A flexible self-driven hydrogel humidity sensor and a preparation method thereof

Abstract

The application discloses a kind of flexible self-driven hydrogel humidity sensors and preparation method thereof, the flexible self-driven hydrogel humidity sensor includes the carbon nanotube fabric electrode, functional layer and metal electrode of laminated arrangement;The functional layer includes gelatin and kappa-carrageenan.The flexible self-driven hydrogel humidity sensor provided by the application adopts self-adhesion connection mode, directly connects with electrode and skin using the high adhesion of functional layer, without additional adhesive.And, the application provides power support for equipment using moisture power generation technology, using the principle of moisture conversion into electrical energy, realizes self-powered function.This technology reduces the dependence on external power supply, improves the use convenience of equipment, ensures that the sensor can run for a long time under the condition of no external power supply, provides continuous energy support for humidity monitoring.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of humidity sensors, in particular to a flexible self-driven hydrogel humidity sensor and a preparation method thereof. BACKGROUND

[0002] With the rapid development of global technology, humidity sensors are increasingly widely used in various fields, especially in environmental monitoring, industrial production, agricultural irrigation, intelligent devices and health monitoring, especially in the fields of health monitoring and intelligent devices, humidity sensing technology plays a crucial role. Changes in human skin humidity are closely related to various physiological indicators, such as skin moisture content, sweat secretion and local environmental humidity, which can be used as important indicators to reflect the health status of the human body.

[0003] However, the current existing humidity sensors mostly use capacitive or resistive hard materials, mainly for environmental humidity monitoring or industrial applications. These sensors reflect the change in humidity by detecting the change in capacitance or resistance value, although they have certain accuracy and response speed, but there are obvious defects when in contact with the human skin. Because of the use of rigid materials, these sensors are difficult to adapt to the softness and dynamic characteristics of the skin, and long-term wear will result in poor comfort. In addition, the sensitivity of traditional humidity sensors in low humidity environments is limited, and it is difficult to accurately capture the subtle changes in skin surface humidity. Over time, changes in environmental temperature or physical damage can also affect the sensing performance, leading to a decrease in the accuracy of humidity data.

[0004] In addition, the existing technology also has significant deficiencies in flexibility and adhesion. Rigid material sensors cannot closely adhere to the skin surface, which not only affects the comfort of wearing, but also reduces the accuracy of data. At the same time, the lack of sensitivity and stability makes it difficult for the sensor to accurately capture the subtle changes in skin surface humidity. In addition, the energy consumption problem is also an important factor restricting long-term monitoring, many sensors rely on external power supply, which limits their application range in wearable devices. SUMMARY

[0005] To solve the above technical problems, the purpose of the present application is to provide a flexible self-driven hydrogel humidity sensor and a preparation method thereof, which is self-powered by humidity power generation, has good skin adhesion and high sensitivity, can realize long-term comfortable wearing and accurate humidity detection, and has a wide application prospect.

[0006] The present application is realized by the following technical solutions:

[0007] The flexible self-driven hydrogel humidity sensor provided by the present application comprises a carbon nanotube fabric electrode, a functional layer and a metal electrode arranged in a stack; and the functional layer comprises gelatin and kappa-carrageenan.

[0008] The carbon nanotube (CNT) fabric electrode and the metal electrode in the flexible self-driven hydrogel humidity sensor provided by the present application constitute an asymmetric electrode pair.

[0009] The materials of the functional layer in the flexible self-driven hydrogel humidity sensor provided by the present application are all natural organic materials that are easy to obtain, have good biocompatibility and biodegradability, and the molecular chains of gelatin and kappa-carrageenan have a spiral structure.

[0010] In addition, the porous network structure formed by the combination of gelatin and kappa-carrageenan in the functional layer can promote the conduction and adsorption of moisture, thereby generating an electrical signal. - The sulfate group of the negative group of kappa-carrageenan and the COO + group of gelatin jointly construct an efficient double-ion migration channel, which can effectively improve the separation and migration rate of ions, thereby generating high-quality electrical signals and ensuring that the sensor has a high signal-to-noise ratio when responding to changes in skin humidity.

