A silver nanowire antifreeze self-powered hydrogel flexible sensor and its preparation method and application

Abstract

This patent application provides a silver nanowire anti-freezing self-powered hydrogel flexible sensor, its preparation method and application. In the present invention, silver nanowires with a high aspect ratio are synthesized as conductive fillers, and hydrogen bonds are formed between the hydroxyl groups in butylene glycol (BD) and the water molecules in the hydrogel to endow the hydrogel with freezing resistance. This hydrogel sensor still has good tensile properties and sensing properties at -40°C. On the basis of this hydrogel flexible sensor, a self-powered flexible sensor with a simple structure is designed and prepared. The present invention overcomes the limitation of traditional anti-freezing hydrogel flexible sensors based on organic solvents. Compared with the prior art, the silver nanowire anti-freezing self-powered hydrogel flexible sensor prepared by the present invention has the characteristics of good anti-freezing property, good flexibility, excellent tensile properties and good working stability.

Description

Technical Field

[0001] The present invention belongs to the field of flexible sensing, and relates to a self-powered sensor, in particular to a silver nanowire anti-freezing self-powered hydrogel flexible sensor and its preparation method and application. Background Art

[0002] Conductive hydrogel is a three-dimensional water-containing material with conductive ability, and has excellent stretchability, compressibility, flexibility, and sensing properties, etc., which has received extensive attention from researchers. However, most hydrogels are not conductive and need to add conductive substances to achieve their conductive and sensing properties. Moreover, because the hydrogel contains water that freezes at low temperatures, the stretching and sensing properties of the conductive hydrogel decrease or even lose sharply at low temperatures.

[0003] Existing conductive fillers mainly include ionic conductive fillers and electronic conductive fillers. At low temperatures, the conductive ability of ionic conductive fillers will decrease sharply as the hydrogel freezes, while the influence of the conductive ability of electronic conductive fillers at low temperatures is smaller than that of ionic conductive fillers. As a one-dimensional electronic conductive filler, silver nanowires (AgNWs) have excellent electrical conductivity, thermal conductivity, anti-oxidation and corrosion resistance, and flexibility, etc. At the same time, compared with other forms of silver nanomaterials, silver nanowires can greatly reduce the consumption of silver materials.

[0004] In addition, existing anti-freezing conductive hydrogels mainly introduce organic solvents such as ethylene glycol or glycerol. Ethylene glycol or glycerol forms strong hydrogen bonds with water to destroy the formation of ice crystals at low temperatures, thereby endowing the conductive hydrogel with anti-freezing properties. However, the types of current organic anti-freezing solvents are limited, which limits the development of anti-freezing hydrogels.

[0005] Flexible sensors based on conductive hydrogels can detect skin physiological and motion signals in real time, improving health and prevention levels. At present, conductive hydrogel flexible sensors need to provide an additional power source to convert physiological and motion signals into electrical signals. With the multi-functionalization and complexity of the sensing network, the number of required batteries increases sharply and the power source needs to be replaced frequently, which poses new challenges to battery recycling and environmental protection.

[0006] The research group of Academician Zhonglin Wang first invented a new type of self-driven technology, triboelectric nanogenerator (TENG), in 2012, which uses the triboelectric effect to convert mechanical energy into electrical energy to drive conductive hydrogel flexible sensors without external power supply, so as to realize the monitoring of human physiology and motion. In summary, how to provide an anti-freezing, self-powered hydrogel flexible sensor without organic solvents is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention discloses a silver nanowire anti-freezing self-powered hydrogel flexible sensor and its preparation method and application.

[0008] It should be noted that in the present invention, by introducing butanediol (BD) rich in a large number of hydroxyl groups, hydrogen bonds are formed between the hydroxyl groups in butanediol BD and the water molecules in the hydrogel, endowing the hydrogel with anti-freezing performance, and the hydrogel sensor will not freeze even at -40°C. At the same time, using polyvinyl alcohol (PVA) as the first network and copolymerizing N-hydroxyethyl acrylamide (HEAA) and butanediol (BD) as the second network, the double-network structure design endows the hydrogel with good mechanical properties; and the addition of silver nanowires enables the hydrogel to maintain good conductivity and sensing performance at low temperatures.

