A self-powered flexible moisture sensor based on the water-volt effect, its fabrication method, and its applications.

Abstract

The application discloses a self-powered flexible water content sensor based on water immersion effect and a preparation method and application thereof, and the sensor comprises a stretchable flexible substrate and a composite functional layer on the substrate, and the composite functional layer is provided with positive and negative electrodes and an encapsulation layer. The method comprises the following steps: step 1, preparing the stretchable flexible substrate on a rigid substrate; step 2, preparing the composite functional layer on the stretchable flexible substrate; step 3, preparing the positive and negative electrodes on the composite functional layer; step 4, preparing the encapsulation layer on the composite functional layer; and step 5, peeling off the stretchable flexible substrate. The sensor can be used for real-time monitoring of plant water information in the process of plant growth. The application can realize high-precision in-situ nondestructive sustainable monitoring of plant water information, and opens up a new direction for the development of intelligent agriculture.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sensors, in particular to a self-powered flexible moisture sensor based on water-induced effect and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of smart agriculture, it is necessary to realize real-time monitoring of crop physiological information, timely grasp the growth state of crops, and provide suitable conditions for the normal growth of crops according to the collected information, so as to realize high yield and high quality of crops, which is the key to reducing crop losses.

[0003] Water is an essential substance for plant growth and development, which directly affects the physiological activities of plants. In actual production process, in order to ensure that plants can carry out normal physiological activities, it is necessary to fully grasp the water information in the growth process of plants. However, the current common detection methods of plant water information have the limitations of hysteresis, low sensitivity, difficulty in realizing in-situ non-destructive sensing and inability to self-recharge. Therefore, it is urgent to obtain a new detection method to realize accurate, efficient, non-destructive, in-situ and continuous monitoring of plant water information, so as to accurately, timely and continuously grasp the water status in plant body, ensure the normal growth and development of plants, and meet the development and application requirements of modern agriculture.

[0004] In recent years, with the continuous development of sensing technology, material science and emerging energy technology, in-situ non-destructive continuous sensing technology has attracted widespread attention in the field of agriculture. In-situ non-destructive continuous sensing method does not need to pretreat plants, but only needs to design wearable sensing devices and continuous power supply systems for plants, so as to realize in-situ continuous monitoring of physiological signals of plants. This technology not only can accurately obtain physiological information of plants, but also will not cause damage to plants and can continuously monitor. Therefore, the preparation of self-powered flexible moisture sensor is one of the effective means to solve the problems existing in the traditional plant water information detection method, and is the key to promote the further development of smart agriculture. SUMMARY

[0005] The purpose of the present application is to provide a self-powered flexible moisture sensor based on water-induced effect and a preparation method and application thereof, so as to solve the problem that the water information during plant growth and development is difficult to be detected in real time and continuously.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0007] A self-powered flexible moisture sensor based on the water-voltaic effect includes a stretchable flexible substrate on which a flexible composite functional layer is fabricated. The composite functional layer is a blend of polyvinyl alcohol (PVA) and graphene oxide (GO). Positive and negative electrodes are fabricated on the composite functional layer. The composite functional layer allows water to permeate, and when water permeates the composite functional layer, a potential difference is generated between the positive and negative electrodes, thereby forming an electrical signal.

[0008] Furthermore, the stretchable flexible substrate is made of a stretchable polymer material.

[0009] Furthermore, the composite functional layer is made of a blend solution of polyvinyl alcohol solution and graphene oxide solution mixed in a mass ratio of 1:1 to 1:20.

[0010] Furthermore, the positive and negative electrodes are horizontally structured electrodes.

[0011] Furthermore, both the positive and negative electrodes are made of silver nanowire material.

[0012] Furthermore, a flexible encapsulation layer for encapsulating the entire device is also prepared on the positive and negative electrodes.

[0013] Furthermore, the encapsulation layer is made of polydimethylsiloxane, i.e., PDMS material.

[0014] A method for fabricating a self-powered flexible moisture sensor based on the water voltaic effect includes the following steps:

[0015] Step 1: Using a rigid substrate, a stretchable polymer solution is coated on the rigid substrate to prepare a stretchable flexible substrate in the form of a flexible thin film.

[0016] Step 2: After mixing PVA and GO solutions in a certain proportion, the mixture is coated onto the stretchable flexible substrate to obtain a composite functional layer in the form of a flexible thin film.