[0011] The present application adopts gelatin and kappa-carrageenan to construct a double-network hydrogel, which has high moisture absorption and good flexibility. In the design of the sensor, the combination of carbon nanotube fabric electrode and metal electrode realizes efficient moisture power generation and sensing function. The core principle of moisture power generation is based on the constructed efficient double-ion transport channel, which uses asymmetric moisture distribution to induce charge separation. When the hydrogel absorbs the moisture on the surface of the skin, water molecules form a gradient in the hydrogel, thereby inducing asymmetric ion distribution. In this process, the double-ion transport channel can promote the rapid migration of ions, so that the charges are separated between the metal electrode and the carbon nanotube fabric electrode, generating an electrical signal. This double-ion transport channel design greatly improves the efficiency of moisture power generation, and the flexibility of the hydrogel material ensures that the sensor can be closely attached to the skin surface for a long time, not only ensuring the effectiveness of moisture absorption, but also improving the stable output of the electrical signal.

[0012] Further, the mass ratio of the gelatin and kappa-carrageenan is (3-5):(0.05-0.1).

[0013] Further, the metal electrode is a metal aluminum electrode.

[0014] The present application provides a preparation method of the flexible self-driven hydrogel humidity sensor of the first aspect, comprising the following steps:

[0015] S1. Dip the fabric in the carbon nanotube dispersion liquid, take out the dipped fabric and dry it to obtain a carbon nanotube fabric electrode;

[0016] S2. Mix water, moisturizing agent, pH adjuster, ion enhancer and kappa-carrageenan until the solution is transparent, then add gelatin, and obtain a hydrogel solution after complete dissolution, and prepare a hydrogel from the hydrogel solution;

[0017] S3. Stack the carbon nanotube fabric electrode of S1, the hydrogel of S2 and the metal electrode in order to form a sandwich structure, and construct the flexible self-driven hydrogel humidity sensor.

[0018] Further, in S1, before dipping, a step of plasma treatment of the fabric is further included to enhance the hydrophilicity of the fabric.

[0019] Further, the plasma treatment time is 6-10 min.

[0020] Further, in S1, the fabric is made of plant cellulose.

[0021] Further, in S1, the concentration of carbon nanotubes in the carbon nanotube dispersion liquid is 0.15-0.3wt%.

[0022] Further, in S1, the time for the soaking is 10-20 min, and after the fabric absorbs the carbon nanotubes completely, the excess carbon nanotube dispersion is scraped off.

[0023] Further, in S1, the drying method is to dry the soaked fabric at 70-80°C.

[0024] Further, in S1, after the drying, a step of plasma treatment of the fabric is further included.

[0025] Further, the time for the plasma treatment is 6-10 min.

[0026] Further, in S1, a step of patterning design of the obtained carbon nanotube fabric electrode is further included to ensure that the functional layer can be directly adhered to the skin.

[0027] Further, in S2, the humectant is selected from one or more of glycerol, ethylene glycol and propylene glycol.

[0028] Further, in S2, the pH regulator is selected from one or more of sodium citrate, citric acid, sodium malate and sodium lactate, and preferably sodium citrate and citric acid.

[0029] Further, in S2, the ion enhancer is selected from one or more of sodium chloride, potassium chloride and magnesium chloride.

[0030] Further, in S2, the mass ratio of the water, humectant, pH regulator, ion enhancer and κ-carrageenan in the hydrogel is (7.8-8.2):(5.8-6.2):(1-1.5):(0.88-0.96):(0.05-0.1).

[0031] Further, in S2, the concentration of the κ-carrageenan in the hydrogel is 0.1-0.5wt%.

