A stretchable pressure sensitive material and its preparation method and application

Abstract

The application discloses a stretchable pressure sensitive material, which comprises an elastomer and a conductive filler, the elastomer is provided with an array of vertical holes, the conductive filler is filled in the array of vertical holes, and the cross-sectional shape of the elastomer is selected from one of a trapezoidal shape, a rectangular shape and a trapezoidal-like shape; and the application further provides a preparation method and application of the stretchable pressure sensitive material; compared with the prior art, the stretchable pressure sensitive material is made of the elastomer and the conductive filler, the sensor can realize a 50% tensile strain due to the fact that the elastomer and the conductive filler are both based on stretchable elastic materials; the conductive filler / hole is designed into a unique three-dimensional structure, and the hardness of the conductive filler is higher than that of the porous array elastomer; therefore, the stretchable pressure sensitive material has high stability of resistance under the condition of stretching, and the resistance change is less than 0.5% under a 20% tensile strain.

Description

Technical Field

[0001] This invention belongs to the field of flexible materials technology, specifically relating to a stretchable pressure-sensitive material, its preparation method, and its application. Background Technology

[0002] Stretchable pressure-sensitive materials are a core material for pressure sensors and a hot research topic. Compared with traditional rigid pressure-sensitive materials, stretchable pressure-sensitive materials have the advantages of being soft and comfortable and having strong deformation capabilities, which can provide better comfort and wearability for pressure sensors.

[0003] During the stretching process, due to the Poisson effect of the material, the stretchable pressure sensor experiences compressive strain perpendicular to the stretching direction, causing a significant change in the sensor's resistance with tensile deformation. Furthermore, the sensitivity of the stretchable pressure sensor also changes significantly under tension, increasing by 100% at 50% strain.

[0004] Currently, to achieve strain stability in stretchable pressure sensors, strategies exist to improve strain stability by constructing pyramidal, cylindrical, and prismatic structures on the surface of the pressure-sensitive material, based on structural design to release strain. However, the strain stability of stretchable pressure sensors fabricated based on different structural designs varies greatly, and the influence of structural parameters on strain stability is poorly explored. Furthermore, most current stretchable pressure sensors are fabricated using template methods, making it difficult to explore the regularity of three-dimensional structural parameters. Summary of the Invention

[0005] The purpose of this invention is to provide a stretchable pressure-sensitive material that exhibits small resistance change under tensile conditions, high sensitivity and good stability under pressure conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a stretchable pressure-sensitive material, comprising an elastomer and a conductive filler, wherein an array of vertical holes are constructed on the elastomer, and the conductive filler is filled in the array of vertical holes, and the cross-sectional shape of the elastomer is selected from one of trapezoidal, rectangular, and trapezoidal shapes.

[0007] This invention designs a force-sensitive material with a three-dimensional array-type hole structure. When the sensor is stretched, the porous array elastomer matrix undergoes large in-plane deformation, which can protect the conductive functional material from the interference of tensile strain, thereby achieving high tensile stability of the stretchable sensor. Furthermore, the geometry of the holes (elastomer) is described by three parameter variables: the ratio of top to bottom length, the side curvature, and the number of edges, which makes it easy to obtain different three-dimensional structures by setting parameter values.

[0008] Preferably, the material of the elastomer is selected from one or more of the following: acrylate, polyurethane acrylate, aliphatic aromatic random copolyester, polydimethylsiloxane, methacryloxypropylmethylsiloxane-dimethylsiloxane, silicone, rubber, resin, hydrogel, polyurethane, styrene block copolymer, polyvinyl chloride, polyimide, polyterephthalic acid plastics, polyethylene octene coelastomer, and thermoplastic elastomer.

[0009] Preferably, the cross-sectional shape of the elastomer is rectangular. The cross-sectional shape of the elastomer is arranged in a square pattern, with the spacing described by an array density parameter variable, which facilitates obtaining array hole structures with different densities by setting the parameter value.

[0010] Preferably, the conductive filler comprises a conductive material and an elastic material, and the mass ratio of the conductive material to the elastic material is 0.001-1:1.

[0011] Preferably, the conductive material is selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, single-layer graphene powder, carbon black powder, iron powder, nickel powder, silver-plated nickel powder, and nickel-plated graphene powder.

[0012] Preferably, the elastic material is selected from one or more of the following: acrylate, polyurethane acrylate, aliphatic aromatic random copolyester, polydimethylsiloxane, methacryloxypropylmethylsiloxane-dimethylsiloxane, silicone, rubber, resin, hydrogel, polyurethane, styrene block copolymer, polyvinyl chloride, polyimide, polyterephthalic acid plastics, polyethylene octene coelastomer, and thermoplastic elastomer.