[0009] Based on this hydrogel flexible sensor, the present invention designs and prepares a self-powered flexible sensor with a simple structure, solving the limitation that flexible sensors require an external power source.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] The first object of the present invention is to provide a silver nanowire anti-freezing self-powered hydrogel flexible sensor, which is obtained by pasting a conductive copper sheet on one side of the hydrogel and then wrapping the hydrogel with silicone rubber; wherein,

[0012] the hydrogel is a PVA / p(HEAA-co-BD) / AgNWs hydrogel.

[0013] The second object of the present invention is to provide a preparation method of the silver nanowire anti-freezing self-powered hydrogel flexible sensor as described above, and the method specifically includes the following steps:

[0014] 1) Preparation of silver nanowires:

[0015] Slowly add silver nitrate solution to an ethylene glycol solution dissolved with polyvinylpyrrolidone (PVP) and copper chloride, stir evenly, raise the temperature for reaction, and obtain silver nanowires (AgNWs) through centrifugation and washing;

[0016] 2) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel:

[0017] Dissolve N-hydroxyethyl acrylamide (HEAA), polyvinyl alcohol (PVA), butanediol (BD), N,N-methylenebisacrylamide, photoinitiator I2959, and the silver nanowires (AgNWs) prepared in step 1) in deionized water, stir and mix to obtain a prepolymer solution;

[0018] Inject the prepolymer solution into a glass mold and obtain a PVA / p(HEAA-co-BD) / AgNWs hydrogel through ultraviolet irradiation;

[0019] 3) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel self-powered sensor:

[0020] Cut the hydrogel obtained in step 2), attach a conductive copper sheet to one side of the cut hydrogel, and wrap the hydrogel with silicone rubber to prepare a hydrogel self-powered sensor.

[0021] Optionally, in step 1), the mass ratio of silver nitrate (AgNO3), polyvinylpyrrolidone (PVP), and copper dichloride dihydrate (CuCl2·2H2O) is 0.68:0.888:0.001364.

[0022] Furthermore, the reaction temperature in step 1) is 140 °C and the reaction time is 3 h.

[0023] Optionally, in step 2), the PVA / p(HEAA-co-BD) / AgNWs hydrogel is prepared from the following substances, by mass percentage:

[0024] N-hydroxyethyl acrylamide (HEAA) 30%-50%, polyvinyl alcohol (PVA) 4%-8%, butanediol (BD) 6%-10%, N,N-methylenebisacrylamide 0.1%-0.2%, photoinitiator (I2959) 1%-2%, silver nanowires (AgNWs) 0.2%-0.6%, deionized water 29.2%-58.7%.

[0025] Preferably, N-hydroxyethyl acrylamide (HEAA) 50%, polyvinyl alcohol (PVA) 8%, butanediol (BD) 10%, N,N-methylenebisacrylamide 0.2%, photoinitiator (I2959) 1%, silver nanowires (AgNWs) 0.4%, deionized water 30.4%.

[0026] It should be noted that under ultraviolet light irradiation, the photoinitiator initiates the free radical polymerization reaction of the monomers to form a hydrogel. This preparation method uses a one-pot operation and has the characteristics of simple operation.

[0027] Optionally, in step 2), the stirring temperature of the prepolymer solution is 80 °C - 95 °C, the stirring time is 30 min - 60 min, and the stirring rate is 400 - 700 rpm.

[0028] Optionally, in step 2), the wavelength of the ultraviolet light irradiation is 365 nm and the irradiation time is 2 - 5 h.

[0029] Preferably, the thickness range of the glass mold is 1 mm - 2 mm, and a layer of PET film is provided between the contact surface of the glass mold and the prepolymer solution.

[0030] Optionally, in step 3), the hydrogel is cut into a size of 20 mm × 30 mm.

[0031] The third object of the present invention is to provide an application of a silver nanowire antifreeze self-powered hydrogel flexible sensor in the field of flexible wearable devices.

