A highly sensitive piezoresistive flexible strain sensor and its dynamic characteristics simulation optimization method

Abstract

The present invention provides a highly sensitive piezoresistive flexible strain sensor and a method for simulating and optimizing its dynamic characteristics, and belongs to the field of flexible sensors. The invention solves the limitation that the existing piezoresistive flexible strain sensors can only be optimized by static simulation. The flexible strain sensor of the present invention has a topological microstructure, and the strain field is reshaped after being loaded, thereby achieving higher sensitivity. The flexible strain sensor mainly includes a conductive part, a non-conductive part, and a signal line. The dynamic characteristics simulation and optimization method for such sensors of the present invention uses APDL to realize structural-electrical coupling simulation, has high accuracy, and can provide intuitive and effective prediction for the dynamic characteristics optimization design of piezoresistive flexible strain sensors, thereby improving the efficiency of sensor design.

Description

Technical Field

[0001] The present invention belongs to the field of flexible sensors, and in particular relates to a highly sensitive piezoresistive flexible strain sensor and a method for simulating and optimizing its dynamic characteristics. Background Art

[0002] Soft robots have gradually become a hot topic in the field of robotics in recent years due to their good compliance and safe interaction. However, due to the limitations of nonlinearity and large compliant deformation, the control method based on the quasi-static equilibrium model is not competent in complex and restricted environments, especially in the presence of external disturbances. In order to improve the flexibility and controllability of soft robots, it is necessary to give soft robots body perception capabilities similar to those of biological organisms to feedback information about themselves and the surrounding environment.

[0003] Piezoresistive flexible strain sensors have the advantages of high sensitivity and large strain sensing range, and are widely used in proprioception of soft robots. Sensitivity (GF) is an important indicator for evaluating the performance of sensors. Scholars mainly improve it from two aspects: materials and structures. In terms of materials, conductive fillers with high conductivity and high aspect ratio (such as silver flakes, Mexene, etc.) are generally selected, and their dispersion (such as ultrasonic assisted vibration) is improved. In terms of structure, some topological microstructures are mainly designed, such as origami and grid, and the size parameters are optimized. Theoretical models can make relatively accurate predictions of the dynamic characteristics of sensors, but are limited to simple shapes. For complex shapes (such as origami and grid), finite element simulation is often used to avoid tedious and repetitive characterization experiments. However, the current simulation of piezoresistive flexible sensors is limited to static analysis, and structural-electrical coupling simulation is not realized. It is impossible to directly obtain the resistance value after applying displacement load like the characterization test, so it is impossible to make intuitive and accurate predictions of the dynamic characteristics of piezoresistive flexible sensors. The main reason is that the irregular structure has non-uniform strain distribution under the action of external load, which in turn causes non-uniform resistivity distribution. During the stretching process, this non-uniform resistivity changes continuously, increasing the difficulty of structure-electrical coupling simulation. Summary of the invention

[0004] The present invention provides a highly sensitive piezoresistive flexible strain sensor and a dynamic characteristic simulation optimization method thereof, which are used to solve the problem that the dynamic characteristics of the piezoresistive flexible sensor cannot be intuitively and accurately predicted and optimize the sensor structural parameters.

[0005] The present invention is achieved through the following technical solutions:

[0006] A highly sensitive piezoresistive flexible strain sensor, the sensor comprising a conductive part 1, a non-conductive part 2 and a signal line 3, the conductive part 1 is provided with a hollowed-out and penetrating non-conductive part 2, the conductive part 1 passes through the signal line 3, and the conductive part 1 has a topological microstructure;

[0007] The conductive part 1 comprises a flexible substrate and a conductive filler layer;

[0008] The moduli of the conductive part 1 and the non-conductive part 2 have a certain gradient, and the two are seamlessly connected by molecular bonding during the preparation process. The moduli of the array micro-units of the non-conductive part 2 are the same or different.

