Ionic liquid flexible strain sensor based on mechanical metamaterial and preparation method thereof

Abstract

The invention discloses an ionic liquid flexible strain sensor based on a mechanical metamaterial and a preparation method of the ionic liquid flexible strain sensor. The sensor comprises two packaging layers, a flow channel layer and a mechanical metamaterial structure layer, the mechanical metamaterial structure layer is used for regulating and controlling a micro-column gap in a micro-flow channel of the flow channel layer so as to regulate and control the performance of the ionic liquid flexible strain sensor, the mechanical metamaterial structure layer is packaged in the packaging layers, the packaging layers are attached to the flow channel layer in a sealed mode, and the flow channel layer is filled with ionic liquid. Firstly, a mechanical metamaterial structure layer is obtained through a 3D printer and resin material printing; then preparing a packaging layer packaged with a mechanical metamaterial structure layer through a PDMS (Polydimethylsiloxane) mixed solution; finally, the packaging layer and the flow channel layer are attached and filled with an ionic liquid solution, sealing is conducted after a wire is inserted, and finally the ionic liquid flexible strain sensor is prepared and obtained. The flexible strain sensor has the characteristics of high sensitivity, wide range, low detection limit, adjustable Poisson ratio and the like, and can be suitable for receiving and monitoring strain signals in various scenes.

Description

Technical Field

[0001] The invention relates to a flexible strain sensor, and in particular to an ionic liquid flexible strain sensor based on mechanical metamaterials and a preparation method thereof. Background Art

[0002] Traditional strain sensors are mostly based on metal foil strain gauges or semiconductor strain gauges. Although their performance is relatively stable, they have obvious deficiencies in flexibility and ultra-sensitivity. On the other hand, the rapid development of organic materials and nanomaterials in recent years has brought new opportunities for the research of flexible strain sensors. However, the mechanical properties and sensing performance of these materials still face many challenges in practical applications. Summary of the invention

[0003] In order to solve the problems existing in the background technology, the present invention provides an ionic liquid flexible strain sensor based on mechanical metamaterials and a preparation method thereof. Due to its unique structural design, the mechanical metamaterial structure exhibits some mechanical properties that are difficult for natural materials to achieve, such as negative Poisson's ratio and adjustable elastic modulus. By optimizing the design of mechanical metamaterials, flexible strain sensors with extremely high strain sensitivity and wide strain range can be developed. The combination of mechanical metamaterials and flexible strain sensors aims to utilize the special structural design and excellent performance of mechanical metamaterials to significantly improve the strain sensitivity, detection range and low detection limit of the sensor, while maintaining high stretchability and flexibility.

[0004] The technical solution adopted by the present invention is:

[0005] 1. An ionic liquid flexible strain sensor based on mechanical metamaterials:

[0006] The ionic liquid flexible strain sensor includes two packaging layers, a flow channel layer, and a mechanical metamaterial structure layer for regulating the microcolumn gap in the microchannel of the flow channel layer and thus regulating the performance of the ionic liquid flexible strain sensor. The mechanical metamaterial structure layer is encapsulated in two packaging layers, one of which is sealed and attached to the flow channel layer. The flow channel layer is filled with ionic liquid as its conductive medium; the flow channel layer is electrically connected to an external signal sensing device through a wire. The ionic liquid flexible strain sensor is used to sense wrist and ankle rotation, speech pronunciation, etc.

[0007] The mechanical metamaterial structural layer is a hollow structure and is made of resin material.

[0008] A rectangular groove is provided at the center of one side surface of the flow channel layer, and a plurality of gated microchannel grooves are arranged in an array at intervals in the rectangular groove. The rectangular groove and each gated microchannel groove therein are filled with an ion solution, and a packaging layer is sealed and attached to the side surface of the flow channel layer where the rectangular groove is located; two through holes are opened on the symmetrical sides of the rectangular groove along the thickness direction of the flow channel layer and connected to the rectangular groove, one end of the two wires are respectively located in the two through holes, and the other ends of the two wires are electrically connected to an external signal sensing device.

[0009] 2. A method for preparing an ionic liquid flexible strain sensor based on mechanical metamaterials:

[0010] 1) The ionic solution is added into deionized water of different masses and mixed evenly to obtain an ionic liquid solution.