[0032] Further, in S2, the water, glycerol, sodium citrate, sodium chloride, citric acid and κ-carrageenan are mixed at 85-95°C until the solution is transparent.

[0033] Further, in S2, the mass ratio of the gelatin and κ-carrageenan is (3-5):(0.05-0.1).

[0034] Further, in S2, after the addition of the gelatin, heating at 70-80°C for 3-4h is performed to ensure that the gelatin is completely dissolved.

[0035] Further, in S2, the hydrogel solution is poured into a mold and cooled to form the hydrogel.

[0036] Further, in S3, the metal electrode is a metal aluminum electrode.

[0037] Further, in S3, the double-sided conductive aluminum tape is made into a metal electrode.

[0038] Advantages of the present application:

[0039] 1. The flexible self-driven hydrogel humidity sensor provided by the present application adopts a self-adhesive connection method, directly connects the functional layer with the electrode and the skin by using the high adhesion of the functional layer, and does not need additional adhesive. Moreover, the present application adopts a flexible hydrogel material, which has good flexibility and comfort, can ensure that the sensor adapts to the dynamic changes of the skin, realizes long-time comfortable and close fitting, thereby improving the accuracy of humidity monitoring and the comfort of user wearing, and is especially suitable for long-time continuous skin humidity monitoring of wearable devices. The present application adopts a high-sensitivity hydrogel humidity sensing mechanism, which can effectively monitor the slight humidity fluctuation on the surface of the skin, ensure accurate perception in various humidity ranges, and improve the stability of data.

[0040] 2. The present application adopts a humidity power generation technology to provide power support for the device, realizes self-power supply function by using the principle of converting humidity into electric energy. This technology reduces the dependence on external power supply, improves the use convenience of the device, and ensures that the sensor can run for a long time under the condition of no external power supply, thereby providing continuous energy support for humidity monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Structure diagram of the flexible self-driven hydrogel humidity sensor prepared in Example 1.

[0042] Figure 2 Structure diagram of the flexible self-driven hydrogel humidity sensor prepared in Example 1 and schematic diagram of its electrical performance working principle.

[0043] Figure 3 Preparation flowchart of the gelatin / kappa-carrageenan hydrogel in Example 1.

[0044] Figure 4 Schematic diagram of the two-dimensional cross-linked network in the synthesis process of the gelatin / kappa-carrageenan hydrogel in Example 1.

[0045] Figure 5 Schematic diagram of the surface tensile of the gelatin / kappa-carrageenan hydrogel in Example 1.

[0046] Figure 6Scanning electron microscope images of cross sections of gelatin / κ-carrageenan hydrogels with different κ-carrageenan concentrations are shown; where a is a gelatin / κ-carrageenan hydrogel with a κ-carrageenan concentration of 0 wt%, b is a gelatin / κ-carrageenan hydrogel with a κ-carrageenan concentration of 0.2 wt% from Example 3, and c is a gelatin / κ-carrageenan hydrogel with a κ-carrageenan concentration of 0.4 wt% from Example 1.

[0047] Figure 7 The images show the transparency test results of the gelatin / κ-carrageenan hydrogels in Examples 1-5.

[0048] Figure 8 The figure shows the long-term electrical performance test results of the flexible self-driven hydrogel humidity sensor prepared in Example 1.

[0049] Figure 9 Figure 1 shows the test results of the electrical performance and output power of the flexible self-driven hydrogel humidity sensor prepared in Example 1 under different load resistances.

[0050] Figure 10 The image shows the electrical performance response signal of the flexible self-driven hydrogel humidity sensor prepared in Example 1, used to test the skin humidity of the palm and forehead; where a is the test result of the palm and b is the test result of the forehead.