[0017] Step 3: Using silver nanowire stock solution, dilute the silver nanowire stock solution and coat it onto the composite functional layer to obtain positive and negative electrodes;

[0018] Step 4: Using PDMS stock solution, the PDMS stock solution and crosslinking agent are mixed in a certain proportion and then coated onto the composite functional layer and covered with positive and negative electrodes to obtain a flexible thin film encapsulation layer.

[0019] Step 5: Peel the stretchable flexible substrate from the rigid substrate to obtain a self-powered flexible moisture sensor based on the water-volt effect.

[0020] Furthermore, in step 1, the fabrication process of the stretchable flexible substrate is as follows:

[0021] A stretchable polymer material is selected, configured into a uniform bubble-free solution, and then spin-coated or blade-coated on a rigid substrate, followed by annealing treatment in a vacuum environment according to the properties of the selected stretchable polymer material, at a suitable annealing temperature and time, thereby coating and preparing a stretchable flexible substrate in the form of a flexible film on the rigid substrate.

[0022] Further, in step 1, the rigid substrate is cleaned before the stretchable flexible substrate is prepared.

[0023] Further, in step 2, the composite functional layer is prepared as follows:

[0024] A PVA solution with a concentration of 110 mg / ml and water as the solvent, and a GO solution with a concentration of 5 mg / ml and water as the solvent, are mixed uniformly in proportion, spin-coated or blade-coated on the stretchable flexible substrate, and then annealed in a vacuum environment at 100-135 DEG C for 89-91 min, thereby coating and preparing a composite functional layer in the form of a thin film on the substrate.

[0025] Further, in step 3, the silver nanowire stock solution is mixed with isopropanol to form a spraying solution for preparing the positive and negative electrodes.

[0026] Further, in step 3, the positive and negative electrodes are prepared as follows:

[0027] The substrate with the composite functional layer is preheated to 60-80 DEG C as a whole, a mask plate is then used to mask the composite functional layer and leave the positions of the positive and negative electrodes, the spraying solution is then sprayed onto the composite functional layer at the positions of the positive and negative electrodes, after the spraying is completed, annealing treatment is performed at 110-135 DEG C for 5-10 min, and finally the mask plate is removed, thereby coating and preparing the positive and negative electrodes on the composite functional layer.

[0028] Further, in step 4, the encapsulation layer is prepared as follows:

[0029] The PDMS stock solution is mixed with a crosslinking agent in a mass ratio of 10:1 to form a mixed solution, and the bubbles generated in the mixed solution are removed, the mixed solution is then spin-coated or blade-coated on the composite functional layer, and then annealing treatment is performed in a vacuum environment at 60-80 DEG C for at least 24 h, thereby coating and preparing an encapsulation layer in the form of a thin film on the composite functional layer.

[0030] The application of a self-powered flexible water sensor based on the water-induced effect in real-time monitoring of plant water information and judgment of plant growth state during plant growth.

[0031] Compared with the prior art, the application has the following advantages:

[0032] 1. The self-powered flexible moisture sensor based on the water vapor effect proposed in this invention does not require an external power supply system. It generates voltage spontaneously when there is water vapor in the air, thus saving energy and protecting the environment.

[0033] 2. The present invention proposes a self-powered flexible moisture sensor based on the water voltaic effect. The device has a simple structure, high adhesion to the plant surface, and will not cause damage to the plant.

[0034] 3. The present invention proposes a self-powered flexible moisture sensor based on the water voltaic effect. A composite functional layer film is prepared by mixing polyvinyl alcohol (PVA) and graphene oxide (GO) solution in a certain ratio (mass ratio 1:1~1:20). This not only enhances the hydrophilicity of the film and improves the device's high sensitivity to monitoring weak water molecules, enabling wide-range monitoring, but also improves the output performance of the self-powered device by changing the hydrogen ion concentration gradient difference and increasing the potential between the electrodes.

[0035] 4. The present invention proposes a self-powered flexible moisture sensor based on the water vapor effect, which converts the change in water vapor content released by plant transpiration into voltage and current signals, thereby enabling the monitoring of plant moisture information and thus achieving the goal of understanding the plant's growth and development status, promoting the rapid development of smart agriculture, improving crop yield and quality, ensuring economic benefits, and rationally irrigating and saving agricultural water. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the sensor structure according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the working principle of an embodiment of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] Example 1: Self-powered flexible moisture sensor structure based on the water voltaic effect.

