V open circuit voltage when the relative humidity is 80%, and the current response to different concentrations of sodium and potassium ions has a good linear relationship. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the self-powered flexible wearable sweat detection sensor device of Example 1; wherein a is a whole diagram, and b is a schematic diagram of each layer structure.

[0038] Figure 2 It is a scanning electron microscope image of the bamboo-shaped silicon carbide nanowire in Example 1.

[0039] Figure 3The test results of the sweat (NaCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Example 1 are shown in the figure; wherein a is a schematic diagram of the relationship between the sodium ion concentration and the current response signal, and b is a linear correlation curve diagram of the logarithm of the sodium ion concentration and the current response signal of the device.

[0040] Figure 4 The test results of the sweat (KCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Example 1 are shown in the figure; wherein a is a schematic diagram of the relationship between the potassium ion concentration and the current response signal, and b is a linear correlation curve diagram of the logarithm of the potassium ion concentration and the current response signal of the device.

[0041] Figure 5 The test results of the sweat (NaCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Comparative Example 1 are shown in the figure.

[0042] Figure 6 The test results of the sweat (KCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Comparative Example 1 are shown in the figure. DETAILED DESCRIPTION

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0044] The present application will be further described with reference to the drawings and specific examples in order to better enable those skilled in the art to understand and practice the application, but the examples are not intended to limit the application.

[0045] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0046] Example 1

[0047] A preparation method of a self-powered wearable sweat detection sensor, comprising the following steps:

[0048] S1. Dissolve the bamboo-shaped silicon carbide nanowires (10 nm in diameter) in an ethanol solvent, and perform ultrasonic dissolution by means of an ultrasonic cleaner to obtain a bamboo-shaped silicon carbide nanomaterial dispersion liquid with a concentration of 10 wt%; drop coat the bamboo-shaped silicon carbide nanomaterial dispersion liquid on a fabric with a size of 1 cm x 1 cm, and after natural drying, peel off to obtain an active layer (bamboo-shaped silicon carbide nanowire film) with a thickness of about 10 μm;

[0049] S2. Select a fabric made of plant cellulose with a size of 1 cm x 1 cm, and subject the fabric to oxygen plasma vacuum treatment for 15 minutes to remove surface impurities and enhance hydrophilicity; place water-based carbon nanotube slurry (OCSiAl TUBALL BATT H2O, with a concentration of 0.4 wt% of carbon nanotubes) and deionized water in a 50 mL centrifuge tube at a volume ratio of 1:1, and perform ultrasonic treatment for 30 minutes by means of an ultrasonic cleaner to uniformly disperse the carbon nanotubes, thereby obtaining a carbon nanotube dispersion liquid; immerse the fabric subjected to oxygen plasma vacuum treatment in the carbon nanotube dispersion liquid for 10 minutes, and after ensuring that the fabric has completely absorbed the carbon nanotubes, scrape off the excess carbon nanotube dispersion liquid; take out the immersed fabric and dry it on a heating table at 80°C until completely dry, and then perform oxygen plasma vacuum treatment for 15 minutes to further enhance performance, thereby obtaining a carbon nanotube fabric electrode;

[0050] subject the stretchable and breathable fabric with a size of 1 cm x 1 cm to oxygen plasma vacuum treatment for 15 min, and then coat gallium-indium liquid alloy (with a mass ratio of gallium to indium of 75:25, 99.99% (metal base)) on one side surface, thereby obtaining a gallium-indium alloy fabric electrode;

[0051] Stack the carbon nanotube fabric electrode (upper electrode), the active layer (bamboo-shaped silicon carbide nanowire film), and the gallium-indium alloy fabric electrode (lower electrode) in the order of upper electrode, active layer, and lower electrode to form a sandwich structure, and construct the self-powered wearable sweat detection sensor, and draw copper wires from the upper and lower electrodes by means of silver paste, thereby facilitating testing.

[0052] Sandwich the self-powered wearable sweat detection sensor prepared in Example 1 between a pair of polydimethylsiloxane (PDMS) films with a size of 1 cm x 1 cm and a groove, thereby preparing a complete and independent self-powered flexible wearable sweat detection sensor device, and the structure is as shown in Figure 1 The overall diameter of the sensor device is 1 cm, and the height is about 2 mm. The active layer in Example 1 adopts bamboo-shaped silicon carbide nanowires, which have good stability. The lower electrode contains gallium-indium alloy liquid metal, which can form a network structure with good biocompatibility and sweat absorption capacity.

[0053] The scanning electron microscope image of the bamboo-shaped silicon carbide nanowires in Example 1 is as shown in Figure 2 .