[0051] Figure 11 The electrical performance response signal diagrams of the flexible self-driven hydrogel humidity sensor prepared in Example 1 under different skin humidity conditions are shown. Among them, a is the electrical response signal diagram of the flexible self-driven hydrogel humidity sensor in the range of 20%-70% skin humidity on the inside of the wrist, and b is the response time and recovery time data diagram of the flexible self-driven hydrogel humidity sensor. Detailed Implementation

[0052] 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 invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] The present invention provides a flexible self-driven hydrogel humidity sensor, which includes a carbon nanotube fabric electrode, a functional layer and a metal electrode stacked together; the functional layer comprises gelatin and κ-carrageenan.

[0054] In a specific embodiment, the functional layer is a hydrogel made of gelatin and κ-carrageenan (gelatin / κ-carrageenan hydrogel), which has excellent biocompatibility and moisture adsorption capacity.

[0055] In a specific embodiment, the concentration of the kappa-carrageenan in the gelatin / kappa-carrageenan hydrogel is 0.1-0.5 wt%.

[0056] In a specific embodiment, the flexible self-driven hydrogel humidity sensor comprises an asymmetric electrode combination of a carbon nanotube fabric electrode and a metal electrode, a lead wire is drawn through conductive silver paste to collect the skin humidity sensing signal.

[0057] The flexible self-driven hydrogel humidity sensor provided by the application adopts a self-adhesive connection mode, the functional layer material has good self-adhesion, the carbon nanotube fabric electrode is designed in a patterned manner, so that the sensor can be closely combined with the skin, the use of additional adhesive is avoided, and thus the comfort and stability of wearing are improved.

[0058] The application will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it, but the embodiments are not limiting to the application.

[0059] In the following examples, the experimental methods are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0060] Example 1

[0061] A preparation method of a flexible self-driven hydrogel humidity sensor comprises the following steps:

[0062] S1. A fabric made of plant cellulose is selected, the size of which is 9cmx9cm, and the fabric is subjected to oxygen plasma vacuum treatment for 6 minutes to remove surface impurities and enhance its hydrophilicity; water-based carbon nanotube paste (OCSiAl TUBALL BATT H2O, the concentration of carbon nanotube is 0.4 wt%) and deionized water are put into a 50mL centrifuge tube at a volume ratio of 1:1, and an ultrasonic cleaner is used for ultrasonic treatment for 30 minutes to uniformly disperse the carbon nanotubes, to obtain a carbon nanotube dispersion liquid; the fabric subjected to oxygen plasma vacuum treatment is immersed in the carbon nanotube dispersion liquid for 10 minutes, and after ensuring that the fabric completely absorbs the carbon nanotube, the excess carbon nanotube dispersion liquid is scraped off; the immersed fabric is taken out and dried on a heating table at 80℃ until completely dry, and then subjected to oxygen plasma vacuum treatment for 6 minutes to further enhance its performance, to obtain a carbon nanotube fabric electrode; a laser marking machine is used to cut the carbon nanotube fabric electrode into a circle with a diameter of 1cm, and a patterned design is performed, as shown in FIG. 1, to ensure that the functional layer material can be directly adhered to the skin. Figure 1

[0063] ​S2. Mix 8 mL of water, 6 g of glycerol, 1.14 g of sodium citrate, 0.92 g of sodium chloride, 0.2 g of citric acid and 0.08 g of K-carrageenan, dissolve K-carrageenan thoroughly on a heating table at 90°C until the solution is transparent, then add 4 g of gelatin, heat at 70°C for 4 hours to ensure complete dissolution of gelatin, to obtain a hydrogel solution, pour the hydrogel solution into a circular silicone mold with a diameter of 1 cm and a depth of 2 mm, and cool at room temperature for 30 minutes to form a gelatin / K-carrageenan hydrogel (the concentration of K-carrageenan in the gelatin / K-carrageenan hydrogel is 0.4 wt%).

[0064] S3. Cut a double-sided conductive aluminum adhesive tape into a circular electrode with a diameter of 1 cm using a laser marking machine to obtain a metal aluminum electrode; stack the carbon nanotube fabric electrode according to S1, the gelatin / K-carrageenan hydrogel (encapsulated with a surrounding ring of silicone film to prevent external moisture interference) according to S2, and the metal aluminum electrode in the order of sandwich structure to construct the flexible self-driven hydrogel humidity sensor.

