A flexible tactile sensor based on zero poisson's ratio structure and a preparation method thereof

Abstract

The application discloses a flexible tactile sensor based on a zero Poisson's ratio structure and a preparation method thereof. The structure comprises a substrate layer and a sensing layer on the substrate layer. The sensing layer comprises a plurality of rows of transverse sensing functional unit groups and a plurality of rows of longitudinal sensing functional unit groups. A row of longitudinal sensing functional unit groups is arranged between two adjacent rows of transverse sensing functional unit groups. The transverse sensing functional unit group is composed of a plurality of equidistantly distributed transverse sensing functional units. The longitudinal sensing functional unit group is composed of a plurality of equidistantly distributed longitudinal sensing functional units. A star-shaped structure is arranged between two longitudinally adjacent transverse sensing functional units and two transversely adjacent longitudinal sensing functional units. The flexible tactile sensor is designed to have a Poisson's ratio close to 0, so that the size of the biaxial strain can be recognized without interference, the direction and size of the shear force can be accurately recognized, and the sensing sensitivity of the device to the biaxial strain is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible tactile sensor, in particular to a flexible tactile sensor based on zero poisson's ratio structure and a preparation method thereof. BACKGROUND

[0002] With the rapid development of intelligent robots, the important role of tactile sensor in the intelligent control of robots is increasingly prominent. Similar to the tactile perception ability of human skin, tactile sensor enables robots to perceive the shape, hardness, texture and sliding during manipulation of objects, which cannot be achieved by other methods such as machine vision. In order to simulate the comprehensive tactile perception ability and mechanical properties of human skin, a large number of studies have been conducted on the development of electronic skin. Unlike traditional sensors based on rigid materials and structures, flexible tactile sensors mainly consist of a flexible substrate layer and a sensing functional layer, which can convert mechanical stimuli into electrical signals. At present, people have also proposed many electronic skin devices based on various sensing mechanisms, such as capacitance, piezoresistance, piezoelectricity, etc.

[0003] Compared with traditional sensing materials, metamaterials have extraordinary advantages in static modulus, density, energy absorption and dissipation, acoustics, and thermal conductivity, etc. Among them, the negative poisson's ratio material is a typical mechanical metamaterial, which will expand longitudinally when stretched transversely. Compared with ordinary sensors, the sensor based on negative poisson's ratio can produce greater deformation under the same pressure, and has higher sensitivity. In addition to negative poisson's ratio materials, 0 poisson's ratio materials also have superior performance, which have almost 0 longitudinal deformation when stretched transversely, that is, in the case of a large transverse strain, the longitudinal strain is almost 0. Therefore, 0 poisson's ratio materials can independently perceive bidirectional strain without interference. SUMMARY

[0004] The purpose of the present application is to provide a flexible tactile sensor based on zero poisson's ratio structure and a preparation method thereof.

[0005] The technical scheme of the present application is as follows:

[0006] A flexible tactile sensor based on zero poisson's ratio structure, comprising a substrate layer and a sensing layer located on the substrate layer, the sensing layer comprising a plurality of rows of transverse sensing functional unit groups and a plurality of rows of longitudinal sensing functional unit groups, one row of longitudinal sensing functional unit groups being arranged between two adjacent rows of transverse sensing functional unit groups, the transverse sensing functional unit group being composed of a plurality of equidistantly distributed transverse sensing functional units, the longitudinal sensing functional unit group being composed of a plurality of equidistantly distributed longitudinal sensing functional units, and a star-shaped structure being arranged between two longitudinally adjacent transverse sensing functional units and two transversely adjacent longitudinal sensing functional units.

[0007] The substrate layer is prepared from a flexible material.

[0008] The thickness of the base layer is 0.2-1mm.

[0009] The transverse sensing functional unit is composed of a plurality of longitudinal sensing functional modules connected side by side, and the longitudinal sensing functional unit is composed of a plurality of transverse sensing functional modules connected side by side.

[0010] The transverse sensing functional unit and the longitudinal sensing functional unit are both in a wave shape, and the longitudinal sensing functional module and the transverse sensing functional module are both composed of an island-bridge structure and a conductive layer, and the conductive layer is located on the island-bridge structure.

[0011] The conductive layer is made of metal conductive material or composite conductive material.

[0012] The preparation method of the flexible tactile sensor based on the zero Poisson's ratio structure includes the following steps:

[0013] S1, a base mold and a mask plate are prepared, and a wave-shaped structure corresponding to the island-bridge structure of the transverse sensing functional unit and the longitudinal sensing functional unit is engraved on the base mold, and the mask plate is cut into a mold A with a star-shaped hollow part and a mold B retaining a star-shaped structure part;

[0014] S2, align the mold A and the base mold, and then put the mold B into the star-shaped hollow part of the mold A;

[0015] S3, remove the mold A;

[0016] S4, inject the liquid flexible material solution into the base mold to make it uniformly distributed in the base mold;

[0017] S5, solidify the flexible material solution in the base mold by heating and drying, and then peel off from the base mold to obtain a base with island-bridge structure and star-shaped structure;

[0018] S6, deposit the conductive material on the island-bridge structure to form a conductive layer, and obtain a flexible tactile sensor based on a zero Poisson's ratio structure.