[0054] The power generation performance of the self-powered flexible wearable sweat detection sensor device of Example 1 was tested, and the output voltage data of the sensor device under different humidity is shown in Table 1:

[0055] Table 1 Output voltage values of the self-powered flexible wearable sweat detection sensor device under different humidity

[0056]

[0057] As can be seen from Table 1, under the condition of 80% humidity, the maximum open circuit voltage of the self-powered flexible wearable sweat detection sensor device is 0.74V.

[0058] The sweat detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Example 1 was tested. The test method was as follows: 6μL of different concentrations of NaCl solution (0.1-250mM) and 6μL of different concentrations of KCl solution (10-500mM) were added to the surface of the self-powered flexible wearable sweat detection sensor device, and the current response between the sodium and potassium electrodes under different concentrations of sodium and potassium ions was recorded.

[0059] The test results are shown in Figure 3 and Figure 4 As can be seen from a in Figure 3 and b in Figure 4 , the current has different gradient responses to solutions of different ion concentrations. As can be seen from b in Figure 3 and b in Figure 4 , the logarithm of the concentration of sodium and potassium ions has a linear relationship with the current measurement value of the sensor. The linear regression equation of sodium ions is I=0.02461*lg(c Na + )+0.0603, and the linear regression equation of potassium ions is I=0.09207*lg(c K + )+0.1098. In subsequent sweat detection, the real-time concentration of sodium and potassium ions in sweat can be calculated according to the linear regression equation through the current detected in the wearable sensing device.

[0060] Example 2

[0061] A method for preparing a self-powered wearable sweat detection sensor, comprising the following steps:

[0062] S1. Silicon carbide nanoparticles (particle size 10 nm) were dissolved in an ethanol solvent, ultrasonic dissolution was carried out by means of an ultrasonic cleaner, and a silicon carbide nanoparticle dispersion liquid with a concentration of 10 wt% was obtained. The silicon carbide nanoparticle dispersion liquid was drop-coated on a fabric with a size of 1 cm x 1 cm, and after natural drying, the active layer (silicon carbide nanoparticle film) with a thickness of about 10 μm was peeled off;

[0063] S2. A fabric made of plant cellulose with a size of 1 cm x 1 cm was selected, and the fabric was treated by oxygen plasma vacuum for 15 minutes to remove surface impurities and enhance its hydrophilicity. A water-based carbon nanotube slurry was placed in a 50 mL centrifuge tube with deionized water at a volume ratio of 1:1, and ultrasonic treatment was performed for 30 minutes using an ultrasonic cleaner to uniformly disperse the carbon nanotubes, obtaining a carbon nanotube dispersion liquid. The fabric treated by oxygen plasma vacuum was immersed in the carbon nanotube dispersion liquid for 10 minutes, and after ensuring that the fabric completely absorbed the carbon nanotubes, the excess carbon nanotube dispersion liquid was scraped off. The immersed fabric was taken out and dried on a heating table at 80°C until completely dry, and then treated by oxygen plasma vacuum for 15 minutes to further enhance its performance, obtaining a carbon nanotube fabric electrode;

[0064] A stretchable and breathable fabric with a size of 1 cm x 1 cm was treated by oxygen plasma vacuum, and then a gallium-indium alloy was coated on one side of the surface to obtain a gallium-indium alloy fabric electrode;

[0065] The carbon nanotube fabric electrode (upper electrode), the active layer (silicon carbide nanoparticle film), and the gallium-indium alloy fabric electrode (lower electrode) were stacked in the order of sandwich structure to construct the self-powered wearable sweat detection sensor, and copper wires were led out from the upper and lower electrodes by silver paste for convenient testing.

[0066] The self-powered wearable sweat detection sensor prepared in Example 2 was sandwiched between a pair of PDMS film with a size of 1 cm x 1 cm recess, and a complete and independent self-powered flexible wearable sweat detection sensor device was prepared for testing. The output voltage data of the sensor device under different humidity is shown in Table 2:

[0067] Table 2 Output voltage values of the self-powered flexible wearable sweat detection sensor device under different humidity

[0068]

[0069] As can be seen from Table 2, when silicon carbide nanoparticles are used as the active layer, the open circuit voltage under 100% humidity is only 0.5 V, which is lower than the highest open circuit voltage of 0.74 V of the bamboo-shaped silicon carbide, because the bamboo-shaped silicon carbide nanowire has a larger specific surface area and more water adsorption and dissociation sites.