[0011] 2) Design a model of the mechanical metamaterial structure layer in SolidWorks, determine its geometric parameters, and then use a 3D printer and resin material to print out the mechanical metamaterial structure. Then, the mechanical metamaterial structure is successively vibrated and ultrasonically cleaned and then dried to obtain the mechanical metamaterial structure layer.

[0012] 3) Mixing polydimethylsiloxane (PDMS) and a curing agent and stirring them fully to obtain a polydimethylsiloxane (PDMS) mixed solution, dividing the polydimethylsiloxane (PDMS) mixed solution into three parts, pouring the first part of the polydimethylsiloxane (PDMS) mixed solution onto a silicon wafer mold printed with a microchannel pattern, degassing and heating the mixed solution in sequence, cooling the mixed solution to room temperature, and peeling off the mixed solution to obtain a channel layer; pouring the second part of the polydimethylsiloxane (PDMS) mixed solution into a glass culture dish, using a spin coater to evenly distribute the mixed solution to form a solution layer, degassing and heating the mixed solution in sequence, cooling the mixed solution to room temperature, and peeling off the mixed solution to obtain an encapsulation layer, placing the mechanical metamaterial structure layer on the first encapsulation layer, and then pouring the third part of the polydimethylsiloxane (PDMS) mixed solution onto the mechanical metamaterial structure layer, degassing and heating the mixed solution in sequence, cooling the mixed solution to room temperature, and forming a second encapsulation layer, and then cutting the two encapsulation layers and the mechanical metamaterial structure layer according to a preset size to obtain an encapsulation layer encapsulating the mechanical metamaterial structure layer.

[0013] 4) The side of the flow channel layer and the encapsulation layer encapsulating the mechanical metamaterial structure layer is bonded after hydrophilic treatment, and then the ionic liquid solution is filled into the rectangular groove of the flow channel layer and each gated microchannel groove therein, and then one end of the two wires are respectively inserted into the two through holes of the flow channel layer and sealed, and finally the ionic liquid flexible strain sensor is prepared.

[0014] In the step 1), the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate; the concentration of the ionic liquid solution is 50-70wt%, and the conductivity of the ionic liquid solutions of different concentrations is different, and the conductivity within the preset concentration range is better.

[0015] In the step 2), the mechanical metamaterial structure is placed in anhydrous ethanol and shaken for 30 seconds to shake out the residual resin material attached to the surface, and then placed in an ultrasonic cleaner for cleaning for 5 minutes, and finally taken out and dried at room temperature to obtain a mechanical metamaterial structure layer.

[0016] In the step 3), the mass ratio of polydimethylsiloxane PDMS to curing agent is 10:1; the polydimethylsiloxane PDMS mixed solution is divided into three parts of 4-8 mL, 4-8 mL and 3-5 mL respectively.

[0017] In the step 3), degassing and heating treatment are carried out in sequence, specifically placing in a vacuum environment to degas, and then placing in an oven at 80° C. for heat treatment for 1 hour.

[0018] In the step 4), the side of the flow channel layer and the packaging layer encapsulating the mechanical metamaterial structure layer is bonded to each other and subjected to surface hydrophilic treatment for 30 seconds in a plasma cleaning machine.

[0019] In the step 4), one end of the two wires are respectively inserted into the two through holes of the flow channel layer, and then two or three drops of resin glue are dripped into the two through holes to seal them. The two through holes are left to stand until the resin glue solidifies, and finally an ionic liquid flexible strain sensor is prepared.

[0020] The ionic liquid flexible strain sensor based on mechanical metamaterials of the present invention realizes the regulation of micro-column gaps in a microchannel by changing the distribution and structural parameters of the mechanical metamaterials, thereby achieving the purpose of regulating sensor performance.

[0021] The beneficial effects of the present invention are:

[0022] 1) The present invention combines a mechanical metamaterial structure with a gated microfluidic flexible strain sensor to achieve regulation of sensor performance, so that the sensor has the characteristics of high sensitivity, wide range, low detection limit and adjustable Poisson's ratio, and can be applied to the reception and monitoring of strain signals in a variety of application scenarios.