[0019] The materials of the base mold and the mask plate are both acrylic plates, the thickness of the base mold is 5mm, and the thickness of the mask plate is 0.2-1mm.

[0020] Compared with the prior art, the application has the beneficial effects that the flexible tactile sensor based on the zero Poisson's ratio structure is prepared by using a flexible material for a base layer, is easy to deform, can be attached to the surface of a robot, and through structural design, the Poisson's ratio of the device is close to 0, so that the size of the biaxial strain can be recognized without interference, so that the direction and size of the shear force can be accurately recognized, and the wave-shaped structure composed of island-bridge structures is arranged in the sensing area of the flexible base, so that under the action of the same external force, the conductive material can have greater resistance change, so that the sensing sensitivity of the device to the biaxial strain is improved. The flexible tactile sensor has simple structure, can be made into sensors of different sizes according to actual needs, is easy to manufacture, and is conducive to popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 The structure diagram of the flexible tactile sensor based on the zero Poisson's ratio structure provided by the present application is shown in the figure.

[0023] Figure 2 The preparation method flow chart of the flexible tactile sensor based on the zero Poisson's ratio structure provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0025] Please refer to Figure 1The application provides a flexible tactile sensor based on a zero Poisson's ratio structure, which comprises a substrate layer 1 and a sensing layer 2 on the substrate layer 1. The substrate layer 1 is prepared from a flexible material, such as polydimethylsiloxane, Ecoflex or the like, and has a thickness of 0.2-1 mm; the sensing layer 2 comprises a plurality of rows of transverse sensing functional unit groups 3 and a plurality of rows of longitudinal sensing functional unit groups 4, one row of longitudinal sensing functional unit groups 4 is arranged between any two adjacent rows of transverse sensing functional unit groups 3, the transverse sensing functional unit group 3 is composed of a plurality of equidistantly distributed wave-shaped transverse sensing functional units, the transverse sensing functional unit is composed of a plurality of side-by-side connected longitudinal sensing functional modules, the longitudinal sensing functional unit group 4 is composed of a plurality of equidistantly distributed wave-shaped longitudinal sensing functional units, and the longitudinal sensing functional unit is composed of a plurality of side-by-side connected transverse sensing functional modules, wherein the longitudinal sensing functional module and the transverse sensing functional module are both composed of an island-bridge structure 5 and a conductive layer 6, the conductive layer 6 is located on the island-bridge structure 5, the conductive layer 6 is a metal conductive material or a composite conductive material, and star-shaped structures are arranged between longitudinally adjacent two transverse sensing functional units and transversely adjacent two longitudinal sensing functional units.

[0026] The preparation method of the above-mentioned flexible tactile sensor based on a zero Poisson's ratio structure comprises the following steps as shown in the figure: Figure 2

[0027] S1. Taking an acrylic plate as a basic material, a wave-shaped structure corresponding to the island-bridge structure of the transverse sensing functional unit and the longitudinal sensing functional unit is engraved on a substrate mold 9 by using a laser cutting machine, the thickness of the substrate mold 9 is 5 mm, and meanwhile, a mask plate (an acrylic plate) is cut by using the laser cutting machine to obtain a mold A 8 with a star-shaped hollow part and a mold B 7 retaining a star-shaped structure part, and the thickness of the acrylic plate is 0.2-1 mm;

[0028] S2. The mold A 8 and the substrate mold 9 are aligned, and then the mold B 7 is placed into the star-shaped hollow part of the mold A 8, so as to complete the positioning and fixing of the mold B 7 on the substrate mold 9;

[0029] S3. The mold A 8 is removed, and the mold B 7 and the substrate mold 9 are left;

[0030] S4. A liquid flexible material solution 10 is injected into the substrate mold 9, and is uniformly distributed in the substrate mold 9 by means of spin coating;

[0031] S5. The substrate mold 11 filled with the flexible material solution is dried by heating, so that the flexible material solution in the substrate mold 9 is solidified, and then the substrate mold 9 is peeled off to obtain a substrate 12 with an island-bridge structure and a star-shaped structure;

[0032] ​S6, depositing a metal conductive material or a composite conductive material on the island-bridge structure to form a conductive layer, to obtain a flexible tactile sensor 13 based on a zero Poisson's ratio structure.