[0065] Example 2

[0066] A method for preparing a flexible self-driven hydrogel humidity sensor, which is basically the same as that of Example 1, except that in S2, the concentration of K-carrageenan in the gelatin / K-carrageenan hydrogel is 0.1 wt%.

[0067] Example 3

[0068] A method for preparing a flexible self-driven hydrogel humidity sensor, which is basically the same as that of Example 1, except that in S2, the concentration of K-carrageenan in the gelatin / K-carrageenan hydrogel is 0.2 wt%.

[0069] Example 4

[0070] A method for preparing a flexible self-driven hydrogel humidity sensor, which is basically the same as that of Example 1, except that in S2, the concentration of K-carrageenan in the gelatin / K-carrageenan hydrogel is 0.3 wt%.

[0071] Example 5

[0072] A method for preparing a flexible self-driven hydrogel humidity sensor, which is basically the same as that of Example 1, except that in S2, the concentration of K-carrageenan in the gelatin / K-carrageenan hydrogel is 0.5 wt%.

[0073] Figure 1A structural schematic diagram of the flexible self-driven hydrogel humidity sensor prepared in Example 1 is shown, including a schematic diagram of the patterned design of the carbon nanotube fabric electrode, which is precisely patterned by laser direct writing technology. This design ensures that the functional layer material (gelatin / k-carrageenan hydrogel) can directly contact the skin to achieve good fit performance. The -OH and other functional groups in the gelatin / k-carrageenan hydrogel form hydrogen bonds with the molecules on the surface of the skin, further enhancing the self-adhesion performance.

[0074] A structural schematic diagram of the flexible self-driven hydrogel humidity sensor prepared in Example 1 and a schematic diagram of its electrical performance working principle are shown in Figure 2 , the overall diameter of the humidity sensor is 1 cm, and the height is about 2 mm. The functional layer uses a combination of natural gelatin and k-carrageenan to form a porous network with good biocompatibility and moisture absorption capacity. In addition, the sensor realizes a humidity gradient-driven response mechanism by designing an asymmetric humidity distribution. The gelatin / k-carrageenan hydrogel as a functional layer material contains charged groups such as COO - , NH3 + and OSO3 - in its molecular structure. These groups can build efficient ion migration channels under humidity changes, thereby improving the effective ion transmigration rate, significantly reducing energy loss due to ineffective diffusion, and improving the separation efficiency of positive and negative ions.

[0075] A schematic diagram of the preparation process of the gelatin / k-carrageenan hydrogel in Example 1 is shown in Figure 3 . This hydrogel has a rich helical molecular structure, which as a good energy dissipation mechanism significantly improves the tensile properties and mechanical strength of the material. A schematic diagram of the two-dimensional cross-linked network during the synthesis of the gelatin / k-carrageenan hydrogel in Example 1 is shown in Figure 4 . In this network, the k-carrageenan molecules form stable electrostatic cross-linking with the amino groups (NH3 + ) and carboxyl groups (COO - ) in the gelatin molecules through their sulfate groups (OSO3 - ). In addition, the -OH and -NH groups between the gelatin and k-carrageenan molecules further form auxiliary cross-linking points through hydrogen bonding. This composite cross-linked network significantly enhances the mechanical properties of the hydrogel, providing excellent tensile resistance and energy dissipation capacity while maintaining good flexibility.

[0076] Figure 5A schematic diagram of the surface stretching of the gelatin / κ-carrageenan hydrogel in Example 1, which has remarkable surface stretching performance and can achieve a strain rate of up to 700%. This excellent tensile property is mainly due to the synergistic effect of the dynamic cross-linking network inside the material, including the electrostatic cross-linking and hydrogen bond cross-linking structure between κ-carrageenan and gelatin molecules. The cross-linking network can dynamically reorganize under external force, providing an efficient energy dissipation mechanism to ensure the structural integrity and functional stability of the material under large deformation conditions.