[0040] like Figure 1 As shown, the sensor in this embodiment includes a stretchable flexible substrate 1 and a composite functional layer 2 fabricated on the stretchable flexible substrate 1. A positive electrode 3 and a negative electrode 4 are fabricated on the composite functional layer 2. Both the positive electrode 3 and the negative electrode 4 are horizontal electrodes. Furthermore, an encapsulation layer 5 covering the positive electrode 3 and the negative electrode 4 is also fabricated on the composite functional layer 2. The stretchable flexible substrate 1, the composite functional layer 2, and the encapsulation layer 5 are all in the form of flexible thin films.

[0041] In the sensor of the embodiment, the stretchable flexible substrate 1 is made of a stretchable polymer material. The stretchable polymer material should have good deformation ability, be able to conform to any curved surface, and have good chemical corrosion resistance. In the embodiment, the stretchable polymer material is polydimethylsiloxane (PDMS) or hydrogenated styrene-butadiene block copolymer (SEBS) or thermoplastic polyurethane elastomer (TPU). After the stretchable flexible substrate material is configured into a solution, it is prepared by spin coating or blade coating process.

[0042] In the sensor of the embodiment, the composite functional layer 2 is prepared by spin coating or blade coating process on the stretchable flexible substrate 1 after the polyvinyl alcohol solution (PVA solution) and graphene oxide solution (GO solution) are uniformly blended in a mass ratio of 1:1 to 1:20. The composite functional layer 2 has a rich channel structure and strong hydrophilicity. Even under weak water vapor conditions, it can adsorb water molecules, allowing water molecules to gradually penetrate into the deep area of the composite functional layer 2. Under the driving of the hydrogen ion concentration difference, free hydrogen ions move with water molecules, generating a potential difference between the positive and negative electrodes 3 and 4, outputting an electrical signal, and realizing water sensing and self-power supply.

[0043] In the sensor of the embodiment, the positive and negative electrodes 3 and 4 are respectively located on the left and right sides of the composite functional layer 2. In the sensor of the embodiment, silver nanowire (Ag NW) stock solution is uniformly mixed with isopropyl alcohol to form a spraying solution. Isopropyl alcohol is used as a solvent to dilute the silver nanowire stock solution and prevent the spraying gun from being blocked due to excessive concentration of the stock solution. The spraying solution is sprayed on the left and right sides of the composite functional layer 2 using a spraying process combined with a mask, thereby obtaining the positive and negative electrodes 3 and 4.

[0044] In the sensor of the embodiment, the encapsulation layer 5 is made of polydimethylsiloxane (PDMS) stock solution. The PDMS stock solution is uniformly mixed with a crosslinking agent to form a mixed solution, which is then spin coated or blade coated on the composite functional layer 2, thereby obtaining the encapsulation layer 5. The encapsulation layer 5 is used to improve the environmental stability of the sensor and prevent the electrodes from being affected by external environmental factors.

[0045] Embodiment two, a self-powered flexible moisture sensor preparation method based on water-induced effect.

[0046] The method of the embodiment includes the following steps:

[0047] Step 1: A rigid substrate is used, and a PDMS solution is used. The PDMS stock solution and the crosslinking agent are uniformly mixed in a mass ratio of 10:1 to form a mixed solution, and the bubbles generated in the mixed solution are removed. The prepared PDMS solution is coated on the rigid substrate, thereby obtaining a stretchable flexible substrate in the form of a flexible film.

[0048] In step 1, the size of the rigid substrate is 2.5 cm x 2.5 cm, the material is glass or silicon wafer, and the rigid substrate is cleaned and surface treated before the preparation of the stretchable flexible substrate. The cleaning process is as follows: the rigid substrate is sequentially ultrasonically cleaned in acetone, isopropyl alcohol and deionized water for 5-10 min, and then dried with nitrogen for standby. The surface treatment process is as follows: after plasma treatment for 5-10 min, octadecyl octyltrichlorosilane (OTS) is used for treatment for 20 min; when OTS is used for treatment, OTS and toluene are mixed in a clean petri dish at a volume ratio of 23 ul:10 ml, and then placed in the substrate to be treated, heated at 60°C for 20 min, and then the treated sample is washed with toluene and isopropyl alcohol, and dried with nitrogen for standby.