[0033] In order to illustrate the preparation method of the present application, the following is illustrated by specific examples.

[0034] Example 1

[0035] The present embodiment provides a preparation method of a flexible tactile sensor based on a zero Poisson's ratio structure, comprising the following steps:

[0036] S1, using an acrylic plate as a base material, using a laser cutting machine to carve a wave-shaped structure corresponding to the island-bridge structure of the transverse sensing functional unit and the longitudinal sensing functional unit on a base mold, the thickness of the base mold is 5mm, and at the same time, using a laser cutting machine to cut a mask plate (acrylic plate) to obtain a mold A with a star-shaped hollow part and a mold B retaining a star-shaped structure part, the thickness of the acrylic plate is 0.2-1mm;

[0037] S2, aligning the mold A and the base mold, and then placing the mold B into the star-shaped hollow part of the mold A to complete the positioning and fixing of the mold B on the base mold;

[0038] S3, removing the mold A, leaving the mold B and the base mold;

[0039] S4, uniformly mixing polydimethylsiloxane prepolymer and crosslinking agent in a mass ratio of 10:1, using vacuum extraction to make the bubbles in the mixed liquid float to the surface and break, preparing liquid polydimethylsiloxane, and injecting it into the base mold, and uniformly distributing it in the base mold by spin coating, the speed of spin coating is 450r / min, and the spin coating time is 30s;

[0040] S5, placing the base mold filled with liquid polydimethylsiloxane into an oven at 80℃ for constant temperature heating for about 2 hours to obtain a solidified base with 0 Poisson's ratio;

[0041] S6, using laser cutting to process a mask that only exposes the base sensing functional unit area, the mask material is PET with a thickness of 0.2mm, and the mask plate is placed on the base with 0 Poisson's ratio structure prepared above;

[0042] S7, using a magnetron sputtering process to plate gold on the base with an island-bridge structure, selecting a circular cake target with a diameter of 50mm and a thickness of 2mm, the sputtering environment is pure argon gas with a pressure of 1Pa, the sputtering power is 80W, the thickness is 50nm, and the mask is removed after sputtering is completed.

[0043] Thus, a flexible tactile sensor based on a zero Poisson's ratio structure is prepared.

[0044] Embodiment 2

[0045] The embodiment provides a preparation method of a flexible tactile sensor based on a zero Poisson's ratio structure, and comprises the following steps:

[0046] S1, taking an acrylic plate as a basic material, using a laser cutting machine to carve a wave-shaped structure corresponding to island-bridge structures of the transverse sensing functional unit and the longitudinal sensing functional unit on a base mold, the thickness of the base mold is 5 mm, and a mask plate (an acrylic plate) is cut by using the laser cutting machine to obtain a mold A with a star-shaped hollow part and a mold B retaining a star-shaped structure part, the thickness of the acrylic plate is 0.2-1 mm;

[0047] S2, aligning the mold A and the base mold, and then placing the mold B into the star-shaped hollow part of the mold A, so that the positioning and fixing of the mold B on the base mold are completed;

[0048] S3, removing the mold A, and leaving the mold B and the base mold;

[0049] S4, uniformly mixing A component and B component of Ecoflex at a mass ratio of 1:1, using a vacuum pumping mode to make air bubbles in the mixed liquid float to the surface and break, preparing liquid Ecoflex, and injecting the liquid Ecoflex into the base mold, and uniformly distributing the liquid Ecoflex in the base mold by spin coating, the speed of spin coating is 450 r / min, and the spin coating time is 30 s;

[0050] S5, placing the base mold filled with the Ecoflex into a 60 DEG C oven for constant temperature heating for about 2 hours, so as to obtain a solidified base with a 0 Poisson's ratio;

[0051] S6, using laser cutting to process a mask plate for exposing only the base sensing functional unit region, the mask material is PET, and the thickness is 0.2 mm, and the mask plate is placed on the base with the 0 Poisson's ratio structure prepared above;

[0052] S7, adopting a magnetron sputtering process to plate gold on the base with the island-bridge structure, selecting a circular cake target material with a diameter of 50 mm and a thickness of 2 mm, the sputtering environment is pure argon, the pressure is 1 Pa, the sputtering power is 80 W, the thickness is 50 nm, and the mask plate is removed after sputtering is completed.

[0053] Thus, the preparation of the flexible tactile sensor based on the zero Poisson's ratio structure is completed.