[0009] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, the dynamic characteristic simulation optimization method comprising the following steps:

[0010] Step 1: Establish an equivalent circuit for the highly sensitive piezoresistive flexible strain sensor;

[0011] Step 2: Based on the equivalent circuit in step 1, define the material-related information of the piezoresistive flexible strain sensor through APDL;

[0012] Step 3: Establish a finite element model of the piezoresistive flexible strain sensor through APDL;

[0013] Step 4: Based on the material-related information in step 2 and the finite element model in step 3, a structural statics-electrical simulation calculation parameter interface is established to carry out structural-electrical coupling simulation analysis of the piezoresistive flexible sensor.

[0014] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein the sensor in step 1 is equivalent to a plurality of resistors connected in series and in parallel, and the overall resistance of the sensor can be expressed as:

[0015]

[0016] The parallel resistance is represented by R mn , m and n represent the number of rows and columns of this part of the resistance respectively, and the series resistance is represented by R n , R j+1 ; i represents the total number of rows of non-conductive parts plus 1, and j represents the total number of columns of non-conductive parts.

[0017] A dynamic characteristics simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein the material-related information in step 2 specifically includes mechanical characteristics and electrical characteristics;

[0018] The constitutive equation of the mechanical properties of the material adopts the third-order Mooney-Rivlin model:

[0019] W=C 10 (I 1 -3)+C 01 (I 2 -3)+C 20 (I 1 -3)2

[0020] Where W is the strain energy density, I 1 ,I 2 The principal moments of inertia, C 10 , C 01 , C 20 is a constant.

[0021] The resistivity-strain relationship model of the electrical characteristics adopts the Kraus model:

[0022]

[0023] Where ρ is the dynamic resistivity during stretching, ρ 0 is the initial resistivity, m, ε c are constants related to fractal and yield strain respectively.

[0024] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein the corresponding node positions of the contact interface between the conductive part and the non-conductive part in step 3 are kept consistent, and then the nummrg command is used to merge the finite element model nodes of the conductive part and the non-conductive part.

[0025] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein in step 4, when performing simulation analysis, a *do loop is used for iterative calculation; electrical simulation is used as the main program, and statics simulation is used as a subroutine. In each iterative process, when performing statics simulation, the etable command is used to extract the strain of each unit of the conductive part 1 obtained by the statics analysis; the *get command is used to save it to an array parameter; parsav is used to save all parameters; when performing electrical simulation, the upgeom command is used to update the node coordinates of the sensor finite element model, and the resistivity of each unit of the conductive part 1 is updated based on the Kraus model; both statics and electricity are solved using the preconditioned conjugate gradient iterative solver PCG.

[0026] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein step 4 obtains the voltage value at both ends of the sensor by applying 0 potential to one end node of the sensor and 1A current load to the other end node, and according to Ohm's law, it is equivalent to the resistance value.

[0027] A dynamic characteristic simulation optimization method for a high-sensitivity piezoresistive flexible strain sensor is proposed. Among the end face nodes where current load is applied, the edge vertex nodes, edge non-vertex nodes, and non-edge nodes are allocated 1A current load in a ratio of 4:2:1.

[0028] The beneficial effects of the present invention are:

[0029] The flexible strain sensor of the present invention realizes the reshaping of the strain field during the stretching process through the deployment of topological microstructure and material properties, has both high sensitivity and high flexibility, and can be seamlessly integrated with soft robots.

[0030] The dynamic characteristics simulation optimization method based on APDL in the present invention can perform parallel optimization of topological microstructure and material deployment, directly obtain the resistance value by applying axial displacement load, and intuitively and accurately predict the dynamic characteristics of piezoresistive flexible strain sensors, breaking through the limitation that the existing simulation optimization of such sensor parameters can only perform static simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the present invention.

[0032] Figure 2 Schematic diagram of equivalent series-parallel resistance of the sensor of the present invention.

[0033] Figure 3 This is a schematic diagram of the APDL-based dynamic characteristics simulation optimization method of the piezoresistive flexible strain sensor of the present invention.

[0034] Figure 4 It is a schematic diagram of the simulation optimization result of the sensor topology configuration of the present invention, wherein Figure 4 -(a) is the simulation optimization result diagram of optimizing the number of rows and columns of the non-conductive part. Figure 4 -(b) is the dimension diagram of the optimized non-conductive part.