[0032] Furthermore, the silver nanowire antifreeze self-powered hydrogel flexible sensor is used for physiological, motion, and health monitoring.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The conductive hydrogel disclosed in the present invention adopts a double-network structure design, with polyvinyl alcohol (PVA) as the first network and the copolymerization of N-hydroxyethyl acrylamide (HEAA) and butanediol (BD) as the second network. The double-network structure design endows the hydrogel with good mechanical properties.

[0035] (2) The friction layer disclosed in the present invention completely wraps the electrode layer, avoiding the exposure and wear of the electrode layer, and ensuring the long-term working stability of the antifreeze self-powered hydrogel sensor.

[0036] (3) The electrode layer of the hydrogel sensor disclosed in the present invention is composed of PVA / p(HEAA-co-BD) / AgNWs hydrogel. Due to the introduction of butanediol (BD), the hydrogel copolymerizes with N-hydroxyethyl acrylamide. The hydroxyl groups in BD form hydrogen bonds with the water molecules in the hydrogel, endowing the hydrogel with freezing resistance. This hydrogel sensor still does not freeze at -40°C.

[0037] (4) The silver nanowires (AgNWs) synthesized in the present invention have a high aspect ratio. Using fewer high-aspect-ratio silver nanowires can still endow the hydrogel with good conductive and sensing properties. Moreover, as a conductive filler, silver nanowires can still play a conductive role at low temperatures, overcoming the technical defect that ionic conductive hydrogels are prone to freezing and losing their conductive ability at low temperatures.

[0038] (5) The electrode layer of the hydrogel sensor disclosed in the present invention transmits electrical energy into the circuit through a conductive copper sheet, improving the charge collection ability of the antifreeze hydrogel flexible sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0040] Figure 1Schematic diagram of the self-powered flexible sensor of the present invention.

[0041] Figure 2 Schematic diagram of the power generation principle of the self-powered flexible sensor of the present invention.

[0042] Figure 3 Physical diagram of the self-powered flexible sensor of the present invention.

[0043] Figure 4 SEM image of silver nanowires in Example 1 of the present invention.

[0044] Figure 5 Tensile property test diagram of PVA / p(HEAA-co-BD) / AgNWs hydrogel in Example 1 of the present invention at room temperature.

[0045] Figure 6 Tensile property test diagram of PVA / p(HEAA-co-BD) / AgNWs hydrogel in Example 1 of the present invention at -40°C.

[0046] Figure 7 Schematic diagram of the voltage output of the self-powered flexible sensor in Example 1 of the present invention.

[0047] Figure 8 Schematic diagram of the current output of the self-powered flexible sensor in Example 1 of the present invention.

[0048] Figure 9 Schematic diagram of the charge output of the self-powered flexible sensor in Example 1 of the present invention.

[0049] Figure 10 Durability test of the self-powered flexible sensor in Example 1 of the present invention for 2000 cycles.

[0050] Figure 11 Schematic diagram of the voltage output for monitoring knee bending at room temperature of the self-powered flexible sensor in Example 4 of the present invention.

[0051] Figure 12 Schematic diagram of the voltage output for monitoring finger bending at -40°C of the self-powered flexible sensor in Example 5 of the present invention.

[0052] Figure 13 The self-powered flexible sensor in Example 1 of the present invention lights 45 small light bulbs.

[0053] In the figure, 1 is the friction layer (silicone rubber (-Ecoflex)), 2 is the electrode layer (PVA / p(HEAA-co-BD) / AgNWs hydrogel), 3 is the base layer (polyurethane (PU)), 4 is the copper sheet, 5 is the negative charge, and 6 is the positive charge. Detailed implementation manners

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] The special term "embodiment" used here, any embodiment described as "exemplary" does not have to be construed as superior or better than other embodiments. For the performance index tests in the embodiments of this application, unless otherwise specified, conventional test methods in the art are adopted. It should be understood that the terms described in this application are only for describing specific embodiments and are not used to limit the content disclosed in this application.

[0056] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the technical field to which this application belongs; the test methods and technical means not specifically noted in this application refer to the experimental methods and technical means commonly adopted by those of ordinary skill in the art.