[0013] The second objective of this invention is to provide a method for preparing a stretchable pressure-sensitive material, the method specifically comprising the following steps:

[0014] S1. Model Design: The array-shaped hole structure of the elastomer is designed using modeling software. An array of vertical holes is constructed on the elastomer. The ratio of the top and bottom lengths of the hole structure, the side curvature and the number of edges are specified, and the array density is specified. The difference between the array density and the elastomer is taken to obtain the design model.

[0015] S2. Elastomer preparation: The elastomer is prepared by using 3D printing to fabricate the model designed in step S1.

[0016] S3. Preparation of conductive filler: Conductive filler is obtained by combining conductive material with elastic material;

[0017] S4. Filling and curing: The conductive filler obtained in step S3 is injected into the pores of the elastomer obtained in step S2, and after curing, a stretchable pressure-sensitive material is obtained.

[0018] Preferably, in step S4, the curing conditions are as follows: curing temperature is 60-100℃, and curing time is 0.5-2h.

[0019] A third objective of this invention is to provide an application of a stretchable pressure-sensitive material in a stretchable pressure sensor.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. This invention utilizes elastomers and conductive fillers to create stretchable pressure-sensitive materials. Since both the elastomers and conductive fillers are based on stretchable elastic materials, the sensor can achieve 50% tensile strain.

[0022] 2. The present invention designs the conductive filler / pores into a unique three-dimensional structure, and the hardness of the conductive filler is higher than that of the porous array elastomer. Therefore, the stretchable pressure-sensitive material of the present invention has high resistance stability under tensile conditions, and the resistance change is less than 0.5% under 20% tensile strain.

[0023] 3. The present invention uses structural design optimization to obtain a pressure-sensitive material, which has high sensitivity to pressure;

[0024] 4. The preparation method of the stretchable pressure-sensitive material provided by the present invention has a simple process, is easy to apply and promote, and can realize the mass production of porous array elastomers through 3D printing technology. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the stretchable pressure-sensitive material in Embodiment 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the stretchable pressure-sensitive material in Embodiment 2 of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of the stretchable pressure-sensitive material in Embodiment 3 of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the stretchable pressure-sensitive material in Embodiment 4 of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of the stretchable pressure-sensitive material in Embodiment 5 of the present invention;

[0030] Figure 6 This is the relationship curve of the resistivity change rate with tensile deformation of the stretchable pressure-sensitive material prepared in Examples 1-5 of the present invention under tensile strain of 0-300%.

[0031] Figure 7This is the relationship curve of the resistivity change rate with compressive stress of the stretchable pressure-sensitive material prepared in Examples 1-5 of the present invention under compressive stress of 0-2 kPa.

[0032] Figure 8 This is a scatter plot of the ratio of pressure sensitivity to strain sensitivity of the stretchable sensitive material prepared in Examples 1-5 of this invention.

[0033] Figure label:

[0034] 1-Elastomer, 2-Conductive filler. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0036] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0038] This invention provides a stretchable pressure-sensitive material, including an elastomer 1 and a conductive filler 2. The elastomer 1 has an array of vertical holes, and the conductive filler 2 is filled in the array of vertical holes. The cross-sectional shape of the elastomer 1 is selected from one of trapezoidal, rectangular, and trapezoidal shapes.

[0039] This invention designs a force-sensitive material with a three-dimensional array-type hole structure. When the sensor is stretched, the matrix of the porous array elastic body 1 undergoes large in-plane deformation, which can protect the conductive functional material from the interference of tensile strain, thereby achieving high tensile stability of the stretchable sensor. Moreover, the geometry of the holes (elastic body 1) is described by three parameter variables: the ratio of top to bottom length, the side curvature, and the number of edges, which makes it easy to obtain different three-dimensional structures by setting parameter values.

[0040] In a specific embodiment of the present invention, the material of elastomer 1 may be selected from one or more of the following: acrylate, polyurethane acrylate, aliphatic aromatic random copolyester, polydimethylsiloxane, methacryloxypropylmethylsiloxane-dimethylsiloxane, silicone, rubber, resin, hydrogel, polyurethane, styrene block copolymer, polyvinyl chloride, polyimide, polyterephthalic acid plastics, polyethylene octene coelastomer, and thermoplastic elastomer.

[0041] In a specific embodiment of the present invention, the cross-sectional shape of the elastic body 1 is rectangular. The cross-sectional shape of the elastic body 1 is arranged in a square pattern, and the spacing between them is described by an array density parameter variable, which facilitates obtaining array hole structures with different densities by setting the parameter value.

