A temperature-sensitive flexible sensor and a preparation method thereof

Abstract

The application discloses a temperature-sensitive flexible sensor and a preparation method thereof, and belongs to the field of composite materials. The structure of the sensor is composed of a flexible base layer and a temperature-sensitive conductive layer, the temperature-sensitive conductive layer adopts a composite temperature-sensitive conductive material formed by MXene material and nano-silver material in a certain proportion, the flexible base layer adopts a mixed material of one or more of polyimide, polyethylene terephthalate and polyethylene naphthalate dihydric glycol ester (PEN) in any ratio, and the sensor is obtained by 3D printing the composite temperature-sensitive conductive material on the flexible base layer to form the temperature-sensitive conductive layer. The flexible base mainly adopted by the application is non-toxic polyimide, has good temperature resistance and mechanical properties, and can meet the requirements of various measurement sites; the temperature-sensitive conductive layer has good conductive performance and stability, and has a wide temperature test range.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to a temperature-sensitive flexible sensor, its preparation method, and its practical application. Background Technology

[0002] In recent years, flexible sensors have played an indispensable role in the information age, converting external physical or environmental changes into electrical signals and serving as a link between the natural environment and daily life. Because the conductivity of conductive polymers changes significantly under the influence of factors such as concentration, external temperature, and gas environment, the conductivity of conductive polymers is widely used in flexible piezoresistive strain sensors. Compared to traditional pressure sensors based on metallic materials, flexible piezoresistive strain sensors have advantages such as stretchability, wearability, high strain range, and reversibility. Furthermore, their synthesis process is simple and convenient, and can be achieved through chemical or electrochemical processes. Therefore, various novel devices using flexible piezoresistive strain sensors are increasingly being applied in fields such as electronic skin smart devices and healthcare.

[0003] 3D printing (3DP), a type of rapid prototyping technology also known as additive manufacturing, is a technique that uses digital model files as a basis and employs powdered metals or plastics and other bondable materials to construct objects layer by layer. 3D printing is typically achieved using digital material printers and has gained widespread attention in recent years due to its environmentally friendly advantages. It is commonly used in mold making and industrial design to create models, and is increasingly being used for the direct manufacturing of some products; parts printed using this technology already exist. This technology has applications in jewelry, footwear, industrial design, architecture, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, geographic information systems, civil engineering, firearms, and other fields. Summary of the Invention

[0004] The purpose of this invention is to provide a temperature-sensitive flexible sensor and its preparation method. This flexible sensor overcomes the shortcomings of traditional temperature sensors in terms of poor mechanical properties and has good conductivity and stability.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A temperature-sensitive flexible sensor is disclosed, comprising a flexible substrate layer and a temperature-sensitive conductive layer. The temperature-sensitive conductive layer is a composite temperature-sensitive conductive material formed by MXene and nano-silver in a certain proportion. The flexible substrate layer is a mixture of one or more of polyimide, polyethylene terephthalate, and polyethylene naphthalate (PEN) in any proportion. The sensor is obtained by 3D printing the composite temperature-sensitive conductive material onto the flexible substrate layer to form the temperature-sensitive conductive layer.

[0006] This invention also provides a method for preparing the above-mentioned temperature-sensitive flexible sensor, comprising: (1) Preparation of Mxene material: LiF powder was added to HCl solution and stirred at room temperature. Then Ti3AlC2 powder was added to the above solution in three portions. After water bath, dilution, centrifugation, filtration, washing and drying, Mxene material was obtained. (2) Preparation of silver nanomaterials: Prepare silver ammonia solution, add polyvinylpyrrolidone to it, stir to obtain solution A; then add anhydrous ethanol solution containing reducing agent to solution A, and react to obtain silver nanomaterial solution; (3) Preparation of conductive ink for M-Ag composite material: Take ethanol solution, MXene material and nano silver solution to prepare conductive filler ethanol dispersion; then take glycerol, deionized water and a certain volume of binder to prepare mixed solvent, and then mix conductive filler ethanol dispersion and mixed solvent to obtain M-Ag composite conductive ink. (4) Sensor fabrication: Add the M-Ag composite conductive ink obtained in step (3) to a 3D printer and 3D print it on a flexible substrate to obtain the sensor.

[0007] Furthermore, in step (1), the molar mass of LiF is 0.04–0.1 mol, the molar mass of HCl solution is 0.18 mol, and the molar mass of Ti3AlC2 is 0.01 mol.

[0008] Further, in step (1), the stirring time is 10 min, the water bath temperature is 45℃, the water bath reaction is 24 h, and after the reaction is completed, it is diluted with 10 times the volume of distilled water and centrifuged until the supernatant pH < 6.