[0057] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "inside", "upper", "lower", "rise", "fall", "vertical", "surface", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention.

[0058] To better illustrate the content of this application, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that this application can also be implemented without some specific details. In the embodiments, some methods, means, instruments, devices, etc. well-known to those skilled in the art are not described in detail in order to highlight the gist of this application.

[0059] On the premise of no conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the obtained technical solutions belong to the content disclosed in the embodiments of this application.

[0060] The present invention discloses a silver nanowire antifreeze self-powered hydrogel flexible sensor and a preparation method thereof.

[0061] Figure 1 In 1 is the friction layer, and 2 is the electrode layer. The electrode layer 2 is composed of a PVA / p(HEAA-co-BD) / AgNWs hydrogel, where PVA is polyvinyl alcohol, HEAA is N-hydroxyethyl acrylamide, BD is butanediol, and AgNWs is silver nanowires.

[0062] Figure 2 Schematic diagram of power generation for a self-powered flexible sensor.

[0063] Step ①: When the friction layer 1 contacts the base layer 3, due to the different abilities of the two materials to acquire electrons in the triboelectrification phenomenon, equal amounts of opposite charges will be generated at the interface.

[0064] Step ②: Under the action of an external force, the friction layer 1 and the base layer 3 gradually separate, and free electrons will migrate from the ground to the hydrogel electrode 2, forming a potential difference between the electrode and the ground.

[0065] Step ③: When the distance between the friction layer 1 and the base layer 3 is large, the open-circuit voltage reaches saturation.

[0066] Step ④: Continuing under the action of an external force, the materials of the friction layer 1 and the base layer 3 gradually come into contact from the separated state, and free electrons migrate from the hydrogel electrode 2 to the ground, forming a potential difference between the electrode and the ground. This cycle is repeated to form an alternating voltage.

[0067] The electrode layer 2 is composed of PVA / p(HEAA-co-BD) / AgNWs hydrogel. The hydrogel copolymerizes with N-hydroxyethyl acrylamide due to the introduction of butanediol (BD). The hydroxyl groups in BD form hydrogen bonds with the water molecules in the hydrogel, endowing the hydrogel with freezing resistance. This hydrogel sensor will still not freeze at -40°C; and the silver nanowires (AgNWs) in the hydrogel act as conductive fillers and can still play a conductive role at low temperatures. While ionic conductive hydrogels are prone to freezing at low temperatures and lose their conductive ability.

[0068] To better understand the present invention, the following embodiments are used to further specifically elaborate the present invention, but it should not be construed as a limitation of the present invention. For some non-essential improvements and adjustments made by those skilled in the art based on the above invention content, they are also considered to fall within the protection scope of the present invention.

[0069] Example 1

[0070] 1) The preparation method of silver nanowires includes the following steps:

[0071] Weigh 0.888 g of polyvinylpyrrolidone (PVP) and dissolve it in 40 mL of ethylene glycol solution. Stir at 90 °C to prepare solution S1; weigh 0.0341 g of CuCl₂·2H₂O and dissolve it in ethylene glycol solution to prepare 50 mL of solution S2; weigh 2 mL of solution S2 and dissolve it in solution S1 to prepare solution S3; weigh 0.68 g of silver nitrate and dissolve it in 40 mL of ethylene glycol solution, stir at room temperature to dissolve and prepare solution S4; slowly add solution S4 to solution S3, stir evenly at room temperature to obtain solution S5; transfer solution S5 to a 100 mL reaction kettle, place it in an oven at 140 °C for reaction for 3 h, then take it out for centrifugation, wash it with ethanol by centrifugation 3 times, and wash it with deionized water by centrifugation 2 times to obtain silver nanowires (AgNWs).

[0072] 2) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel:

[0073] Dissolve N-hydroxyethyl acrylamide (2.5 g, 50 wt%), polyvinyl alcohol (0.4 g, 8 wt%), butanediol (0.5 g, 10 wt%), N,N-methylenebisacrylamide (0.01 g, 0.2%), photoinitiator I2959 (0.05 g, 1 wt%), and silver nanowires (0.02 g, 0.4 wt%) in deionized water (1.52 g, 30.4 wt%), stir at 95 °C and 700 rpm for 30 min to obtain solution S6; transfer solution S6 to a 1 mm thick glass template and irradiate it with 365 nm ultraviolet light for 3 h to obtain PVA / p(HEAA-co-BD) / AgNWs hydrogel S7.

