CN111044181B

CN111044181B - Gradient zero Poisson ratio structure capacitive flexible touch sensor and preparation method thereof

Info

Publication number: CN111044181B
Application number: CN201911314128.4A
Authority: CN
Inventors: 刘旺玉; 郭正强; 谢卫规; 苟竞仁
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2021-10-26
Anticipated expiration: 2039-12-19
Also published as: CN111044181A

Abstract

The invention discloses a gradient zero-Poisson ratio structure capacitive flexible touch sensor, which comprises an insulating surface bulge, an insulating film and a substrate film, wherein the insulating surface bulge is in contact with an external object; the bottom of the insulating surface bulge is provided with an insulating film, a dielectric layer with a gradient zero Poisson ratio structure is arranged between the insulating film and the substrate film, the dielectric layer is in direct contact with the insulating film and the substrate film respectively, the lower surface of the insulating film is provided with an upper-layer flexible electrode, and the upper surface of the substrate film is provided with a lower-layer flexible electrode. According to the invention, the performance of the sensor is improved by taking the composite material conductive aerogel with the gradient zero Poisson ratio structure as a dielectric layer and adding the substrate film of the nano-cellulose.

Description

Gradient zero Poisson ratio structure capacitive flexible touch sensor and preparation method thereof

Technical Field

The invention relates to the field of flexible touch sensors, in particular to a gradient zero Poisson ratio structure capacitive flexible touch sensor and a preparation method thereof.

Background

The flexible touch sensor refers to a touch sensor with physical characteristics similar to human skin, and can be covered on any carrier surface to measure stress information, so that the characteristic features of a target object can be sensed. The flexible sensitive skin of the robot becomes a research hotspot in the technical field of intelligent robot tactile sensors. For example, a medical robot equipped with a high-sensitivity flexible tactile sensor can detect the temperature, humidity and the like of human organs, and provide real-time and accurate tactile information for surgeons.

However, in response to the increasingly higher performance requirements, the conventional flexible tactile sensors, such as CN108827503A and CN110108393A, are too simple in structure, and none of the currently mainstream flexible tactile sensors can simultaneously achieve multiple characteristics of high flexibility, high sensitivity and high detection limit; in the traditional 3D printing preparation method, the method is only applied to the manufacture of a dielectric layer mold or the manufacture of a dielectric layer, the molding precision or the production efficiency of the dielectric layer is improved, and the integrated manufacture of multiple materials of the sensor is not realized. This has created an urgent need for the development of future high performance flexible tactile sensors.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a capacitive flexible touch sensor with a gradient zero-Poisson ratio structure.

The invention also aims to provide a preparation method of the gradient zero Poisson ratio structure capacitive flexible touch sensor.

The purpose of the invention is realized by the following technical scheme:

the gradient zero Poisson ratio structure capacitive flexible touch sensor comprises an insulating surface bulge which is in contact with an external object, an insulating film and a substrate film; the bottom of the insulating surface bulge is provided with an insulating film, a dielectric layer with a gradient zero Poisson ratio structure is arranged between the insulating film and the substrate film, the dielectric layer is in direct contact with the insulating film and the substrate film respectively, the lower surface of the insulating film is provided with an upper-layer flexible electrode, and the upper surface of the substrate film is provided with a lower-layer flexible electrode.

The insulation surface protrusion is made of PDMS material.

The insulating film is made of PDMS material.

The dielectric layer with the gradient zero Poisson ratio structure is conductive aerogel made of PDMS, CNFs and Graphene composite materials.

The substrate film is a PDMS and CNFs composite film.

The other purpose of the invention is realized by the following technical scheme:

the preparation method of the gradient zero Poisson ratio structure capacitive flexible touch sensor comprises the following steps:

s1, optimizing the hardware of the 3D printing equipment;

s2, compiling a 3D printing control algorithm;

s3, regulating and controlling rheological properties of the printing material;

and S4, 3D printing of the whole body.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the invention develops a pressure detection process which takes PDMS/CNFs/Graphene conductive aerogel material with a gradient zero Poisson ratio structure as a touch sensor dielectric layer to deal with high-sensitivity micro-pressure to large loading, eliminates three-dimensional force deformation coupling, and reduces precision loss caused by signal decoupling;

2. according to the invention, the mechanical property of the composite material is improved by adding the nano-cellulose, the conductive graphene can be prevented from agglomerating in the polymer in the dielectric layer, and the dispersion effect is good; adding nano-cellulose into the substrate material to improve the Young modulus of the substrate material so as to reduce the absorption of micro-pressure;

3. the invention adopts multilayer network structure design and 3D printing integrated molding technology to ensure that the sensor has multiple characteristics of high flexibility, high sensitivity and high detection limit, the preparation efficiency is high and the consistency of the single performance of the sensor is ensured.

Drawings

Fig. 1 is a schematic structural diagram of a gradient zero poisson's ratio structure capacitive flexible touch sensor according to the invention.

Fig. 2 is a diagram of a modified 3D printing hardware device.

Fig. 3 is a flowchart of the integral printing.