[0042] Preferably, the conductive filler 2 comprises a conductive material and an elastic material, and the mass ratio of the conductive material to the elastic material is 0.001-1:1. The conductive material is selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, single-layer graphene powder, carbon black powder, iron powder, nickel powder, silver-plated nickel powder, and nickel-plated graphene powder; the elastic material is selected from one or more of acrylates, polyurethane acrylates, aliphatic aromatic random copolyesters, polydimethylsiloxane, methacryloxypropylmethylsiloxane-dimethylsiloxane, silicone, rubber, resin, hydrogel, polyurethane, styrene block copolymers, polyvinyl chloride, polyimide, polyterephthalic acid plastics, polyethylene octene coelastomers, and thermoplastic elastomers.

[0043] This invention also provides a method for preparing a stretchable pressure-sensitive material, specifically including the following steps:

[0044] S1. Model Design: The array-shaped hole structure of the elastic body 1 is designed using modeling software. An array-shaped vertical hole structure is constructed on the elastic body 1. The ratio of the top and bottom lengths of the hole structure, the side curvature and the number of edges are specified, and the array density is specified. The difference between the array density and the elastic body 1 is used to obtain the design model.

[0045] S2, Preparation of Elastomer 1: Elastomer 1 is prepared by using 3D printing to fabricate the model designed in step S1;

[0046] S3. Preparation of conductive filler 2: The conductive material is combined with the elastic material to obtain conductive filler 2;

[0047] S4. Filling and curing: The conductive filler 2 obtained in step S3 is injected into the pores of the elastomer 1 obtained in step S2, and cured at a temperature of 60-100℃ for 0.5-2 hours to obtain a stretchable pressure-sensitive material.

[0048] This invention also provides the application of stretchable pressure-sensitive materials in stretchable pressure sensors.

[0049] The technical effects of the present invention will be described below with reference to specific embodiments.

[0050] Example 1

[0051] like Figure 1 As shown, this embodiment provides a stretchable pressure-sensitive material, including an elastomer 1 and a conductive filler 2. The material of the elastomer 1 is a rubber-like photosensitive resin (Agilus 30), and the conductive filler 2 is a composite of nickel-plated graphite powder and a rubber-like photosensitive resin (Formlabs 50A) in a mass ratio of 1:1. An array of vertical holes is constructed on the elastomer 1. The hole structure and array spacing are specified by the ratio of top to bottom length, side curvature, number of edges, and array density. The conductive filler 2 fills the holes in the elastomer 1.

[0052] This embodiment also provides a method for preparing the above-mentioned stretchable pressure-sensitive material, including the following steps:

[0053] S1. Model Design: The array-shaped hole structure of the elastomer 1 is designed using modeling software. An array-shaped hole structure is constructed in the middle of the 80mm×20mm×2mm rectangular elastomer 1. The bottom side length of the hole structure is specified as 1mm, the ratio of the top to the bottom length is 0.5, the side curvature is 0, the number of edges is Inf (i.e., a 360° rotating body), and the array density is specified as 3×3, i.e., the center-to-center spacing of the holes is 6mm. The design model is obtained by taking the difference between the array-shaped hole structure and the rectangular elastomer 1.

[0054] S2, Preparation of Elastomer 1: The model design in step S1 is printed using a 3D printer to obtain elastomer 1;

[0055] S3, Preparation of conductive filler 2: Nickel-plated graphite powder and rubber-like photosensitive resin (Formlabs50A) are compounded at a mass ratio of 1:1 to obtain conductive filler 2;

[0056] S4. Filling and curing: Inject the conductive filler 2 from step S3 into the holes of the elastomer 1 printed in step S2, and cure at 60°C for 0.5 hours to obtain a stretchable pressure-sensitive material.

[0057] Example 2

[0058] The only difference from Example 1 is that the structure of the stretchable pressure-sensitive material in this example is as follows: Figure 2 As shown, the ratio of the top to the bottom length of the hole structure is 1, and the rest is the same as in Example 1, so it will not be repeated here.

[0059] Example 3

[0060] The only difference from Example 1 is that the structure of the stretchable pressure-sensitive material in this example is as follows: Figure 3As shown, the lateral curvature is 752.94m. -1 Everything else is the same as in Example 1, and will not be repeated here.

[0061] Example 4

[0062] The only difference from Example 1 is that the structure of the stretchable pressure-sensitive material in this example is as follows: Figure 4 As shown, the number of edges is 4, and the rest is the same as in Example 1, so it will not be repeated here.

[0063] Example 5

[0064] The only difference from Example 1 is that the structure of the stretchable pressure-sensitive material in this example is as follows: Figure 5 As shown, the array density is 5×5, that is, the center-to-center spacing of the holes is 3mm. The rest is the same as in Example 1, and will not be repeated here.