[0054] Embodiment 3

[0055] The embodiment provides a preparation method of a flexible tactile sensor based on a zero Poisson's ratio structure, and comprises the following steps:

[0056] S1, taking acrylic plate as a basic material, using a laser cutting machine to carve a wave-shaped structure corresponding to the island-bridge structure of the transverse sensing function unit and the longitudinal sensing function unit on a base mold, the thickness of the base mold is 5mm, and a mask plate (acrylic plate) is cut by using the laser cutting machine to obtain a mold A with a star-shaped hollow part and a mold B retaining a star-shaped structure part, the thickness of the acrylic plate is 0.2-1mm;

[0057] S2, aligning the mold A and the base mold, and then placing the mold B into the star-shaped hollow part of the mold A to complete the positioning and fixing of the mold B on the base mold;

[0058] S3, removing the mold A, and leaving the mold B and the base mold;

[0059] S4, uniformly mixing dimethylsiloxane prepolymer and a crosslinking agent in a mass ratio of 10:1, using vacuum extraction to make the bubbles in the mixed solution float to the surface and break, preparing liquid dimethylsiloxane, and injecting the liquid dimethylsiloxane into the base mold, and uniformly distributing the liquid dimethylsiloxane in the base mold by spin coating, the speed of spin coating is 450r / min, and the spin coating time is 30s;

[0060] S5, placing the base mold filled with liquid dimethylsiloxane into an oven at 80°C for constant heating for about 2 hours to obtain a solidified base with an island-bridge structure;

[0061] S6, using laser cutting to process a mask plate that only exposes the base sensing function unit region, the mask material is PET, and the thickness is 0.2mm, and the mask plate is placed on the base with the 0 poisson's ratio structure prepared above;

[0062] S7, placing the silver nanowire / ethanol solution into a spray pen, adjusting the height of the spray pen, the temperature of the heating plate and the gas flow, and spraying the silver nanowire dispersion liquid on the base with the island-bridge structure covered with the mask plate;

[0063] S8, annealing the flexible tactile sensor obtained in the above step in an oven at 120°C for 8 hours.

[0064] Thus, the preparation of the flexible tactile sensor based on the zero poisson's ratio structure is completed.

[0065] The above is only a preferred embodiment of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A flexible tactile sensor based on a zero-Poisson ratio structure, characterized by: The sensor layer comprises a plurality of rows of transverse sensing functional unit groups and a plurality of rows of longitudinal sensing functional unit groups, and a row of longitudinal sensing functional unit groups is arranged between two adjacent rows of transverse sensing functional unit groups, the transverse sensing functional unit group is composed of a plurality of equidistantly distributed transverse sensing functional units, the longitudinal sensing functional unit group is composed of a plurality of equidistantly distributed longitudinal sensing functional units, and a star structure is arranged between two transversely adjacent transverse sensing functional units and two longitudinally adjacent longitudinal sensing functional units.

2. The flexible tactile sensor based on zero-Poisson's ratio structure according to claim 1, characterized in that: The substrate layer is made of a flexible material. 3.The flexible tactile sensor based on zero-Poisson’s ratio structure of claim 1, wherein: The thickness of the substrate layer is 0.2-1 mm.

4. The flexible tactile sensor based on zero-Poisson-ratio structure of claim 1, wherein: The transverse sensing functional unit is composed of a plurality of longitudinally arranged longitudinal sensing functional modules, and the longitudinal sensing functional unit is composed of a plurality of laterally arranged transverse sensing functional modules.

5. The flexible tactile sensor based on zero-Poisson-ratio structure according to claim 4, characterized in that: The transverse sensing functional unit and the longitudinal sensing functional unit are both in a wave shape, the longitudinal sensing functional module and the transverse sensing functional module are both composed of an island-bridge structure and a conductive layer, and the conductive layer is arranged on the island-bridge structure.

6. The flexible tactile sensor based on zero-Poisson-ratio structure according to claim 5, characterized in that: The conductive layer is made of a metal conductive material or a composite conductive material.

7. The method of claim 5, wherein the method further comprises: The method comprises the following steps: S1, preparing a substrate mold and a mask plate, engraving a wave-shaped structure corresponding to the island-bridge structure of the transverse sensing functional unit and the longitudinal sensing functional unit on the substrate mold, and cutting the mask plate into a mold A having a star-shaped hollow part and a mold B retaining a star-shaped structure part; S2, aligning the mold A and the substrate mold, and then placing the mold B into the star-shaped hollow part of the mold A; S3, removing the mold A; S4, injecting a liquid flexible material solution into the substrate mold to make it uniformly distributed in the substrate mold; S5, solidifying the flexible material solution in the substrate mold by heating and drying, and then peeling off from the substrate mold to obtain a substrate with an island-bridge structure and a star structure; S6, depositing a conductive material on the island-bridge structure to form a conductive layer, and obtaining a flexible tactile sensor based on a zero Poisson's ratio structure.

8. The method of claim 7, wherein the method further comprises: The materials of the substrate mold and the mask plate are both acrylic plates, the thickness of the substrate mold is 5 mm, and the thickness of the mask plate is 0.2-1 mm.

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