Wherein the reference numerals mean:

1-insulating surface raised; 2-an insulating film; 3-upper flexible electrode; 4-a dielectric layer; 5-lower flexible electrode; 6-substrate film.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

The capacitive flexible touch sensor with the gradient zero Poisson ratio structure comprises an insulating surface bump, an insulating film, a flexible electrode, a dielectric layer and a substrate film.

Furthermore, the insulation surface bulge is positioned on the uppermost layer of the capacitive flexible touch pressure sensor, is an arc bulge made of PDMS (polydimethylsiloxane) material and is a contact area between the capacitive flexible touch pressure sensor and an external object.

Furthermore, the insulating film is a flexible film made of PDMS material and is positioned on the lower layer of the insulating bulge.

Furthermore, the dielectric layer is conductive aerogel made of PDMS/CNFs/Graphene composite materials, has a gradient zero Poisson ratio structure, and is positioned at the lower layer of the insulating film.

Furthermore, the substrate film is a PDMS/CNFs composite film, can bear deformation caused by large external pressure, and is positioned at the bottom layer of the capacitive flexible touch pressure sensor.

Further, the flexible electrodes comprise an upper layer flexible electrode and a lower layer flexible electrode which are respectively arranged on the lower surface of the insulating film and the upper surface of the substrate film.

Further, a method for preparing the gradient zero Poisson ratio structure capacitive flexible touch sensor as claimed in claim 1, wherein the specific method is as follows:

and S1, optimizing the hardware of the 3D printing device.

And S2, writing a 3D printing control algorithm.

And S3, regulating and controlling rheological characteristics of the printing material.

And S4, 3D printing of the whole body.

Specifically, the capacitive flexible tactile sensor includes an insulating surface projection 1, an insulating film 2, a flexible electrode, a dielectric layer 4, and a substrate film 6. Wherein the uppermost layer is an insulation surface bulge 1 made of PDMS material and used for a contact area with an external object; an insulating film 2 is arranged below the insulating surface bulge 1 and is made of PDMS material; an upper layer flexible electrode 3 is arranged below the insulating film 2; a dielectric layer 4 is arranged below the upper-layer flexible electrode 3, PDMS/CNFs/Graphene composite aerogel with a gradient zero Poisson ratio structure is obtained, the crosslinking density is gradually increased by regulating and controlling the CNFs ratio from top to bottom, and an optimal gradient zero Poisson ratio structure is obtained by adopting theoretical calculation and finite element simulation based on the elastic performance of the composite material; a lower flexible electrode 5 is arranged below the dielectric layer 4; a substrate film 6 is arranged below the lower layer flexible electrode 5, and is a PDMS/CNFs composite film, and the appropriate Young modulus of the composite film is adjusted by adjusting and controlling the proportion of CNFs. The whole multi-layer network structure is combined to meet different external pressure detection, as shown in figure 1.

An existing commercial dual-nozzle 3D printing platform (Ultimaker S5) is improved, and a 4-nozzle printing device is designed, as shown in fig. 2.

On the basis, the diameter of the spray head is changed according to the rheological characteristics of different materials. And carrying out secondary development and optimization on the three-dimensional slicing software, and carrying out linear arrangement and filling on each layer of representative units on the basis of establishing a representative database. And importing CAD information and realizing integral integrated 3D printing. The flow is shown in fig. 3.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The capacitive flexible touch sensor with the gradient zero Poisson ratio structure is characterized by comprising an insulating surface bulge, an insulating film and a substrate film, wherein the insulating surface bulge is in contact with an external object; the bottom of the insulating surface bulge is provided with an insulating film, a dielectric layer with a gradient zero Poisson ratio structure is arranged between the insulating film and the substrate film, the dielectric layer is respectively in direct contact with the insulating film and the substrate film, the lower surface of the insulating film is provided with an upper-layer flexible electrode, and the upper surface of the substrate film is provided with a lower-layer flexible electrode;

the dielectric layer is conductive aerogel made of PDMS, CNFs and Graphene composite materials with gradient zero Poisson ratio structures, and the crosslinking density is gradually increased by regulating and controlling the proportion of the CNFs from top to bottom.

2. The gradient zero-poisson's ratio structure capacitive flexible tactile sensor of claim 1, wherein the insulating surface protrusion is made of PDMS material.

3. The gradient zero-Poisson's ratio structure capacitive flexible tactile sensor of claim 1, wherein the insulating film is made of PDMS material.

4. The gradient zero-Poisson's ratio structure capacitive flexible touch sensor of claim 1, wherein the substrate film is a PDMS, CNFs composite film.

5. The method for preparing the gradient zero-Poisson ratio structure capacitive flexible touch sensor is used for preparing the gradient zero-Poisson ratio structure capacitive flexible touch sensor as claimed in any one of claims 1 to 4, and comprises the following steps:

s1, optimizing the hardware of the 3D printing equipment;

s2, compiling a 3D printing control algorithm;

s3, regulating and controlling rheological properties of the printing material;

and S4, 3D printing of the whole body.