Research On Biologically Inspired Electronic Skin By Strain Visualization And Triboelectric Pressure Sensing

As one of the most sensitive and complex sensor networks of the human body,human skin can convert external environmental stimuli into physiological electrical signals for brain processing.As a wearable electronic device capable of sensing external stimuli,bionic electronic skin has attracted extensive attention in the fields of artificial intelligence,soft robotics and health monitoring in recent years.In order to make up for the shortcomings of the current multi-functional integration of electronic skin,such as stretchability,strain visualization and self-powered,and to provide ideas and practical basis for the realization of anisotropic tensile strain sensing of electronic skin in two-dimensional plane.In this paper,through the pressure sensing characteristics of coupled triboelectric nanogenerator(TENG)and the discoloration mechanism of cephalopod,we prepared a stretchable multi-functional three-dimensional electronic skin(SMTE)which can realize in-plane strain visualization and vertical pressure sensing.This paper provides a more extensive application of electronic skin in the fields of artificial intelligence and health monitoring,and has obvious innovation.The main contents of this paper are as follows:First,Silicone rubber(Ecoflex)with good flexibility,biocompatibility and light weight is used as the matrix material,the commercial phosphor with high stability as the efficient luminescent material,and the low-cost graphite powder as the shading material to prepare SMTE.Due to Poisson’s ratio,the size of the strip "shutter" microcrack becomes larger when it is stretched transversely,but closes when it is stretched longitudinally,and controls the light transmission area of the bottom fluorescence.Therefore,the local strain distribution can be directly reflected by vision.By studying the optimal crack size and spacing,SMTE can realize tensile sensing by color change in the transverse strain range of 0-120%,and tensile sensing by light intensity change in the longitudinal strain range of 0-100%,and the fluorescence intensity can be reduced by more than 60%.The prepared SMTE can realize sensitive and stable in-plane tensile strain sensing.Second,by spraying the Ag NWs conductive network with high aspect ratio on the fluorescent film as the stretchable electrode and the fluorescent film as the friction layer,the TENG with single electrode mode is used for vertical pressure tactile sensing.The open circuit voltage can reach 28.3 V and the charge transfer can reach 6 n C.For vertical pressure sensing,high sensitivity up to 40.22 V/k Pa or 0.61 n C/k Pa can be achieved.More than 5000 cycle tests show that the prepared triboelectric devices can work stably for a long period.Third,the appropriate shape of SMTE is integrated on the fingers of the manipulator model,and the relationship between different finger bending angles and the corresponding optical signals is studied.The gestures of "badminton" and "seal" grasped by the manipulator can be effectively identified by observing the fluorescence distribution.While maintaining visual strain perception,SMTE can get the corresponding voltage signal through different degrees of touch.The voltage of thumb is about11.8 V and that of little finger is about 2.51 V.In this way,SMTE can sense tiny touch,while self-powered triboelectric sensor and visual sensor coupling can provide more tactile information.In a word,SMTE endows the sensor with anisotropic multidimensional sensing characteristics through the combination of vision and triboelectric sensing,and has a potential application prospect in human-computer interaction,soft robot and artificial intelligence.