[0009] Further, in step (2), the silver ammonia solution is prepared by dissolving 0.01 mol of silver nitrate in 100 mL of anhydrous ethanol under light-protected conditions to prepare a 0.1 mol / L silver nitrate ethanol solution, and then slowly adding ammonia water to prepare a silver ammonia solution, adjusting the pH value to 9.

[0010] Further, in step (2), the molar mass of the polyvinylpyrrolidone is 0 to 0.05 mol, and after the polyvinylpyrrolidone is added, it is stirred in a water bath at 60°C for 30 min.

[0011] Further, in step (2), the reducing agent is one or a mixture of glucose, hydrazine hydrate, sodium borohydride, and formaldehyde.

[0012] Preferably, the reducing agent is glucose. 0.02 mol of glucose is dissolved completely in 20 mL of anhydrous ethanol and then added dropwise to solution A. The solution is reacted in a water bath at 60°C for 1 h to obtain a nano-silver solution.

[0013] Further, in step (3), the mass-to-volume ratio of the MXene material, the nano-silver solution, and the ethanol solution is (0-0.04 g):(0-8 mL):2 mL.

[0014] Further, in step (3), the volume ratio of glycerol, deionized water and binder is 4 mL: 2 mL: (0-4 mL).

[0015] Further, in step (3), the binder is one or more of waterborne polyurethane / polyacrylate, acrylic resin, and polyurethane.

[0016] In summary, due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. This invention adds nano-silver particles to the conductive filler to avoid the accumulation between MXene materials, thereby enabling the conductive ink to be better and more uniformly dispersed on the flexible substrate; 2. The self-assembled M-Ag composite conductive ink of this invention is a nanocomposite material with temperature-sensitive properties, combining the conductivity of MXene material and nano-silver, and enhancing the stability of the temperature-sensitive material; 3. This invention utilizes MXene material, which has excellent heat resistance, to expand the temperature testing range of the flexible sensor and broaden its application areas; 4. The flexible substrate used in this invention is mainly non-toxic polyimide, which has good temperature resistance and mechanical properties, and can meet the needs of various measurement sites; 5. The temperature-sensitive flexible sensor of the present invention overcomes the shortcomings of poor mechanical properties of traditional temperature sensors; it also has good electrical conductivity. Attached Figure Description

[0017] Figure 1 This is a graph showing the resistance of a temperature-sensitive flexible sensor according to an embodiment of the present invention as a function of temperature. Figure 2 This is a graph showing the resistivity of a temperature-sensitive flexible sensor according to an embodiment of the present invention as a function of temperature. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example 1

[0019] First, 0.04 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0020] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.02 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0021] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0022] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a temperature-sensitive flexible sensor.

[0023] Please see the appendix Figure 1 and 2 As shown, the resistance and resistivity of the temperature-sensitive flexible sensor prepared in this embodiment gradually increase with increasing temperature. Example 2

[0024] First, 0.06 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0025] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.02 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0026] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0027] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 3

[0028] First, 0.08 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0029] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.02 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0030] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0031] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 4

[0032] First, 0.1 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0033] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.02 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0034] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0035] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 5

[0036] First, 0.08 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0037] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, and the pH was adjusted to 9. 0.01 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0038] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0039] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 6

[0040] First, 0.08 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0041] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.03 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0042] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0043] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 7

[0044] First, 0.08 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0045] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.04 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0046] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0047] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 8

[0048] First, 0.08 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0049] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, and the pH was adjusted to 9. 0.05 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0050] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0051] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 9

[0052] First, 0.08 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0053] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.02 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0054] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.02 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 2 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0055] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor. Example 10

[0056] First, 0.04 mol of LiF powder was added to 20 ml of a solution containing 0.18 mol of HCl. After stirring at room temperature for 10 min, 0.01 mol of Ti3AlC2 powder was added to the solution in three portions over 30 min. Then, the solution was heated to 45 °C in a water bath and reacted for 24 h. After the reaction was completed, the solution was diluted with 10 times its volume of distilled water, centrifuged until the pH of the supernatant was <6, filtered, washed, and dried to obtain the multilayer Mxene material.

[0057] Subsequently, under light-protected conditions, 0.01 mol of silver nitrate was dissolved in 100 mL of anhydrous ethanol, and then ammonia was slowly added to prepare a silver ammonia solution, adjusting the pH to 9. 0.02 mol of polyvinylpyrrolidone (PVP) was added to the above silver ammonia solution, and the mixture was stirred in a 60°C water bath for 30 min to obtain solution A. 0.02 mol of glucose was added to 20 mL of anhydrous ethanol, and after complete dissolution, it was added dropwise to solution A. The mixture was reacted in a 60°C water bath for 1 h to obtain a brownish-green solution, which is the prepared nano-silver solution.

