Self-powered wearable sweat detection sensor and preparation method thereof

Abstract

The invention discloses a self-powered wearable sweat detection sensor and a preparation method thereof. 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 stacked manner, the material of the active layer comprises a silicon carbide nanometer material. The self-powered wearable sweat detection sensor provided by the invention can effectively make up for the defect of poor power generation performance of traditional silicon carbide nano-material-based moisture, overcomes the defects of poor flexibility and complex preparation process of a traditional silicon-based sensing device, can spontaneously adsorb sweat and moisture, can stably output electric energy, and has good application prospects. The human health state can be monitored in real time without an external power supply, and the ion detection sensitivity is good.

Description

Technical Field

[0001] The present invention relates to the technical field of sweat detection sensors, and particularly relates to a self-powered wearable sweat detection sensor and a preparation method thereof. Background Art

[0002] With the increasing emphasis on health management in modern society, people's demand for disease prevention and quality of life monitoring is constantly growing. In this context, sweat, as a direct product of human metabolism, the relationship between its component changes and health status has received extensive attention. In particular, the concentrations of sodium ions and potassium ions in sweat, as important indicators for evaluating the body's electrolyte balance, are of great significance for guiding individual ion supplementation strategies and preventing ion metabolic 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 new solutions for sweat component detection. These sensors can non-invasively collect sweat samples and, through built-in micro chemical sensors or biosensors, achieve real-time monitoring of sodium and potassium ion concentrations, providing great convenience for individual health monitoring. However, despite the significant technological progress of wearable sweat sensors, they still face many challenges. Currently, widely used sweat detection sensor devices 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 electronic devices. Therefore, developing a sweat detection sensor that can self-drive and does not require an external power supply has become a current research hotspot.

[0004] Humidity generator devices, as materials with unique sensitivity to humidity, provide the possibility for realizing self-powered humidity sensors. However, there are still many deficiencies in the material selection and structural design of existing humidity generator devices. For example, semiconductor nanomaterials, especially carbide nanomaterials, although they have potential power generation and sensing properties, the differences in their microscopic morphologies lead to large differences in performance, and further optimization and improvement are required. In addition, although polymer electrode materials have strong water retention properties, it is difficult for water to be released, which limits their application in the preparation of self-powered humidity sensor devices with high response speed and recovery speed. On the other hand, most traditional silicon-based humidity power generation and sensing devices use rigid hard materials, which do not match the softness and stretchability of the skin, resulting in obvious discomfort during long-term wearing. This not only affects the comfort of the sensor but also limits its wide application in daily health monitoring.

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

[0006] To solve the above technical problems, the object of the present invention is to provide a self-powered wearable sweat detection sensor and its preparation method, which utilizes the moisture power generation characteristics of the silicon carbide active layer to achieve higher output self-driven power supply, so as to ensure its reduction of dependence on external energy and make it suitable for long-term sweat detection.

[0007] The present invention is achieved through the following technical solutions:

[0008] In the first aspect of the present invention, a self-powered wearable sweat detection sensor is provided. The self-powered wearable sweat detection sensor includes a carbon nanotube fabric electrode, an active layer, and a gallium indium alloy fabric electrode stacked; the material of the active layer contains silicon carbide nanomaterials.

[0009] The carbon nanotube fabric electrode and the gallium indium alloy fabric electrode provided by the present invention form an asymmetric electrode pair. 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 nanomaterials is selected from one or more of nanoparticles, nanowires, nanopores, nanosheets, and nanocones.

[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 nanocones 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 nanomaterials are selected from one or more of bamboo-shaped silicon carbide nanowires, rod-shaped silicon carbide nanowires, and bead-shaped silicon carbide nanowires, preferably bamboo-shaped silicon carbide nanowires.

[0015] Compared with silicon carbide nanoparticles, bamboo-shaped silicon carbide nanowires have a higher specific surface area and excellent conductivity, so as to be able to generate electrical signals with a higher response rate and greater intensity.

[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 moisture and is convenient for preparing a breathable wearable sweat detection sensor.