[0074] 3) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel self-powered sensor:

[0075] Cut the hydrogel S7 into a size of 20 mm × 30 mm, stick a conductive copper sheet on one side of the hydrogel S7, and wrap the hydrogel S7 with silicone rubber to prepare the hydrogel self-powered sensor S8;

[0076] Frictionally power the prepared hydrogel self-powered sensor S8 with polyurethane (PU), connect the wire of the hydrogel self-powered sensor S8 to an external circuit, and ground the other end of the external circuit, and further detect the output performance of the prepared hydrogel self-powered sensor.

[0077] Example 2

[0078] 1) Preparation method of silver nanowires: Refer to Example 1.

[0079] 2) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel:

[0080] Dissolve N - hydroxyethyl acrylamide (1.5 g, 30 wt%), polyvinyl alcohol (0.2 g, 4 wt%), butanediol (0.3 g, 6 wt%), N,N - methylene bisacrylamide (0.005 g, 0.1%), photoinitiator I2959 (0.05 g, 1 wt%), and silver nanowires (0.01 g, 0.2 wt%) in deionized water (2.935 g, 58.7 wt%). Stir at a temperature of 80 °C and a stirring speed of 400 rpm for 30 min to obtain solution S6. Transfer solution S6 to a 2 - mm - thick glass template and irradiate with 365 - nm ultraviolet light for 2 h to obtain the PVA / p(HEAA - co - BD) / AgNWs hydrogel S7.

[0081] 3) Preparation method of the PVA / p(HEAA - co - BD) / AgNWs hydrogel self - powered sensor: Refer to Example 1.

[0082] Example 3

[0083] 1) Preparation method of silver nanoparticles: Refer to Example 1.

[0084] 2) Preparation of the PVA / p(HEAA - co - BD) / AgNWs hydrogel:

[0085] Dissolve N - hydroxyethyl acrylamide (2.5 g, 50 wt%), polyvinyl alcohol (0.4 g, 8 wt%), butanediol (0.5 g, 10 wt%), N,N - methylene bisacrylamide (0.01 g, 0.2%), photoinitiator I2959 (0.05 g, 1 wt%), and silver nanowires (0.03 g, 0.6 wt%) in deionized water (1.51 g, 30.2 wt%). Stir at a temperature of 95 °C and a stirring speed of 700 rpm for 60 min to obtain solution S6. Transfer solution S6 to a 1 - mm - thick glass template and irradiate with 365 - nm ultraviolet light for 5 h to obtain the PVA / p(HEAA - co - BD) / AgNWs hydrogel S7.

[0086] 3) Preparation method of the PVA / p(HEAA - co - BD) / AgNWs hydrogel self - powered sensor: Refer to Example 1.

[0087] Example 4

[0088] The difference from Example 1 is that the hydrogel self - powered sensor S8 is attached to the skin for triboelectric power generation to self - poweredly monitor human motion.

[0089] Example 5

[0090] The difference from Example 1 is that the hydrogel self - powered sensor S8 is attached to the skin for triboelectric power generation to self - poweredly monitor human motion at - 40 °C.

[0091] The present invention synthesizes silver nanowires with a high aspect ratio by the polyol method, and then dissolves N-hydroxyethyl acrylamide, polyvinyl alcohol, butanediol, N,N-methylenebisacrylamide, a photoinitiator, and silver nanowires in deionized water, mixes them according to a certain ratio, and prepares an antifreeze hydrogel by photopolymerization. An antifreeze self-powered hydrogel flexible sensor is prepared based on this antifreeze hydrogel.