[0077] Figure 6 Scanning electron microscope images of the cross-section of the gelatin / κ-carrageenan hydrogel with different κ-carrageenan concentrations; wherein a is the gelatin / κ-carrageenan hydrogel with a κ-carrageenan concentration of 0wt%, b is the gelatin / κ-carrageenan hydrogel with a κ-carrageenan concentration of 0.2wt% in Example 3, and c is the gelatin / κ-carrageenan hydrogel with a κ-carrageenan concentration of 0.4wt% in Example 1. Figure 6 As shown in c, the smallest pores and significantly increased cross-linking density are shown. With the increase of κ-carrageenan concentration, the intermolecular cross-linking points in the hydrogel increase significantly, resulting in a more compact network structure.

[0078] Figure 7 The transparency test results of the gelatin / κ-carrageenan hydrogel in Examples 1-5 are shown in the figure from Figure 7 As can be seen from the figure, under different κ-carrageenan concentrations, the hydrogel shows a high light transmittance (more than 80%).

[0079] The electrode part of the sensor provided by the embodiment of the application is composed of a carbon nanotube fabric electrode and a metal aluminum electrode, forming an asymmetric electrode pair. The design of the sensor utilizes asymmetric humidity distribution to induce the directional migration of water in the hydrogel. The treated carbon nanotube fabric electrode has excellent hydrophilic properties, enhancing the adsorption and migration of water. The improvement of ion migration efficiency is mainly due to the charged groups on the molecular chains of gelatin and κ-carrageenan, wherein the gelatin contains positively charged amino groups (–NH3 + ) and negatively charged carboxyl groups (–COO-), and the κ-carrageenan has negatively charged sulfate groups (–SO4 - ). These charged groups promote ion migration through electrostatic interaction, building an efficient double-ion migration channel, thereby generating a strong electrical signal. This design not only improves the sensitivity and signal-to-noise ratio of the sensor, but also ensures that the sensor can closely adhere to the skin surface, adapt to the dynamic changes of the skin, and realize real-time and accurate monitoring of the skin humidity.

[0080] The flexible self-driven hydrogel humidity sensor prepared in Example 1 was subjected to electrical signal testing. The testing method was as follows: a Keithley 2440 digital source meter, alligator clip test line, and digital temperature and humidity meter were used to test the open-circuit voltage of the flexible self-driven hydrogel humidity sensor (i.e., the humidity power generation device) under long-term outdoor environment. During the test, the open-circuit voltage measurement interval of the digital source meter was set to 1000 ms, and the device was continuously monitored in an outdoor environment.

[0081] Figure 8 The long-term electrical performance test results of the flexible self-driven hydrogel humidity sensor prepared in Example 1 are shown in the graph from Figure 8 It can be seen that the sensor can continuously and stably work for more than 1200 hours under an open-circuit voltage of 1.2V, showing excellent stability and durability.

[0082] Figure 9 The electrical performance and output power test results of the flexible self-driven hydrogel humidity sensor prepared in Example 1 under different load resistances are shown in the graph from Figure 9 It can be seen that the output power of the sensor under the optimized load condition can reach 120 microwatts per square centimeter, showing excellent energy conversion efficiency. This performance is due to the efficient ion migration channels and stable cross-linked network structure of the hydrogel material, ensuring the high stability and consistency of the current generation and power output under humidity changes.

[0083] Figure 10 The electrical performance response signal graph of the flexible self-driven hydrogel humidity sensor prepared in Example 1 for testing the skin humidity of the palm and forehead is shown. After the original signal is differentiated and low-pass filtered, the results clearly show the significant difference in humidity signals of different parts. This indicates that the sensor can sensitively identify the skin humidity changes of different parts of the human body. This ability is due to the high sensitivity and low noise characteristics of the sensor, as well as the optimized ion migration channels in the hydrogel material.