[0017] In the second aspect of the present invention, a preparation method of the self-powered wearable sweat detection sensor described in the first aspect is provided, including 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 a carbon nanotube fabric electrode, an active layer, and a 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, it also includes the step of performing plasma treatment on the active layer.

[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 a uniform thickness.

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

[0025] Further, before immersion, it also includes the step of performing plasma treatment on the fabric, which can enhance the hydrophilicity of the fabric.

[0026] Further, after the drying treatment, it also includes the step of performing plasma treatment on the fabric, which can 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: Coat a gallium-indium alloy on one side surface of the fabric to obtain the gallium-indium alloy fabric electrode.

[0028] Further, before coating, it also includes the step of performing plasma treatment on the fabric, so that the fabric has better wettability to the gallium-indium liquid alloy.

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

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

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

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

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

[0034] Advantages of the present invention:

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

[0036] 2. The self-powered wearable sweat detection sensor provided by the present invention can effectively make up for the deficiencies of the poor power generation performance of traditional silicon carbide nanomaterial-based moisture power generation, and overcome the defects of the poor flexibility and complex preparation process of traditional silicon-based sensor devices. It can spontaneously adsorb sweat moisture, stably output electrical energy, and has good stretchability. It can be used as a new type of green energy health detection device, which can output an open-circuit voltage of 0.74V at a relative humidity of 80%, and has a good linear relationship with the current responses to sodium and potassium ions at different concentrations. Description of the Drawings

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

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

[0039] Figure 3Test result graph of the sweat (NaCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Example 1; among them, a is a schematic diagram of the relationship between sodium ion concentration and current response signal, and b is a linear correlation curve graph of the logarithm of sodium ion concentration and the current response signal of the device.

[0040] Figure 4 Test result graph of the sweat (KCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Example 1; among them, a is a schematic diagram of the relationship between potassium ion concentration and current response signal, and b is a linear correlation curve graph of the logarithm of potassium ion concentration and the current response signal of the device.

[0041] Figure 5 Test result graph of the sweat (NaCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Comparative Example 1.

[0042] Figure 6 Test result graph of the sweat (KCl solution) detection sensing performance of the self-powered flexible wearable sweat detection sensor device of Comparative Example 1. Detailed implementation manners

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of this invention herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0044] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the exemplified embodiments are not intended to limit the present invention.

[0045] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels 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 bamboo-shaped silicon carbide nanowires (with a diameter of 10 nm) in an ethanol solvent, and perform ultrasonic dissolution with the aid of an ultrasonic cleaner to obtain a bamboo-shaped silicon carbide nanomaterial dispersion with a concentration of 10 wt%. Drop the bamboo-shaped silicon carbide nanomaterial dispersion onto a fabric with a size of 1 cm × 1 cm, and peel it off after natural drying 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 × 1 cm, and subject this fabric to oxygen plasma vacuum treatment for 15 minutes to remove surface impurities and enhance its hydrophilicity; Put the aqueous carbon nanotube slurry (OCSiAl TUBALLBATT H 2 O, with a carbon nanotube concentration of 0.4 wt%) and deionized water into a 50 mL centrifuge tube at a volume ratio of 1:1, and use an ultrasonic cleaner to ultrasonically treat for 30 minutes to evenly disperse the carbon nanotubes to obtain a carbon nanotube dispersion; Immerse the fabric after oxygen plasma vacuum treatment in the carbon nanotube dispersion for 10 minutes. After ensuring that the fabric completely absorbs the carbon nanotubes, scrape off the excess carbon nanotube dispersion; Take out the impregnated fabric and place it on a heating table at 80 °C to dry until completely dry, and then perform oxygen plasma vacuum treatment for 15 minutes to further enhance its performance to obtain a carbon nanotube fabric electrode.

[0050] Subject a stretchable and breathable fabric with a size of 1 cm × 1 cm to oxygen plasma vacuum treatment for 15 min, and then coat a gallium-indium liquid alloy (the mass ratio of gallium to indium is 75:25, 99.99% (metal-based)) on one side surface to obtain a gallium-indium alloy fabric electrode.