[0023] 2) The sensor of the present invention has an extremely low detection limit (0.0025%), which is more advantageous for small strain application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the flexible strain sensor of the present invention;

[0025] Figure 2 A schematic diagram of the shape and size of the flexible strain sensor microchannel of the present invention;

[0026] Figure 3 A physical picture of the flexible strain sensor of the present invention;

[0027] Figure 4 This is a test result diagram of the strain sensing sensitivity of the flexible strain sensor of the present invention;

[0028] Figure 5 This is a test result diagram of the response speed of the flexible strain sensor of the present invention;

[0029] Figure 6 This is a test result diagram of the flexible strain sensor of the present invention for small strain detection;

[0030] In the figure: 1. Packaging layer, 2. Mechanical metamaterial structure layer, 3. Flow channel layer. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, the ionic liquid flexible strain sensor based on mechanical metamaterials of the present invention comprises two packaging layers 1, a flow channel layer 3, and a mechanical metamaterial structure layer 2 for regulating the microcolumn gap in the microchannel of the flow channel layer 3 and thus regulating the performance of the ionic liquid flexible strain sensor. The mechanical metamaterial structure layer 2 is encapsulated in the two packaging layers 1, one of which is sealed and attached to the flow channel layer 3, and the flow channel layer 3 is filled with ionic liquid as its conductive medium; the flow channel layer 3 is electrically connected to an external signal sensing device through a wire. The ionic liquid flexible strain sensor is used to sense wrist and ankle rotation, speech pronunciation, etc. The mechanical metamaterial structure layer 2 is a hollow structure and is made of resin material.

[0033] A rectangular groove is provided at the center of one side surface of the flow channel layer 3, and a number of gated microchannel grooves are arranged in an array at intervals in the rectangular groove. The rectangular groove and each gated microchannel groove therein are filled with an ion solution, and one encapsulation layer 1 is sealed and adhered to the side surface of the flow channel layer 3 where the rectangular groove is located; two through holes are opened on the symmetrical sides of the rectangular groove along the thickness direction of the flow channel layer 3 and connected to the rectangular groove, one end of the two wires are respectively located in the two through holes, and the other ends of the two wires are electrically connected to an external signal sensing device.

[0034] The specific embodiments of the present invention are as follows:

[0035] Embodiment 1:

[0036] 1) The ion solution was added into deionized water and mixed evenly to obtain a 1-ethyl-3-methylimidazolium tetrafluoroborate solution with a concentration of 60 wt %.

[0037] 2) Design a model of the mechanical metamaterial structure layer 2 in SolidWorks, determine its geometric parameters, and then use a 3D printer and Flexible 80A flexible resin material to print out the mechanical metamaterial structure. Then, place the mechanical metamaterial structure in anhydrous ethanol and shake it for 30 seconds to shake out the residual resin material attached to the surface. Then, place it in an ultrasonic cleaner for cleaning for 5 minutes. Finally, take it out and dry it at room temperature to obtain the mechanical metamaterial structure layer 2.

[0038] 3) Mix polydimethylsiloxane (PDMS) and curing agent in a mass ratio of 10:1 and stir them thoroughly for 5 minutes to obtain 14 mL of polydimethylsiloxane (PDMS) mixed solution, and divide the polydimethylsiloxane (PDMS) mixed solution into three parts of 5 mL, 5 mL and 4 mL. Pour the first part of the polydimethylsiloxane (PDMS) mixed solution onto a silicon wafer mold printed with a microchannel pattern, and then place it in a vacuum environment to remove bubbles, and then place it in an 80°C oven for heat treatment for 1 hour and then cool it to room temperature, and peel it off to obtain the channel layer 3; pour the second part of the polydimethylsiloxane (PDMS) mixed solution into a glass culture dish and use a spin coater to spin coat it at a speed of 300 r / min for 1 mi n is evenly distributed to form a solution layer, which is then placed in a vacuum environment to remove bubbles, and then placed in an oven at 80°C for heat treatment for 1 hour and then cooled to room temperature, and peeled off to obtain a packaging layer 1, and the mechanical metamaterial structure layer 2 is placed on the first packaging layer 1 and then the third part of the polydimethylsiloxane PDMS mixed liquid is poured on the mechanical metamaterial structure layer 2, and then placed in a vacuum environment to remove bubbles, and then placed in an oven at 80°C for heat treatment for 1 hour and then cooled to room temperature to form a second packaging layer 1, and then the two packaging layers 1 and the mechanical metamaterial structure layer 2 are cut into a length of 30 mm and a width of 8 mm to obtain a packaging layer 1 encapsulating the mechanical metamaterial structure layer 2.