[0084] Figure 11 The electrical performance response signal graph of the flexible self-driven hydrogel humidity sensor prepared in Example 1 under different skin humidity conditions is shown. After the test data is differentiated and low-pass filtered, the results show that the electrical signal response of the sensor significantly increases with the increase of skin humidity. This trend indicates that the sensor has high sensitivity and good response characteristics to humidity changes, with a response time and recovery time of 1.2 seconds and 0.9 seconds, respectively. The test environment humidity is controlled at about 30%, ensuring that the influence of external factors on the experimental results is minimized.

[0085] From Figure 10 and Figure 11It can be seen that the flexible self-driven hydrogel humidity sensor prepared by the present application shows more sensitive response to the change of humidity concentration compared with the traditional humidity sensor, and the difference of the electrical signal response of the sensor under different skin humidity conditions at different positions; under the same position and different skin humidity conditions, the electrical signal response of the sensor has significant difference, which can effectively reflect the change of skin surface humidity. This performance provides a reliable solution for real-time monitoring of skin humidity, and shows the wide potential of the sensor in practical application.

[0086] In summary, the flexible self-driven hydrogel skin humidity sensor provided by the present application can produce significant difference in electrical response signal under different skin humidity conditions. Combined with the post-processing platform, accurate and effective detection of the signal obtained by the humidity sensor can be realized, which provides a scientific basis for daily skin care and health management.

[0087] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments 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, it is not necessary and impossible to enumerate all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A flexible self-powered hydrogel humidity sensor, characterized in that, The flexible self-driven hydrogel humidity sensor comprises a carbon nanotube fabric electrode, a functional layer and a metal electrode which are stacked; the functional layer comprises gelatin and kappa-carrageenan, and the mass ratio of the gelatin and kappa-carrageenan is (3-5):(0.05-0.1). 2.The flexible self-driven hydrogel humidity sensor according to claim 1, wherein, The metal electrode is a metal aluminum electrode.

3. A method for preparing the flexible self-driven hydrogel humidity sensor according to any one of claims 1-2, characterized in that, The method comprises the following steps: S1. The fabric is immersed in a carbon nanotube dispersion solution, and the immersed fabric is taken out and dried to obtain a carbon nanotube fabric electrode; S2. Water, a moisturizing agent, a pH regulator, an ion enhancer and kappa-carrageenan are mixed until the solution is transparent, then gelatin is added, and a hydrogel solution is obtained after complete dissolution, and the hydrogel solution is made into a hydrogel; S3. The carbon nanotube fabric electrode of S1, the hydrogel of S2 and the metal electrode are stacked in order to form a sandwich structure, and the flexible self-driven hydrogel humidity sensor is constructed.

4. The production method according to claim 3, characterized by, In S1, the concentration of carbon nanotubes in the carbon nanotube dispersion solution is 0.15-0.3 wt%.

5. The preparation method according to claim 3, characterized in that, In S1, the obtained carbon nanotube fabric electrode is further subjected to a patterning design step.

6. The preparation method according to claim 3, characterized in that, In S2, the mass ratio of the water, the moisturizing agent, the pH regulator, the ion enhancer and the kappa-carrageenan is (7.8-8.2):(5.8-6.2):(1-1.5):(0.88-0.96):(0.05-0.1).

7. The preparation method according to claim 3, characterized in that, In S2, the pH regulator is selected from one or more of sodium citrate, citric acid, sodium malate and sodium lactate; and the ion enhancer is selected from one or more of sodium chloride, potassium chloride and magnesium chloride.

8. The production method according to claim 3, characterized by, In S2, the concentration of kappa-carrageenan in the hydrogel is 0.1-0.5 wt%.

9. The production method according to claim 3, characterized by, In S2, after the gelatin is added, heating is performed at 70-80 ℃ for 3-4 h.

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