[0065] Example 6

[0066] The only difference from Example 1 is that the conductive filler 2 in this example is a composite of nickel-plated graphite powder and methacryloxypropylmethylsiloxane-dimethylsiloxane (p-PDMS) in a mass ratio of 1:1. The rest is the same as in Example 1 and will not be repeated here.

[0067] Example 7

[0068] The only difference from Example 6 is that the conductive filler 2 in this example is a composite of nickel-plated graphite powder and methacryloxypropylmethylsiloxane-dimethylsiloxane (p-PDMS) in a mass ratio of 0.001:1. The rest is the same as in Example 1, and will not be repeated here.

[0069] Example 8

[0070] The only difference from Example 1 is that the conductive filler 2 in this example is a composite of silver-plated nickel powder and rubber-like photosensitive resin (Formlabs50A) in a mass ratio of 1:1. Everything else is the same as in Example 1, and will not be repeated here.

[0071] Example 9

[0072] The only difference from Example 8 is that the conductive filler 2 in this example is a composite of silver-plated nickel powder and rubber-like photosensitive resin (Formlabs50A) in a mass ratio of 0.1:1. The rest is the same as in Example 1, and will not be repeated here.

[0073] The performance of the stretchable pressure-sensitive materials prepared in Examples 1-5 of this invention was tested, and the test results are as follows: Figures 6-8 As shown, from Figures 6-8As can be seen, this invention utilizes a porous array elastomer 1 and a conductive functional material to fabricate a stretchable pressure-sensitive material. Since both the porous array elastomer 1 and the conductive functional material are based on stretchable elastic materials, the sensor can achieve a tensile strain of 50%. This invention designs the conductive functional material / pores into a unique three-dimensional structure, and the hardness of the conductive functional material is higher than that of the porous array elastomer 1. Therefore, the stretchable pressure-sensitive material of this invention has high resistance stability under tensile conditions, with a resistance change of less than 0.5% under a tensile strain of 20%.

[0074] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A stretchable pressure-sensitive material, characterized in that, The device includes an elastomer (1) and a conductive filler (2). The elastomer (1) has an array of vertical pores. The conductive filler (2) fills the array of vertical pores. The cross-sectional shape of the elastomer (1) is selected from one of trapezoidal, rectangular, and trapezoidal shapes. The conductive filler (2) includes a conductive material and an elastic material, and the mass ratio of the conductive material to the elastic material is 0.001-1:

1. The conductive material is selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, single-layer graphene powder, carbon black powder, iron powder, nickel powder, silver-plated nickel powder, and nickel-plated graphene powder. The elastic material is selected from one or more of acrylate, polyurethane acrylate, aliphatic aromatic random copolyester, polydimethylsiloxane, methacryloxypropylmethylsiloxane-dimethylsiloxane, polyurethane, styrene block copolymer, polyvinyl chloride, polyimide, polyterephthalic acid plastics, and polyethylene octene co-elastomer.

2. The stretchable pressure-sensitive material as described in claim 1, characterized in that, The material of the elastomer (1) is selected from one or more of the following: acrylate, polyurethane acrylate, aliphatic aromatic random copolyester, polydimethylsiloxane, methacryloyloxypropylmethylsiloxane-dimethylsiloxane, polyurethane, styrene block copolymer, polyvinyl chloride, polyimide, polyterephthalic acid plastics, and polyethylene octene co-elastomer.

3. The stretchable pressure-sensitive material as described in claim 1, characterized in that, The cross-sectional shape of the elastomer (1) is rectangular.

4. A method for preparing a stretchable pressure-sensitive material as described in any one of claims 1-3, characterized in that, The preparation method specifically includes the following steps: S1. Model design: The array-shaped hole structure of the elastomer (1) is designed using modeling software. An array-shaped vertical hole structure is constructed on the elastomer (1). The ratio of the top and bottom lengths of the hole structure, the side curvature and the number of edges are specified, and the array density is specified. The difference set between the array and the elastomer (1) is used to obtain the design model. S2, Elastomer (1) preparation: Elastomer (1) was prepared by using 3D printing method based on the model design in step S1; S3. Preparation of conductive filler (2): The conductive material is combined with the elastic material to obtain conductive filler (2); S4. Filling and curing: The conductive filler (2) obtained in step S3 is injected into the pores of the elastomer (1) obtained in step S2, and after curing, a stretchable pressure-sensitive material is obtained.

5. The method for preparing the stretchable pressure-sensitive material as described in claim 4, characterized in that, In step S4, the curing conditions are as follows: curing temperature is 60-100℃, and curing time is 0.5-2h.

6. The application of a stretchable pressure-sensitive material as described in any one of claims 1-3 in a stretchable pressure sensor.

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