[0035] Figure 5 This is a diagram of the simulation optimization results of the sensor material property distribution of the present invention.

[0036] Figure 6 It is a comparison chart of the simulation and experimental results of the dynamic characteristics of the sensor of the present invention. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] A highly sensitive piezoresistive flexible strain sensor, the sensor comprising a conductive part 1, a non-conductive part 2 and a signal line 3, the conductive part 1 is provided with a hollowed-out and penetrating non-conductive part 2, the conductive part 1 passes through the signal line 3, and the conductive part 1 has a topological microstructure;

[0039] The conductive part 1 comprises a flexible substrate and a conductive filler layer;

[0040] The moduli of the conductive part 1 and the non-conductive part 2 have a certain gradient, that is, the modulus of the latter is lower than that of the former, and the two are seamlessly connected by molecular bonding during the preparation process, such as conductive silicone and silicone, hydrogel and silicone, etc. The modulus of the array microunits of the non-conductive part 2 is the same or different.

[0041] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, the dynamic characteristic simulation optimization method comprising the following steps:

[0042] Step 1: Establish an equivalent circuit for the highly sensitive piezoresistive flexible strain sensor;

[0043] Step 2: Based on the equivalent circuit in step 1, define the material-related information of the piezoresistive flexible strain sensor through APDL;

[0044] Step 3: Establish a finite element model of the piezoresistive flexible strain sensor through APDL;

[0045] Step 4: Based on the material-related information in step 2 and the finite element model in step 3, a structural statics-electrical simulation calculation parameter interface is established to carry out structural-electrical coupling simulation analysis of the piezoresistive flexible sensor.

[0046] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein the sensor in step 1 is equivalent to a plurality of resistors connected in series and in parallel, and the overall resistance of the sensor can be expressed as:

[0047]

[0048] The parallel resistance is represented by R mn , m and n represent the number of rows and columns of this part of the resistance respectively, and the series resistance is represented by R n , R j+1 ; i represents the total number of rows of non-conductive parts plus 1, and j represents the total number of columns of non-conductive parts.

[0049] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein the material-related information in step 2 specifically includes material mechanical properties and electrical properties; the material mechanical properties include density, constitutive equations and characteristic parameters; the electrical properties include initial resistivity, resistivity-strain relationship model and characteristic parameters;

[0050] The constitutive equation of the mechanical properties of the material adopts the third-order Mooney-Rivlin model:

[0051] W=C 10 (I 1 -3)+C 01 (I 2-3)+C 20 (I 1 -3) 2

[0052] Where W is the strain energy density, I 1 ,I 2 The principal moments of inertia, C 10 , C 01 , C 20 is a constant and can be obtained by fitting the tensile test data;

[0053] The resistivity-strain relationship model of the electrical characteristics adopts the Kraus model:

[0054]

[0055] Where ρ is the dynamic resistivity during stretching, ρ 0 is the initial resistivity, m, ε c are constants related to fractal and yield strain respectively. 0 , m, ε c , m, ε c It can be obtained by experimental calibration of specimens without topological microstructures.

[0056] A dynamic characteristic simulation and optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein the step 2 establishes two-dimensional finite element models of a conductive part and a non-conductive part respectively, and then stretches them into a three-dimensional finite element model, keeps the corresponding node positions of the contact interface between the two consistent, uses the aclear command to clear the surface mesh, and then uses the nummrg command to merge the finite element model nodes of the conductive part and the non-conductive part.

[0057] A dynamic characteristic simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein in step 3, when performing simulation analysis, a *do loop is used for iterative calculation; electrical simulation is used as the main program, and statics simulation is used as a subroutine. In each iterative process, when performing statics simulation, the strain of each unit of the conductive part 1 obtained by the statics analysis is extracted using the etable command; the strain is saved in an array parameter using the *get command; all parameters are saved using parsav to avoid loss when the electrical simulation clears the database; when performing electrical simulation, the upgeom command is used to update the node coordinates of the sensor finite element model, and the resistivity of each unit of the conductive part 1 is updated based on the Kraus model; both statics and electricity are solved using the preconditioned conjugate gradient iterative solver PCG.