[0039] 4) The side of the flow channel layer 3 and the encapsulation layer 1 encapsulating the mechanical metamaterial structure layer 2 is bonded to each other, and then the surface is hydrophilized in a plasma cleaning machine for 30 seconds before bonding. Then, the ionic liquid solution is filled into the rectangular groove of the flow channel layer 3 and each gated microchannel groove therein, and then one end of the two conductive copper wires is respectively inserted into two through holes with a diameter of 1 mm in the flow channel layer 3. A multimeter is used to detect whether there is a resistance signal at both ends of the conductive copper wires. If there is a resistance signal, it means that the ionic liquid has filled the microchannel, and then three drops of resin glue are dripped into the through hole for sealing, and the resin glue is allowed to stand until it solidifies, and finally the preparation is obtained. Figure 3 The ionic liquid flexible strain sensor shown; Figure 2As shown, two interconnected small grooves are provided on the symmetrical sides of the rectangular groove of the channel layer 3, and a through hole is provided in each small groove. The total length of the rectangular groove and the two small grooves is 14 mm, the wide side of the gated microfluidic channel array is 2 mm away from the wide side of the rectangular groove, the edge of the small groove is 1 mm away from the long side of the rectangular groove, the gated microfluidic channel is a square with a side length of 0.6 mm, the gated microfluidic channel close to the long side of the rectangular groove is 0.4 mm away from the long side of the rectangular groove, and the distance between every two adjacent gated microfluidic channels is 0.32 mm.

[0040] Embodiment 2:

[0041] 1) The ion solution is added into deionized water and mixed uniformly to obtain a 1-ethyl-3-methylimidazolium tetrafluoroborate solution with a concentration of 50 wt %.

[0042] 2) Design a model of the mechanical metamaterial structure layer 2 in SolidWorks, determine its geometric parameters, and then use a 3D printer and Flexible 80A flexible resin material to print out the mechanical metamaterial structure. Then, place the mechanical metamaterial structure in anhydrous ethanol and shake it for 30 seconds to shake out the residual resin material attached to the surface. Then, place it in an ultrasonic cleaner for cleaning for 5 minutes. Finally, take it out and dry it at room temperature to obtain the mechanical metamaterial structure layer 2.

[0043] 3) Mix polydimethylsiloxane (PDMS) and curing agent in a mass ratio of 10:1 and stir them thoroughly for 5 minutes to obtain 17 mL of polydimethylsiloxane (PDMS) mixed solution, and divide the polydimethylsiloxane (PDMS) mixed solution into three parts of 6 mL, 6 mL and 5 mL. Pour the first part of the polydimethylsiloxane (PDMS) mixed solution onto a silicon wafer mold printed with a microchannel pattern, and then place it in a vacuum environment to remove bubbles, and then place it in an 80°C oven for heat treatment for 1 hour and then cool it to room temperature, and peel it off to obtain the channel layer 3; pour the second part of the polydimethylsiloxane (PDMS) mixed solution into a glass culture dish and use a spin coater to spin coat it at a speed of 300 r / min for 1 mi n is evenly distributed to form a solution layer, which is then placed in a vacuum environment to remove bubbles, and then placed in an oven at 80°C for heat treatment for 1 hour and then cooled to room temperature, and peeled off to obtain a packaging layer 1, and the mechanical metamaterial structure layer 2 is placed on the first packaging layer 1 and then the third part of the polydimethylsiloxane PDMS mixed liquid is poured on the mechanical metamaterial structure layer 2, and then placed in a vacuum environment to remove bubbles, and then placed in an oven at 80°C for heat treatment for 1 hour and then cooled to room temperature to form a second packaging layer 1, and then the two packaging layers 1 and the mechanical metamaterial structure layer 2 are cut into a length of 30 mm and a width of 8 mm to obtain a packaging layer 1 encapsulating the mechanical metamaterial structure layer 2.

[0044] 4) The side of the flow channel layer 3 and the packaging layer 1 encapsulating the mechanical metamaterial structure layer 2 is bonded to each other, and the surface is hydrophilized in a plasma cleaning machine for 30 seconds before bonding. Then, the ionic liquid solution is filled into the rectangular groove of the flow channel layer 3 and each gated microchannel groove therein, and then one end of the two conductive copper wires are respectively inserted into the two through holes with a diameter of 1 mm in the flow channel layer 3. A multimeter is used to detect whether there is a resistance signal at both ends of the conductive copper wires. If there is a resistance signal, it means that the ionic liquid has filled the microchannel, and then three drops of resin glue are dripped into the through hole to seal it. Let it stand until the resin glue solidifies, and finally prepare the ionic liquid flexible strain sensor.