[0058] Next, 4 mL of nano silver solution and 2 mL of anhydrous ethanol solution were measured, and 0.04 g of MXene material was weighed and added to the above mixture to obtain a conductive filler ethanol dispersion; 4 mL of glycerol and 2 mL of deionized water and 4 mL of polyurethane / polyacrylate solution were measured and added to the conductive filler ethanol dispersion to obtain conductive ink.

[0059] Finally, the M-Ag composite conductive ink prepared above is added to a 3D printer and printed using polyimide (PI) as a flexible substrate to obtain a flexible temperature sensor.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating a temperature-sensitive flexible sensor, characterized in that: The aforementioned temperature-sensitive flexible sensor comprises a flexible substrate layer and a temperature-sensitive conductive layer. The temperature-sensitive conductive layer is a composite temperature-sensitive conductive material formed by MXene and nano-silver materials in a certain proportion. The flexible substrate layer is a mixture of one or more of polyimide, polyethylene terephthalate, and polyethylene dinaphthalate (PEN) in any proportion. The specific preparation steps are as follows: (1) Preparation of Mxene material: LiF powder was added to HCl solution and stirred at room temperature. Then Ti3AlC2 powder was added to the above solution in three portions. After water bath, dilution, centrifugation, filtration, washing and drying, Mxene material was obtained. (2) Preparation of silver nanomaterials: Prepare silver ammonia solution, add polyvinylpyrrolidone to it, stir to obtain solution A; then add anhydrous ethanol solution containing reducing agent to solution A, and react to obtain silver nanomaterial solution; (3) Preparation of M-Ag composite conductive ink: Take ethanol solution, MXene material and nano silver solution to prepare conductive filler ethanol dispersion, wherein the amount of MXene material is 0.04g, the amount of nano silver solution is 4mL and the amount of ethanol solution is 2mL; then take glycerol, deionized water and a certain volume of binder to prepare mixed solvent, and then mix the conductive filler ethanol dispersion and mixed solvent to obtain M-Ag composite conductive ink; (4) Sensor fabrication: Add the M-Ag composite conductive ink obtained in step (3) to a 3D printer and 3D print it on a flexible substrate to obtain the sensor.

2. The method for fabricating a temperature-sensitive flexible sensor according to claim 1, characterized in that: In step (1), the molar mass of LiF is 0.04-0.1 mol, the molar mass of HCl solution is 0.18 mol, and the molar mass of Ti3AlC2 is 0.01 mol.

3. The method for fabricating a temperature-sensitive flexible sensor according to claim 2, characterized in that: In step (1), the stirring time is 10 min, the water bath temperature is 45℃, and the water bath reaction is 24 h. After the reaction is completed, it is diluted with 10 times the volume of distilled water and centrifuged until the pH of the supernatant is <6.

4. The method for fabricating a temperature-sensitive flexible sensor according to claim 3, characterized in that: In step (2), the silver ammonia solution is prepared by dissolving 0.01 mol of silver nitrate in 100 mL of anhydrous ethanol under light-protected conditions to prepare a 0.1 mol / L silver nitrate ethanol solution, and then slowly adding ammonia water to prepare the silver ammonia solution and adjusting the pH value to 9.

5. The method for fabricating a temperature-sensitive flexible sensor according to claim 4, characterized in that: In step (2), the molar mass of the polyvinylpyrrolidone is 0 to 0.05 mol, and after the polyvinylpyrrolidone is added, it is stirred in a water bath at 60°C for 30 min.

6. The method for fabricating a temperature-sensitive flexible sensor according to claim 5, characterized in that: In step (2), the reducing agent is one or a mixture of glucose, hydrazine hydrate, sodium borohydride, and formaldehyde.

7. The method for fabricating a temperature-sensitive flexible sensor according to claim 6, characterized in that: The reducing agent is glucose. 0.02 mol of glucose is dissolved completely in 20 mL of anhydrous ethanol and then added dropwise to solution A. The solution is reacted in a water bath at 60 °C for 1 h to obtain a nano-silver solution.

8. The method for fabricating a temperature-sensitive flexible sensor according to claim 7, characterized in that: In step (3), the volume ratio of glycerol, deionized water and binder is 4 mL: 2 mL: 2 mL.

9. The method for fabricating a temperature-sensitive flexible sensor according to claim 8, characterized in that: In step (3), the binder is one or more of waterborne polyurethane / polyacrylate, acrylic resin, and polyurethane.

Images