[0058] A dynamic characteristics simulation and optimization method for a highly sensitive piezoresistive flexible strain sensor, wherein step 3 obtains the voltage value at both ends of the sensor by applying 0 potential to one end node of the sensor and 1A current load to the other end node, and according to Ohm's law, it is equivalent to the resistance value.

[0059] A dynamic characteristic simulation optimization method for a high-sensitivity piezoresistive flexible strain sensor is proposed. Among the end face nodes where current load is applied, the edge vertex nodes, edge non-vertex nodes, and non-edge nodes are allocated 1A current load in a ratio of 4:2:1.

[0060] like Figure 1 As shown, a highly sensitive piezoresistive flexible strain sensor has a topological microstructure, including a conductive part, a non-conductive part, and a signal line.

[0061] The piezoresistive flexible sensor has a square shape with a side length of L. 0 =10mm, thickness is 1.5mm. The conductive part contains 4wt% multi-walled carbon nanotubes, 8wt% carbon nanofibers as conductive fillers and silicone (model Ecoflex20) as a flexible substrate, the non-conductive part is silicone (model HY 00), with a size of 3mm×0.3mm, distributed in a 5×1 array in the piezoresistive flexible sensor, and the wire is an enameled wire with a diameter of 0.08mm, located at both ends of the axis direction of the flexible sensor.

[0062] like Figure 2 As shown, the piezoresistive flexible strain sensor with topological microstructure can be equivalent to multiple resistors connected in series and in parallel, and the parallel resistors are represented by R ij (i, j are the row and column numbers of this part of the resistance respectively), the series resistance is represented by R j . R ij The length of the sensor is a and the width is b. The overall resistance of the sensor can be expressed as:

[0063]

[0064] When strain ε=L / L 0 = 0, all parallel resistances are equal, and the series resistances are also equal, that is, R 11 =R 12 =… =R i2 =R ij ,R 1 =R 2 =…R j =R j+1 , when the strain ε≠0, the axisymmetric resistance values ​​are equal, that is, (R 11 =R i1 =R ij =R ij )≠…≠(R21 =R (i-1)1 =R 2j =R 2j ),(R 1 =R j+1 )≠…≠(R 2 =R j ).

[0065] The moduli of the conductive part and the non-conductive part have a certain gradient (the modulus of the conductive part is 116 kPa, and the modulus of the non-conductive part is 39 kPa). The same material properties of the two enable them to be seamlessly connected through molecular bonding during the preparation process.

[0066] like Figure 3 As shown, the dynamic characteristics simulation optimization method of the highly sensitive piezoresistive flexible strain sensor comprises the following steps:

[0067] (1) The simulated displacement of the sensor is set to 8 mm (ε = 0.8), a 0 =1mm, b 0 =1mm, i∈(2,3,4,5), j∈(1,2,3,4), the number of iterations is 10, start the *do loop;

[0068] (2) Define the relevant information of the piezoresistive sensor model through APDL, including material mechanical properties (density, constitutive equation and characteristic parameters) and electrical properties (initial resistivity, resistivity-strain relationship model and characteristic parameters);

[0069] (3) Establish a finite element model of piezoresistive flexible strain sensor through APDL;

[0070] (4) Perform static simulation through APDL to extract the unit strain value of the conductive part;

[0071] (5) Conduct electrical simulation through APDL, read the deformed finite element model, update the resistivity of the conductive part unit, apply current load, and solve;

[0072] (6) End the *do loop

[0073] In step (1), the displacement iteration step length ΔL=0.8 mm.

[0074] In step (2), the material density is defined using the mp command, and the constitutive equation adopts the third-order Mooney-Rivlin model:

[0075] W=C 10 (I 1 -3)+C 01 (I 2 -3)+C 20 (I 1 -3)2

[0076] Where W is the strain energy density, I 1 ,I 2 The principal moments of inertia, C 10 , C 01 , C 20 is a constant that can be obtained by fitting the tensile test data and is defined by the tb and tbdata commands.