[0051] Stack in the order of 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) to form a sandwich structure, and construct the self-powered wearable sweat detection sensor. Lead out copper wires through silver paste on the upper and lower electrodes respectively for convenient 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 × 1 cm grooves to prepare a complete and independent self-powered flexible wearable sweat detection sensor device. The structural schematic diagram is as Figure 1 shown. The overall diameter of the sensor device is 1 cm, and the height is about 2 mm. In Example 1, the active layer uses bamboo-shaped silicon carbide nanowires, which have good stability; the lower electrode contains a gallium-indium alloy liquid metal, which can form a network structure with good biocompatibility and sweat adsorption ability.

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

[0054] The power generation performance of the self-powered flexible wearable sweat detection sensor device of Example 1 was tested. The output voltage data of the sensor device at different humidities are shown in Table 1:

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

[0056]

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

[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: 6 μL of different concentrations of NaCl solutions (0.1 - 250 mM) and 6 μL of different concentrations of KCl solutions (10 - 500 mM) were respectively dropped onto the surface of the self-powered flexible wearable sweat detection sensor device, and the current responses between the upper and lower electrodes of sodium and potassium ions were recorded at different ion concentrations.

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

[0060] Example 2

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

[0062] S1. Dissolve silicon carbide nanoparticles (particle size of 10 nm) in an ethanol solvent, and perform ultrasonic dissolution with the aid of an ultrasonic cleaner to obtain a silicon carbide nanoparticle dispersion with a concentration of 10 wt%. Drop the silicon carbide nanoparticle dispersion onto a fabric with a size of 1 cm × 1 cm, and peel it off after natural drying to obtain an active layer (silicon carbide nanoparticle thin film) with a thickness of about 10 μm;

[0063] S2. Select a fabric made of plant cellulose with a size of 1 cm × 1 cm, and subject this fabric to oxygen plasma vacuum treatment for 15 minutes to remove surface impurities and enhance its hydrophilicity; Put the aqueous carbon nanotube slurry and deionized water into a 50 mL centrifuge tube at a volume ratio of 1:1, and use an ultrasonic cleaner to ultrasonically treat for 30 minutes to uniformly disperse the carbon nanotubes to obtain a carbon nanotube dispersion; Immerse the fabric after oxygen plasma vacuum treatment in the carbon nanotube dispersion for 10 minutes. After ensuring that the fabric completely absorbs the carbon nanotubes, scrape off the excess carbon nanotube dispersion; Take out the impregnated fabric and place it on a heating table at 80 °C to dry until completely dry, and then perform oxygen plasma vacuum treatment for 15 minutes to further enhance its performance to obtain a carbon nanotube fabric electrode;

[0064] Subject a stretchable and breathable fabric with a size of 1 cm × 1 cm to oxygen plasma vacuum treatment, and then coat a gallium-indium alloy on one side surface to obtain a gallium-indium alloy fabric electrode;

[0065] Stack in the order of a carbon nanotube fabric electrode (upper electrode), an active layer (silicon carbide nanoparticle thin film), and a gallium-indium alloy fabric electrode (lower electrode) to form a sandwich structure, and construct the self-powered wearable sweat detection sensor. Lead out copper wires through silver paste on the upper and lower electrodes respectively for convenient testing.

[0066] Sandwich the self-powered wearable sweat detection sensor prepared in Example 2 between a pair of PDMS films with grooves of 1 cm × 1 cm in size to prepare a complete and independent self-powered flexible wearable sweat detection sensor device for testing. The output voltage data of this sensor device at different humidities are shown in Table 2:

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

[0068]