[0045] The flexible strain sensor prepared in Example 1 was tested for strain sensing sensitivity, and its performance was compared with that of a gated microfluidic strain sensor that does not include a mechanical metamaterial structure. The test results are as follows: Figure 4 As shown, the horizontal axis represents the stretching amount (in %), and the vertical axis represents the resistance change rate. Among them, the sensitivity (Gauge Factor, referred to as GF) calculation formula is GF = ΔR / R0 / Δε, where ΔR and R0 are the resistance change and initial resistance respectively, Δε is the stretching amount, GF1, GF2 and GF3 represent the sensor sensitivity in different strain ranges respectively. It can be seen that the perforated plate is a metamaterial structure, and the single and double perforated plates are different arrangements of the metamaterial when preparing the sensor. The Poisson's ratio of the strain sensor is changed by the perforated plate to achieve adjustable Poisson's ratio, thereby achieving the effect of adjustable high sensitivity area. It can be seen from the curve that the double perforated plate arrangement can simultaneously achieve the left shift of the high sensitivity area and improve the sensitivity of the sensor in all sensing ranges. In contrast, although the single perforated plate can achieve the right shift of the high sensitivity area, the overall sensitivity is reduced.

[0046] The response speed test of the flexible strain sensor prepared in Example 1 was carried out. Figure 5 As shown, the ordinate represents the resistance change rate, the left rectangular box area represents the change of the resistance change rate over time during stretching, and the right rectangular box area represents the change of the resistance change rate over time during contraction. The measured response time and recovery time are 100ms and 200ms, respectively. It can be seen that the flexible strain sensor of the present invention has a high response time and recovery time.

[0047] The flexible strain sensor prepared in Example 1 was subjected to a minimum strain test. Figure 6 As shown, the percentage on the test result curve represents the resistance change rate response under the strain. It can be seen that the prepared strain sensor can detect an extremely small strain of 0.0025%, and can still detect an extremely small strain of 0.0025% under a certain pre-stretching condition.

[0048] This embodiment does not limit the specific thickness, length and width of the packaging layer 1, the mechanical metamaterial structure layer 2 and the flow channel layer 3, and they can be adjusted according to actual needs.

[0049] This embodiment does not limit the material type of the mechanical metamaterial structure layer 2 , for example, including but not limited to flexible resin (Flexible 80A) and elastic resin (Elastic 50A).

[0050] This embodiment does not limit the specific type and concentration of the ionic liquid, for example, including but not limited to 1-ethyl-3-methylimidazolium tetrafluoroborate with a concentration of 60 wt %, as long as it has good conductivity and stability, it can be used as a conductive medium.

[0051] This embodiment does not limit the specific shape and size of the gated microfluidic channel pattern. It should be particularly noted that the channel size should not be too large, otherwise it will affect the size and performance of the sensor.

[0052] The contents described in the embodiments of this specification are merely an enumeration of implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms described in the examples. The protection scope of the present invention also includes equivalent technical means that can be thought of by those skilled in the art based on the inventive concept.

[0053] In summary, it can be seen that the present invention has good comprehensive performance. Since the present invention has the characteristics of high fit with the part to be tested, wide detection range, fast response (100ms), extremely low detection limit (0.0025%), adjustable Poisson's ratio, etc., and the sensor has low production cost, easy material acquisition, and simple production method. The excellent comprehensive performance and simple production method make the sensor applicable to a variety of application scenarios and have great potential.

Claims

1. An ionic liquid flexible strain sensor based on mechanical metamaterials, characterized in that: The invention comprises two packaging layers (1), a flow channel layer (3), and a mechanical metamaterial structure layer (2) for regulating the micro-column gap in the micro-channel of the flow channel layer (3) and thereby regulating the performance of the ionic liquid flexible strain sensor. The mechanical metamaterial structure layer (2) is packaged in the two packaging layers (1), one of the packaging layers (1) is sealed and attached to the flow channel layer (3), and the flow channel layer (3) is filled with ionic liquid as its conductive medium. The flow channel layer (3) is electrically connected to an external signal sensing device via a wire.