[0070] Comparative Example 1

[0071] A preparation method of a wearable sweat detection sensor, comprising the following steps:

[0072] S1. Dissolve the bamboo-shaped silicon carbide nanowires (10 nm in diameter) in an ethanol solvent, and perform ultrasonic dissolution by means of an ultrasonic cleaner to obtain a bamboo-shaped silicon carbide nanomaterial dispersion liquid with a concentration of 10 wt%; drop coat the bamboo-shaped silicon carbide nanomaterial dispersion liquid on a fabric with a size of 1 cm x 1 cm, and peel off after natural drying to obtain an active layer (bamboo-shaped silicon carbide nanowire film) with a thickness of about 10 μm;

[0073] S2. Select a fabric made of plant cellulose with a size of 1 cm x 1 cm, and perform oxygen plasma vacuum treatment on the fabric for 15 minutes to remove surface impurities and enhance the hydrophilicity thereof; place water-based carbon nanotube slurry and deionized water in a 50 mL centrifuge tube at a volume ratio of 1:1, and perform ultrasonic treatment by means of an ultrasonic cleaner for 30 minutes to uniformly disperse the carbon nanotubes, thereby obtaining a carbon nanotube dispersion liquid; immerse the fabric subjected to oxygen plasma vacuum treatment in the carbon nanotube dispersion liquid for 10 minutes, and scrape off the excess carbon nanotube dispersion liquid after ensuring that the fabric has completely absorbed the carbon nanotubes; take out the immersed fabric and dry it on a heating table at 80°C until completely dry, and then perform oxygen plasma vacuum treatment for 15 minutes to further enhance the performance of the fabric, thereby obtaining a carbon nanotube fabric electrode;

[0074] Stack the carbon nanotube fabric electrode (upper electrode), the active layer (bamboo-shaped silicon carbide nanowire film), and the carbon nanotube fabric electrode (lower electrode) in this order to form a sandwich structure, and construct the wearable sweat detection sensor; and draw copper wires from the upper and lower electrodes by means of silver paste, thereby facilitating testing.

[0075] Sandwich the wearable sweat detection sensor prepared in Comparative Example 1 between a pair of PDMS films with a size of 1 cm x 1 cm and recessed grooves, to prepare a complete and independent flexible wearable sweat detection sensor device.

[0076] Test the sweat detection performance of the flexible wearable sweat detection sensor device of Comparative Example 1, by the following method: drop 6 μL of NaCl solutions with different concentrations (0.1-250 mM) and 6 μL of KCl solutions with different concentrations (10-500 mM) on the surface of the flexible wearable sweat detection sensor device, and record the current response between the upper and lower electrodes of sodium and potassium ions under different concentrations of sodium and potassium ions.

[0077] The test results are shown in Figure 5 and Figure 6As shown, it can be found that the symmetric electrode device does not have a gradient platform for different concentrations of ion solution, only has an instantaneous response, and has no obvious gradient response, which may be because only the response to water.

[0078] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation manners of the present application. Those skilled in the art should understand that on the basis of the above description, other different forms of changes or variations can also be made. Here, all the implementation manners are not required or can not be exhausted. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A self-powered wearable sweat detection sensor, characterized in that, The self-powered wearable sweat detection sensor includes a stacked carbon nanotube fabric electrode, an active layer, and a gallium-indium alloy fabric electrode; the active layer is made of silicon carbide nanomaterials; the silicon carbide nanomaterials are selected from one or more of bamboo-shaped silicon carbide nanowires, rod-shaped silicon carbide nanowires, and beaded silicon carbide nanowires.

2. A method for preparing the self-powered wearable sweat detection sensor according to claim 1, characterized in that, Includes the following steps: S1. Dissolve silicon carbide nanomaterials in a solvent to obtain a silicon carbide nanomaterial dispersion, and coat the silicon carbide nanomaterial dispersion onto a substrate to obtain an active layer on the substrate; S2. The self-powered wearable sweat detection sensor is constructed by stacking carbon nanotube fabric electrodes, active layer, and gallium indium alloy fabric electrodes in sequence to form a sandwich structure.

3. The preparation method according to claim 2, characterized in that, In S1, the solvent is selected from one or more of water, methanol, ethanol and propanol.

4. The preparation method according to claim 2, characterized in that, In S1, the thickness of the active layer is 5-100 μm.

5. The preparation method according to claim 2, characterized in that, S1 also includes a step of plasma treatment of the active layer.

6. The preparation method according to claim 2, characterized in that, In S2, the preparation method of the carbon nanotube fabric electrode includes the following steps: immersing the fabric in a carbon nanotube dispersion, taking out the immersed fabric and drying it to obtain the carbon nanotube fabric electrode.

7. The preparation method according to claim 2, characterized in that, In S2, the method for preparing the gallium-indium alloy fabric electrode includes the following steps: coating a gallium-indium alloy on one side surface of the fabric to obtain the gallium-indium alloy fabric electrode.

8. The preparation method according to claim 7, characterized in that, The process also includes plasma treatment of the fabric prior to coating.

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