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

[0070] Comparative Example 1

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

[0072] S1. Dissolve bamboo-shaped silicon carbide nanowires (with a diameter of 10 nm) in an ethanol solvent, and perform ultrasonic dissolution with the aid of an ultrasonic cleaner to obtain a bamboo-shaped silicon carbide nanomaterial dispersion with a concentration of 10 wt%. Drop the bamboo-shaped silicon carbide nanomaterial dispersion onto a fabric with a size of 1 cm × 1 cm, and exfoliate it 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 × 1 cm, and subject this fabric to oxygen plasma vacuum treatment for 15 minutes to remove surface impurities and enhance its hydrophilicity; put the aqueous carbon nanotube slurry and deionized water into a 50 mL centrifuge tube at a volume ratio of 1:1, and use an ultrasonic cleaner to ultrasonically treat for 30 minutes to make the carbon nanotubes disperse evenly to obtain a carbon nanotube dispersion; immerse the fabric after oxygen plasma vacuum treatment in the carbon nanotube dispersion for 10 minutes. After ensuring that the fabric completely absorbs the carbon nanotubes, scrape off the excess carbon nanotube dispersion; take out the impregnated fabric and place it on a heating table at 80 °C to dry until completely dry, and then perform oxygen plasma vacuum treatment for 15 minutes to further enhance its performance to obtain a carbon nanotube fabric electrode;

[0074] Stack in the order of a carbon nanotube fabric electrode (upper electrode), an active layer (bamboo-shaped silicon carbide nanowire film), and a carbon nanotube fabric electrode (lower electrode) to form a sandwich structure, and construct the wearable sweat detection sensor. Lead out copper wires through silver paste on the upper and lower electrodes respectively for convenient testing.

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

[0076] Test the sweat detection sensing performance of the flexible wearable sweat detection sensor device in Comparative Example 1. The test method is as follows: Drop 6 μL of different concentrations of NaCl solution (0.1 - 250 mM) and 6 μL of different concentrations of KCl solution (10 - 500 mM) onto the surface of the flexible wearable sweat detection sensor device respectively, and record the current responses between the upper and lower electrodes of sodium and potassium ions at different concentrations of sodium and potassium ions.

[0077] The test results are as Figure 5 and Figure 6As shown, it can be found that the symmetric electrode device does not have a gradient platform for ionic solutions of different concentrations, only an instantaneous response, and no obvious gradient response, probably because there is only a response to water.

[0078] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. Those skilled in the art should understand that other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A self-powered wearable sweat detection sensor, characterized in that: The self-powered wearable sweat detection sensor comprises a stacked carbon nanotube fabric electrode, an active layer and a gallium-indium alloy fabric electrode; the material of the active layer comprises silicon carbide nanomaterial.

2. The self-powered wearable sweat detection sensor according to claim 1, characterized in that: The nanostructure of the silicon carbide nanomaterial is selected from one or more of nanoparticles, nanowires, nanoholes, nanosheets and nanocones.

3. The self-powered wearable sweat detection sensor according to claim 1, characterized in that: The silicon carbide nanomaterial is selected from one or more of bamboo-shaped silicon carbide nanowires, stick-shaped silicon carbide nanowires and bead-shaped silicon carbide nanowires.

4. A method for preparing a self-powered wearable sweat detection sensor according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. dissolving a silicon carbide nanomaterial in a solvent to obtain a silicon carbide nanomaterial dispersion, coating the silicon carbide nanomaterial dispersion on a substrate to obtain an active layer on the substrate; S2. The carbon nanotube fabric electrode, the active layer, and the gallium-indium alloy fabric electrode are stacked in order to form a sandwich structure to construct the self-powered wearable sweat detection sensor.

5. The preparation method according to claim 4, characterized in that: In S1, the solvent is selected from one or more of water, methanol, ethanol and propanol.

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

7. The preparation method according to claim 4, characterized in that: S1 also includes a step of performing plasma treatment on the active layer.

8. The preparation method according to claim 4, characterized in that: In S2, the method for preparing the carbon nanotube fabric electrode comprises 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.

9. The preparation method according to claim 4, characterized in that: In S2, the method for preparing the gallium-indium alloy fabric electrode comprises the following steps: coating a gallium-indium alloy on one surface of the fabric to obtain the gallium-indium alloy fabric electrode.

10. The preparation method according to claim 9, characterized in that: The step of plasma treating the fabric is also included before coating.

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