[0049] The preparation process of the stretchable flexible substrate is as follows:

[0050] The uniform bubble-free PDMS solution is spin-coated or blade-coated on the rigid substrate, and then annealed in a vacuum furnace at a temperature of 80°C for 24 h to obtain a stretchable flexible substrate in the form of a flexible film.

[0051] In step 2, the polyvinyl alcohol solution and the graphene oxide solution are blended in proportion, and then coated on the stretchable flexible substrate to obtain a composite functional layer in the form of a flexible film, and the specific process is as follows:

[0052] The PVA solution with a concentration of 110 mg / ml and water as the solvent, and the GO solution with a concentration of 5 mg / ml and water as the solvent are mixed uniformly at a mass ratio of 1:10, and then spin-coated or blade-coated on the stretchable flexible substrate, and then annealed in a vacuum box at a temperature of 100-135°C for 90 min, thereby coating and preparing a composite functional layer in the form of a thin film on the stretchable flexible substrate.

[0053] In step 3, the silver nanowire stock solution is diluted and coated on the composite functional layer to obtain the positive and negative electrodes, and the process is as follows:

[0054] First, the silver nanowire stock solution (5 mg / ml) is mixed with isopropyl alcohol at a volume ratio of 1:10 to form a spraying solution.

[0055] Then, the substrate with the composite functional layer is placed on a heating table and preheated to 80°C, then a mask plate is placed on the composite functional layer to leave the positive and negative electrode positions, then the spraying solution is sprayed onto the positive and negative electrode positions left on the composite functional layer, and after the spraying is completed, annealing treatment is carried out at a temperature of 115°C for 5 min to improve the conductivity, and finally the mask plate is removed, thereby coating and preparing the positive and negative electrodes on the composite functional layer.

[0056] Step 4, using PDMS stock solution, PDMS stock solution and crosslinking agent are mixed in proportion to prepare PDMS solution, then the PDMS solution is coated on the composite functional layer to cover the positive and negative electrodes to obtain a flexible thin film shaped encapsulation layer; the process is as follows:

[0057] The PDMS stock solution and the crosslinking agent are mixed in a mass ratio of 10:1 to form a mixed solution, and vacuum is applied to remove the air bubbles generated by stirring in the mixed solution. Then the mixed solution is spin-coated or blade-coated on the composite functional layer, and then annealed at 80°C in a vacuum environment for at least 24 hours, thereby coating and preparing a thin film shaped encapsulation layer on the composite functional layer.

[0058] Step 5, the rigid substrate is peeled off from the stretchable flexible substrate to obtain a self-powered flexible water sensor based on water evaporation effect.

[0059] As shown in Figure 2 When the self-powered flexible water sensor based on water evaporation effect prepared by the method of the embodiment is directly attached to the surface of a plant leaf, the PVA / GO composite functional layer film can adsorb water molecules, allowing water molecules to gradually penetrate into the deep area of the composite functional layer. Under the driving of the difference in hydrogen ion concentration, free hydrogen ions move with water molecules, a potential difference is generated between the electrodes, and an electrical signal is output, thereby realizing non-destructive in-situ sustainable monitoring of plant transpiration water information.

[0060] Example Three, a method for preparing a self-powered flexible water sensor based on water evaporation effect.

[0061] The method of the embodiment includes the following steps:

[0062] Step 1, a rigid substrate is used, and a SEEB solution is used, wherein the solvent of the SEEB solution is toluene, and the concentration is 80 mg / ml. The SEEB solution is coated on the rigid substrate, thereby preparing a stretchable flexible substrate in a flexible thin film shape.

[0063] In step 1, the size of the rigid substrate is 2.5 cm x 2.5 cm, and the material is glass or silicon wafer. After cleaning and surface treatment of the rigid substrate, the stretchable flexible substrate is prepared. The cleaning process and the surface treatment process are the same as in example two.

[0064] The preparation process of the stretchable flexible substrate is as follows:

[0065] SEEB powder is dissolved in toluene to form a SEEB solution with a concentration of 80 mg / ml. The SEEB solution is spin-coated or blade-coated on the rigid substrate, and then annealed in a vacuum furnace at a temperature of 120°C for 30 minutes to obtain a stretchable flexible substrate in a flexible thin film shape.