[0092] The results of the examples show that the silver nanowires prepared by the present invention based on the optimized components by the polyol method have a high aspect ratio. Figure 4 It shows that the diameter of the silver nanowires is 50 nm, the length reaches 17 μm, and the aspect ratio reaches 340. The antifreeze hydrogel synthesized by the present invention has excellent tensile properties and good flexibility, and still has good tensile properties and flexibility at -40 °C. Figure 5 It shows that the tensile stress of the prepared hydrogel reaches 1.42 MPa and the tensile strain reaches 783% at room temperature. Figure 6 It shows that the tensile stress of the prepared hydrogel is 2.67 MPa and the tensile strain is 559% at -40 °C. Figure 7 It shows that the open-circuit voltage (Voc) of the silver nanowire antifreeze self-powered hydrogel flexible sensor prepared based on this hydrogel can reach 170 V, and still maintains the initial open-circuit voltage after 2000 cycles ( Figure 10 ), indicating good stability. Figure 11 It shows that the silver nanowire antifreeze self-powered hydrogel flexible sensor can monitor human movement without an external power supply at room temperature, and can still self-power to monitor human movement at -40 °C ( Figure 12 ). Figure 13 It shows that the silver nanowire antifreeze self-powered hydrogel flexible sensor can light up 45 small light bulbs through self-power.

[0093] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a silver nanowire antifreeze self-powered hydrogel flexible sensor, characterized in that: The method specifically comprises the following steps: 1) Preparation of silver nanowires: Slowly add the silver nitrate solution into the ethylene glycol solution containing polyvinyl pyrrolidone and cupric chloride dihydrate, stir evenly, heat to react, centrifuge and wash to obtain silver nanowires AgNWs; 2) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel: Dissolving N-hydroxyethyl acrylamide HEAA, polyvinyl alcohol PVA, butylene glycol BD, N,N-methylene acrylamide, photoinitiator I2959, and the silver nanowires AgNWs prepared in step 1) in deionized water, and stirring and mixing to obtain a prepolymer solution; injecting the prepolymer solution into a glass mold, and irradiating it with ultraviolet light to obtain a PVA / p(HEAA-co-BD) / AgNWs hydrogel; The PVA / p(HEAA-co-BD) / AgNWs hydrogel is prepared from the following substances, calculated by mass percentage: N-hydroxyethyl acrylamide HEAA 30%-50%, polyvinyl alcohol PVA 4%-8%, butene glycol BD 6%-10%, N,N-methylene acrylamide 0.1%-0.2%, photoinitiator I2959 1%-2%, silver nanowires AgNWs 0.2%-0.6%, deionized water 29.2%-58.7%; 3) Preparation of PVA / p(HEAA-co-BD) / AgNWs hydrogel self-powered sensor: The hydrogel obtained in step 2) is cut, a conductive copper sheet is attached to one side of the cut hydrogel, and the hydrogel is wrapped with silicone rubber to prepare a hydrogel self-powered sensor.

2. The method for preparing the silver nanowire antifreeze self-powered hydrogel flexible sensor according to claim 1, characterized in that: In the step 1), the mass ratio of silver nitrate, polyvinyl pyrrolidone and cupric chloride dihydrate is 0.68:0.888:0.001364.

3. The method for preparing the silver nanowire antifreeze self-powered hydrogel flexible sensor according to claim 1 or 2, characterized in that: The reaction temperature in step 1) is 140° C. and the reaction time is 3 h.

4. The method for preparing the silver nanowire antifreeze self-powered hydrogel flexible sensor according to claim 1, characterized in that: In the step 2), the stirring temperature of the prepolymer liquid is 80° C.-95° C., the stirring time is 30 min-60 min, and the stirring speed is 400-700 rpm.

5. The method for preparing the silver nanowire antifreeze self-powered hydrogel flexible sensor according to claim 1, characterized in that: In the step 2), the wavelength of ultraviolet light irradiation is 365 nm, and the irradiation time is 2-5 h.

6. The method for preparing the silver nanowire antifreeze self-powered hydrogel flexible sensor according to claim 1, characterized in that: In the step 3), the hydrogel is cut into a size of 20 mm×30 mm.

7. An application of the silver nanowire antifreeze self-powered hydrogel flexible sensor prepared by the method as claimed in claim 1 in the field of flexible wearable equipment.

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