CN-121994380-A - Low-drift flexible touch sensor and preparation method thereof

Abstract

The invention relates to the technical field of flexible touch sensors, in particular to a low-drift flexible touch sensor and a preparation method thereof, wherein the low-drift flexible touch sensor sequentially comprises a flexible substrate, a conductive layer and interdigital electrodes; the flexible substrate is a polydimethylsiloxane flexible substrate doped with silica nanoparticles. According to the invention, through optimizing the structure of each part of the sensor, the sensor drift caused by each part is fundamentally reduced, so that the signal drift of the sensor is reduced, the prepared low-drift flexible touch sensor can realize low-drift response under constant external force, the accuracy of the flexible touch sensor is greatly improved, and the stability of an output signal of constant external force detection is improved.

Inventors

• YANG XIAONIU
• WANG WEIWEI
• ZHANG TONG

Assignees

• 中国科学院长春应用化学研究所

Dates

Publication Date

20260508

Application Date

20260212

Claims (10)

1. 1. A low-drift flexible touch sensor sequentially comprises a flexible substrate, a conductive layer and interdigital electrodes; The flexible substrate is a polydimethylsiloxane flexible substrate doped with silica nanoparticles.
2. 2. The low drift flexible tactile sensor of claim 1, wherein said polydimethylsiloxane is prepared from a prepolymer by polymerization under the action of a curing agent; The mass ratio of the prepolymer to the curing agent is (2.5-20): 1.
3. 3. The low drift flexible tactile sensor of claim 2, wherein the mass ratio of the pre-polymer to the curing agent is 2.5:1.
4. 4. The low drift flexible tactile sensor of claim 1, wherein the silica has a doping ratio of 0.1% to 1%.
5. 5. The low drift flexible tactile sensor of claim 4, wherein a doping ratio of said silica is 1%.
6. 6. The low drift flexible tactile sensor of claim 1, wherein said conductive layer is a bulk stacked multiwall carbon nanotube.
7. 7. The low drift flexible tactile sensor of claim 1, wherein said interdigitated electrodes have a low roughness surface.
8. 8. The low drift flexible tactile sensor of claim 5, wherein said interdigitated electrode is an electrode sheet having a flexible sheet surface with a metallic material attached thereto; the flexible sheet is selected from polyethylene terephthalate, thermoplastic polyurethane elastomer, polyimide or polyethylene; the metal material is selected from gold, silver or copper; the surface of the electrode plate is provided with an interdigital pattern.
9. 9. The method for manufacturing the low-drift flexible tactile sensor according to any one of claims 1 to 8, comprising the following steps: Uniformly mixing a polydimethylsiloxane prepolymer, a curing agent and silicon dioxide nano particles in a first solvent to volatilize the first solvent, and curing the obtained mixed liquid in a mould with a microstructure to obtain a flexible substrate with the microstructure; dispersing the multi-wall carbon nano tube in a second solvent, spraying the multi-wall carbon nano tube solution on the surface of the flexible substrate with the microstructure, volatilizing the second solvent, and forming a conductive layer on the surface of the flexible substrate; Preparing an interdigital electrode, namely performing magnetron sputtering on a metal layer on the surface of a flexible sheet material to obtain a metal film with low surface roughness, and performing laser etching to obtain the interdigital electrode; And combining and packaging the interdigital electrodes and the flexible substrate attached with the conductive layer to obtain the low-drift flexible touch sensor.
10. 10. The method of claim 9, wherein the first solvent is n-hexane; the second solvent is N, N-dimethylformamide.

Description

Low-drift flexible touch sensor and preparation method thereof Technical Field The invention relates to the technical field of flexible touch sensors, in particular to a low-drift flexible touch sensor and a preparation method thereof. Background Along with the rapid development of flexible electronic equipment and the progress of robot technology, signal acquisition is more and more diversified and complicated, and higher requirements are put forward on the performance and application range of the sensor, so that the flexible touch sensor has wide application in the fields of man-machine interaction, touch perception, medical detection and the like due to the characteristics of light weight, thinness and softness, and becomes a current research hot spot. Flexible tactile sensors are classified into piezoresistive, piezoelectric, capacitive and triboelectric sensors according to their working mechanisms, and the piezoresistive flexible tactile sensor has the advantages of simple structure, convenient preparation, easy signal reading, high sensitivity in performance, wide detection range and the like, so that the flexible tactile sensor has been widely paid attention to by researchers. The sensing mechanism of the piezoresistive flexible touch sensor comprises two types of bulk conduction and surface conduction, wherein the bulk conduction is realized by distributing conductive substances in an elastomer, and the resistance of the elastomer changes after the elastomer is pressed, but the mechanism is greatly influenced by an elastic material body, and an output signal is unstable. The opposite surface conductivity type sensor is more stable in performance and its sensor structure mainly comprises a flexible substrate with a surface microstructure, a conductive layer and electrodes. The surface microstructure of the flexible substrate is various in morphology and comprises a regular microstructure, a random microstructure, a multilevel microstructure and the like, a conductive layer is attached to the microstructure, the material is generally carbon nano tubes, graphene, conductive polymers, metal materials and the like, the electrodes are generally in an interdigital shape, after the sensor is loaded, the flexible substrate is deformed, the contact area between the microstructure and the electrodes is increased, the conductive paths are increased, the resistance is reduced, the current is increased, and further the conversion from a force signal to an electric signal is realized. Through intensive research on microstructures, piezoresistive flexible touch sensors can realize high sensitivity and wide linear range, but the accuracy of most flexible touch sensors cannot meet the requirements, wherein one reason is that the sensors are difficult to stably respond, and when the sensors are subjected to constant force values, a signal drift phenomenon exists, which means that external load is constant, and the output current of the sensors is continuously increased along with time. The existence of drift has a lot of influence on the sensor, and it can increase measurement error, makes sensor calibration difficult, and the application is limited. Disclosure of Invention In view of the above, the technical problem to be solved by the present invention is to provide a low-drift flexible touch sensor and a manufacturing method thereof, wherein the manufactured flexible touch sensor has a low-drift characteristic under a constant external force. In order to achieve the above object, the present invention provides a low-drift flexible tactile sensor, which sequentially includes a flexible substrate, a conductive layer, and interdigital electrodes; The flexible substrate is a polydimethylsiloxane flexible substrate doped with silica nanoparticles. Fig. 1 is a schematic structural diagram of a low drift flexible tactile sensor provided by the invention. The surface of the flexible substrate is provided with microstructures, and the shape and the number of the microstructures are not particularly limited in the invention, and can be set according to shapes and numbers well known to those skilled in the art. In some embodiments of the invention, the microstructures are punctiform protrusions. The conductive layer is attached to the surface of the flexible substrate having the microstructure side, and the interdigital electrode is assembled with the conductive layer facing. The invention employs a polydimethylsiloxane flexible substrate doped with silica nanoparticles that has lower creep properties, and reduces the contribution of the flexible substrate to sensor creep by reducing creep of the flexible substrate material. In the invention, the polydimethylsiloxane is prepared by polymerization reaction of a prepolymer under the action of a curing agent. The mass ratio of the prepolymer to the curing agent is preferably (2.5-20): 1, more preferably 2.5:1. The prepolymer is a prepolymer for preparing polydimethylsiloxane. T