[0066] Step 2, after the polyvinyl alcohol solution and the graphene oxide solution are blended in proportion, the composite functional layer in the form of a flexible film is prepared on the stretchable flexible substrate, and the specific process is as follows:

[0067] The PVA solution with a concentration of 110 mg / ml and the solvent of water and the GO solution with a concentration of 5 mg / ml and the solvent of water are mixed uniformly in a mass ratio of 1:10, and then the PVA solution and the GO solution are spin-coated or blade-coated on the stretchable flexible substrate, and then annealed at 100-135 ℃ for 90 min in a vacuum box, so as to prepare the composite functional layer in the form of a film on the stretchable flexible substrate.

[0068] Step 3, the silver nanowire stock solution is diluted and coated on the composite functional layer to obtain the positive and negative electrodes, and the process is as follows:

[0069] First, the silver nanowire stock solution is mixed with isopropanol in a ratio of 1:10 to form a spraying solution.

[0070] Then, the substrate with the composite functional layer is placed on a heating table and preheated to 80 ℃, then a mask plate is covered on the composite functional layer to leave the positive and negative electrode positions, then the spraying solution is sprayed onto the positive and negative electrode positions left on the composite functional layer, and after the spraying is completed, annealing treatment is performed at 115 ℃ for 5 min to improve the conductivity, and finally the mask plate is removed, so as to prepare the positive and negative electrodes on the composite functional layer.

[0071] Step 4, the PDMS stock solution is mixed with the crosslinking agent in proportion and coated on the composite functional layer to cover the positive and negative electrodes to obtain the packaging layer in the form of a flexible film; the process is as follows:

[0072] The PDMS stock solution and the crosslinking agent are mixed and stirred uniformly in a mass ratio of 10:1 to form a mixed solution, and vacuum is applied to remove the air bubbles generated in the mixed solution due to stirring, and then the mixed solution is spin-coated or blade-coated on the composite functional layer, and then annealed at 80 ℃ for at least 24 h in a vacuum environment, so as to prepare the packaging layer in the form of a film on the composite functional layer.

[0073] Step 5, the stretchable flexible substrate is peeled off from the rigid substrate to obtain the self-powered flexible water sensor based on the water-induced effect.

[0074] When the self-powered flexible water vapor sensor based on water volatilization effect prepared in Example 2 is directly attached to the surface of a plant leaf, the PVA / GO composite functional layer film can adsorb water molecules, and the water molecules gradually penetrate into the deep area of the composite functional layer. Under the driving of the hydrogen ion concentration difference, the free hydrogen ions move with the water molecules, a potential difference is generated between the electrodes, an electrical signal is output, and the non-destructive in-situ sustainable monitoring of the water vapor information of plant transpiration can be realized.

[0075] Test example.

[0076] The performance test of the self-powered flexible water vapor sensor based on water volatilization effect prepared according to Example 2 is carried out according to the method disclosed in the prior art. The specific method is as follows: the voltage and current signals of the self-powered water vapor sensing device prepared above are collected by using a universal meter, different relative humidity (RH) environments are obtained by a bubbling method, and are corrected by a high-precision humidity sensor, and the relative humidity includes 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 95%.

[0077] The performance test of the self-powered flexible water vapor sensor based on water volatilization effect prepared according to Example 3 with SEBS as the stretchable substrate is carried out according to the method disclosed in the prior art. The specific method is as follows: the voltage and current signals of the self-powered water vapor sensing device prepared above are collected by using a universal meter, different relative humidity (RH) environments are obtained by a bubbling method, and are corrected by a high-precision humidity sensor, and the relative humidity includes 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 95%.

[0078] The embodiments described in the present application are only used to describe the preferred embodiments of the present application, and do not limit the concept and scope of the present application. Without departing from the design idea of the present application, various modifications and improvements of the technical solutions of the present application made by the engineering technicians in the field shall fall within the protection scope of the present application. The technical content of the present application claimed for protection has been entirely recorded in the claims.