2. The ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 1, characterized in that: The mechanical metamaterial structure layer (2) is a hollow structure and is made of resin material.

3. The ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 1, characterized in that: A rectangular groove is provided at the center of one side of the flow channel layer (3), and a plurality of gated microchannel grooves are arranged in an array at intervals in the rectangular groove. The rectangular groove and each gated microchannel groove therein are filled with an ion solution, wherein a packaging layer (1) is sealed and attached to the side of the flow channel layer (3) where the rectangular groove is located; two through holes are provided on the symmetrical sides of the rectangular groove along the thickness direction of the flow channel layer (3) and connected to the rectangular groove, one end of two wires are respectively located in the two through holes, and the other ends of the two wires are electrically connected to an external signal sensing device.

4. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to any one of claims 1 to 3, characterized in that: include: 1) adding the ionic solution into deionized water and uniformly mixing to obtain an ionic liquid solution; 2) using a 3D printer and a resin material to print out a mechanical metamaterial structure, and then sequentially vibrating and ultrasonically cleaning the mechanical metamaterial structure and then drying it to obtain a mechanical metamaterial structure layer (2); 3) Mixing polydimethylsiloxane (PDMS) and a curing agent and stirring them thoroughly to obtain a polydimethylsiloxane (PDMS) mixed solution, dividing the polydimethylsiloxane (PDMS) mixed solution into three parts, pouring the first part of the polydimethylsiloxane (PDMS) mixed solution onto a silicon wafer mold printed with a microchannel pattern, degassing and heating the mixture, cooling the mixture to room temperature, and peeling the mixture to obtain a channel layer (3); pouring the second part of the polydimethylsiloxane (PDMS) mixed solution into a glass culture dish to form a solution layer, degassing and heating the mixture, and then After the heat treatment, the mixture is cooled to room temperature, peeled off to obtain a packaging layer (1), the mechanical metamaterial structure layer (2) is placed on the first packaging layer (1), and then the third part of the polydimethylsiloxane (PDMS) mixed liquid is poured on the mechanical metamaterial structure layer (2), and then the mixture is de-bubbled and heated in sequence and then cooled to room temperature to form a second packaging layer (1), and then the two packaging layers (1) and the mechanical metamaterial structure layer (2) are cut according to a preset size to obtain a packaging layer (1) encapsulating the mechanical metamaterial structure layer (2); 4) The side of the flow channel layer (3) and the encapsulation layer (1) encapsulating the mechanical metamaterial structure layer (2) is bonded to each other after being hydrophilic treated, and then the ionic liquid solution is filled into the rectangular groove of the flow channel layer (3) and each gated microchannel groove therein, and then one end of the two wires are respectively inserted into the two through holes of the flow channel layer (3) and sealed, and finally the ionic liquid flexible strain sensor is prepared.

5. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 4, characterized in that: In the step 1), the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate; and the concentration of the ionic liquid solution is 50-70 wt%.

6. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 4, characterized in that: In the step 2), the mechanical metamaterial structure is placed in anhydrous ethanol and shaken for 30 seconds, then placed in an ultrasonic cleaning machine for cleaning for 5 minutes, and finally taken out and dried at room temperature to obtain a mechanical metamaterial structure layer (2).

7. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 4, characterized in that: In the step 3), the mass ratio of polydimethylsiloxane PDMS to curing agent is 10:1; the polydimethylsiloxane PDMS mixed solution is divided into three parts of 4-8 mL, 4-8 mL and 3-5 mL respectively.

8. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 4, characterized in that: In the step 3), degassing and heating treatment are carried out in sequence, specifically placing in a vacuum environment to degas, and then placing in an oven at 80° C. for heat treatment for 1 hour.

9. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 4, characterized in that: In the step 4), the side of the flow channel layer (3) and the packaging layer (1) encapsulating the mechanical metamaterial structure layer (2) is bonded to each other and subjected to surface hydrophilic treatment for 30 seconds in a plasma cleaning machine.

10. The method for preparing the ionic liquid flexible strain sensor based on mechanical metamaterial according to claim 4, characterized in that: In the step 4), one end of the two wires is respectively inserted into the two through holes of the flow channel layer (3), and then two or three drops of resin glue are dripped into the two through holes to seal them. The two through holes are left to stand until the resin glue solidifies, and finally the ionic liquid flexible strain sensor is prepared.

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