[0077] The resistivity-strain relationship model adopts the Kraus model:

[0078]

[0079] Where ρ is the dynamic resistivity during stretching, ρ 0 is the initial resistivity, m, ε c are the constants related to fractal and yield strain, ρ 0 , m, ε c , m, ε c It can be obtained by experimental calibration of the specimen without topological microstructure, ρ 0 =5.4Ω·m,ε c =0.01, m=2.68, n ε =0.03.

[0080] In step (3), the finite element model uses a hexahedral mesh. First, two-dimensional finite element models of the conductive part and the non-conductive part are established separately, and then stretched into a three-dimensional finite element model. The corresponding node positions of the contact interface of the two are kept consistent. The surface mesh is cleared using the aclear command, and the contact interface nodes are merged using the nummrg command.

[0081] In step (4), the displacements of the nodes at one end of the sensor in the three directions are all defined as zero, the displacement of the nodes at the other end in the x direction is defined as ΔL, and the displacements in the other two directions are defined as zero. When solving, use the nlgeom command to turn on the large deformation switch, and use the preconditioned conjugate gradient iterative solver PCG for solving. After the solution is completed, use the etable command to extract the strain of each unit of the conductive part, use the *vget command to save the node number of the conductive part to the array parameter, use the etable command to extract the unit strain, use *get to save the unit strain to the array parameter, and use the parsav command to save all parameters to avoid loss when the electrical simulation clears the database.

[0082] In step (5), the upgeom command is used to read the deformed sensor finite element model, and the resistivity of each unit of the conductive part is updated based on the Kraus model. When solving, the f command is used to apply a 0 potential to one end node of the sensor and a 1A current load to the other end node to obtain the voltage value at both ends of the sensor. According to Ohm's law, it is equivalent to the resistance value.

[0083] In step (5), among the end face nodes to which the current load is applied, the edge vertex nodes, edge non-vertex nodes, and non-edge nodes are allocated a 1A current load in a ratio of 4:2:1.

[0084] like Figure 4 As shown in a, first optimize the parameters i and j, and repeat the above steps (1) to (6). When i=5 and j=1, the GF of the sensor is the largest, which is 8.98.

[0085] like Figure 4 As shown in b, the parameters a and b are then optimized and the above steps (1) to (6) are repeated. When a=3 mm and b=0.1 mm, the GF of the sensor is the largest, which is 19.44. Compared with the GF of the sensor without topological microstructure (pure filling), it is increased by 101.5%.

[0086] like Figure 5 As shown in the figure, considering the existing processing technology, the minimum value of b is 0.3mm. On this basis, the modulus of the non-conductive part is optimized, and four silicones with different elastic moduli, HY 00 (39kPa), HY 05 (72kPa), HY 10 (106kPa), and CEcoflex 20 (116kPa, only the mechanical properties of the conductive part silicone are used, and its conductivity is set to 0, that is, 1 / ρ=0) are compared with the sensor without topological microstructure. It can be seen that the lower the modulus of the non-conductive part, the higher the sensitivity of the sensor. Compared with the sensor without topological microstructure, the GF of the sensor with HY 00 silicone as the non-conductive part is increased by 42.5%.

[0087] like Figure 6 As shown in the figure, based on the above preferred parameters (i=5, j=1, a=3mm, b=0.3mm), the experimental values ​​and simulations of the specimens with topological microstructures and the specimens without topological microstructures are compared. It can be seen that the simulation values ​​are close to the experimental values, which shows the accuracy of the simulation method. In the experimental results, in the strain range of 0-0.4, the GF with hollow microstructure is 8.51, and the GF without hollow microstructure is 5, and the GF is relatively increased by 70.2%; in the range of 0.4-0.8, the GF with hollow microstructure is 15.9, and the GF without hollow microstructure is 10.9, and the GF is relatively increased by 45.9%.