Claims

1. A self-powered flexible moisture sensor based on the water-volt effect, characterized in that, The invention includes a stretchable flexible substrate on which a flexible composite functional layer is fabricated. The composite functional layer is a blend of polyvinyl alcohol (PVA) and graphene oxide (GO). Positive and negative electrodes are fabricated on the composite functional layer. The composite functional layer allows water to permeate, and when water permeates the composite functional layer, a potential difference is generated between the positive and negative electrodes, thereby forming an electrical signal. The stretchable flexible substrate is made of a stretchable polymer material; The composite functional layer is a blend of polyvinyl alcohol solution and graphene oxide solution mixed in a mass ratio of 1:1 to 1:20; The positive and negative electrodes are horizontal structure electrodes, both made of silver nanowire material; a flexible encapsulation layer for encapsulating the entire device is also prepared on the positive and negative electrodes, the encapsulation layer being made of polydimethylsiloxane, i.e., PDMS material.

2. A method for fabricating a self-powered flexible moisture sensor based on the water-volt effect as described in claim 1, characterized in that, Includes the following steps: Step 1: Using a rigid substrate, a stretchable polymer solution is coated on the rigid substrate to prepare a stretchable flexible substrate in the form of a flexible thin film. Step 2: After mixing PVA and GO solutions in a certain proportion, the mixture is coated onto the stretchable flexible substrate to obtain a composite functional layer in the form of a flexible thin film. Step 3: Using silver nanowire stock solution, dilute the silver nanowire stock solution and coat it onto the composite functional layer to obtain positive and negative electrodes; Step 4: Using PDMS stock solution, the PDMS stock solution and crosslinking agent are mixed in a certain proportion and then coated onto the composite functional layer and covered with positive and negative electrodes to obtain a flexible thin film encapsulation layer. Step 5: Peel the stretchable flexible substrate from the rigid substrate to obtain a self-powered flexible moisture sensor based on the water-volt effect.

3. The method for fabricating a self-powered flexible moisture sensor based on the water-volt effect according to claim 2, characterized in that, In step 1, the fabrication process of the stretchable flexible substrate is as follows: A stretchable polymer material is selected and prepared into a uniform, bubble-free solution. The solution is then spin-coated or scraped onto a rigid substrate. Subsequently, an appropriate annealing temperature and time are selected based on the properties of the selected stretchable polymer material, and the substrate is annealed in a vacuum environment. This process is used to coat a stretchable flexible substrate in the form of a flexible thin film onto a rigid substrate.

4. The method for fabricating a self-powered flexible moisture sensor based on the water-volt effect according to claim 2, characterized in that, The fabrication process of the composite functional layer in step 2 is as follows: A PVA solution with a concentration of 110 mg / ml and a water solvent, and a GO solution with a concentration of 5 mg / ml and a water solvent were mixed evenly in a certain proportion and then spin-coated or blade-coated onto a stretchable flexible substrate. The substrate was then annealed in a vacuum environment at 100~135 ℃ for 89~91 min to prepare a thin film-shaped composite functional layer on the substrate.

5. The method for fabricating a self-powered flexible moisture sensor based on the water-volt effect according to claim 2, characterized in that, In step 3, the silver nanowire stock solution is mixed evenly with isopropanol to form a spraying solution, which is used to prepare the positive and negative electrodes. The preparation process of the positive and negative electrodes in step 3 is as follows: The substrate with the composite functional layer is preheated to 60-80 ℃. Then, the positive and negative electrode positions are left on the composite functional layer by using a mask. Next, the spraying solution is sprayed onto the left positive and negative electrode positions on the composite functional layer. After spraying, the substrate is annealed at 110-135 ℃ for 5-10 min. Finally, the mask is removed, thus coating and preparing the positive and negative electrodes on the composite functional layer.

6. The method for fabricating a self-powered flexible moisture sensor based on the water-volt effect according to claim 2, characterized in that, The encapsulation layer fabrication process in step 4 is as follows: The PDMS stock solution and crosslinking agent are mixed evenly at a mass ratio of 10:1 to form a mixture, and the air bubbles generated in the mixture are removed. Then, the mixture is spin-coated or scraped onto the composite functional layer. Next, it is annealed in a vacuum environment at 60~80 °C for at least 24 h, thereby coating the composite functional layer to obtain a thin film-shaped encapsulation layer.

7. An application of the self-powered flexible moisture sensor based on the water voltaic effect as described in claim 1 in real-time monitoring of plant moisture information during plant growth and thus determining the plant growth status.

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