Claims

1. A dynamic characteristics simulation optimization method for a highly sensitive piezoresistive flexible strain sensor, characterized in that: The highly sensitive piezoresistive flexible strain sensor comprises a conductive part (1), a non-conductive part (2) and a signal line (3); the conductive part (1) is provided with a hollowed-out and penetrating non-conductive part (2); the signal line (3) passes through the conductive part (1); and the conductive part (1) has a topological microstructure; the conductive part (1) comprises a flexible substrate and a conductive filler layer; the non-conductive part is distributed in an array in the piezoresistive flexible sensor; the moduli of the conductive part (1) and the non-conductive part (2) have a certain gradient, and the conductive part (1) and the non-conductive part (2) are seamlessly connected by molecular bonding; the moduli of the array microunits of the non-conductive part (2) are the same or different; The dynamic characteristics simulation optimization method comprises the following steps: Step 1: Establish an equivalent circuit for the highly sensitive piezoresistive flexible strain sensor; Step 2: Based on the equivalent circuit in step 1, define the material-related information of the piezoresistive flexible strain sensor through APDL; Step 3: Establish a finite element model of the piezoresistive flexible strain sensor through APDL; Step 4: Based on the material-related information in step 2 and the finite element model in step 3, establish a structural statics-electrical simulation calculation parameter interface, carry out structural-electrical coupling simulation analysis of the piezoresistive flexible sensor, and optimize the number of rows and columns and the size of the non-conductive part; The sensor in step 1 is equivalent to multiple resistors connected in series and parallel, and the overall resistance of the sensor is expressed as: The parallel resistance is represented by R mn , m and n represent the number of rows and columns of this part of the resistance respectively, and the series resistance is represented by R n , R j+1 ; i represents the total number of rows of non-conductive parts plus 1, and j represents the total number of columns of non-conductive parts.

2. According to claim 1, a dynamic characteristics simulation optimization method of a highly sensitive piezoresistive flexible strain sensor is characterized in that: The material-related information in step 2 specifically includes mechanical properties and electrical properties; The constitutive equation of the mechanical properties of the material adopts the third-order Mooney-Rivlin model: W=C 10 (I1-3)+C 01 (I2-3)+C 20 (I1-3) 2 Where W is the strain energy density, I1 and I2 are the principal moments of inertia, and C 10 , C 01 , C 20 is a constant; The resistivity-strain relationship model of the electrical characteristics adopts the Kraus model: Among them, ρ is the dynamic resistivity during stretching, ρ0 is the initial resistivity, m, ε c are constants related to fractal and yield strain respectively.

3. The method for simulating and optimizing the dynamic characteristics of a highly sensitive piezoresistive flexible strain sensor according to claim 1 is characterized in that: In step 3, the positions of the corresponding nodes of the contact interface between the conductive part and the non-conductive part are kept consistent, and then the nummrg command is used to merge the finite element model nodes of the conductive part and the non-conductive part.

4. The method for simulating and optimizing the dynamic characteristics of a highly sensitive piezoresistive flexible strain sensor according to claim 1, characterized in that: When performing simulation analysis in step 4, a *do loop is used for iterative calculation; the electrical simulation is used as the main program, and the statics simulation is used as a subroutine. During each iteration, when performing statics simulation, the etable command is used to extract the strain of each unit of the conductive part (1) obtained by the statics analysis; and the *get command is used to save it to the array parameter; Use parsav to save all parameters. When performing electrical simulation, use the upgeom command to update the node coordinates of the sensor finite element model and update the resistivity of each unit of the conductive part (1) based on the Kraus model. Both statics and electricity are solved using the preconditioned conjugate gradient iterative solver PCG.

5. The method for simulating and optimizing the dynamic characteristics of a highly sensitive piezoresistive flexible strain sensor according to claim 1, characterized in that: In step 4, a voltage value at both ends of the sensor is obtained by applying a 0 potential to one end node of the sensor and a 1A current load to the other end node, and the voltage value is equivalent to a resistance value according to Ohm's law.

6. The method for simulating and optimizing the dynamic characteristics of a highly sensitive piezoresistive flexible strain sensor according to claim 5, characterized in that: Among the end face nodes to which current load is applied, the 1A current load is distributed among the edge vertex nodes, edge non-vertex nodes, and non-edge nodes in a ratio of 4:2:1.

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