Preparation And Properties Of Flexible Electronic Sensors Based On EGaIn

Flexible electronic sensors refer to sensors made of flexible materials,with good suppleness,ductility,flexibility and other characteristics,showing broad application prospects in the field of wearable electronics.However,the high cost of manufacturing process,poor transparency,poor conformality and other problems limit the wide range application of flexible electronic sensors.Therefore,new flexible electronic sensors with smaller size,lower cost,lighter weight,and easier portability have caused widespread concern.In view of the above problems,this paper adopts the screen printing process to fabricate a transparent and thin flexible electronic sensor by modifying eutectic gallium-indium（EGa In）liquid metal alloy ink on the flexible substrate.SEM and EDS techniques were used to characterize the structure,and the electrical properties of the sensor such as sensitivity,response time,fatigue cycle and so on were investigated.The specific work is as follows:First,with styrene-butadiene-styrene（SBS）film as substrate,a flexible strain sensor based on EGa In ink was fabricated by screen printing process.Through experimental exploration,the ink of 1:4 ratio of polyvinylpyrrolidone（PVP）:EGa In has excellent electrical conductivity;in the strain range of 0～120%,the sensor based on 1:4 ratio ink,90°bending angle and 1.2 mm circuit width has a large sensitivity,reaching 1.5 mm^-1;under 40%strain tension,the sensor has more than 500 fatigue cycles.The sensor provides excellent real-time monitoring of finger bending as well as human motion,showing some potential applications.Second,three flexible capacitive sensors based on EGa In ink were prepared by screen printing process with silica gel film as the substrates and three thin film materials of silica gel film,polyethylene film（PE）and polyimide film（PI）as the dielectric layers.Through experimental exploration,the capacitive sensor based on PI film dielectric layer with a 0.0125 mm thickness can detect a very small pressure of 0.02 N and can maintain a stable electrical signal response under a high pressure of 25 N;in the pressure range of0.8 k Pa to 3.2 k Pa,it has a high sensitivity of 0.253 k Pa^-1;the response time under 100 g pressure is 400 ms,the recovery time is 600 ms,and it has more than 400 fatigue cycle performance.The sensor can be used as a sensing unit in array sensing.Third,On the basis of the sensor prepared above,combined with the shape memory composite electric driving material,the driving material Vitrimer is sensed in real time.Through experimental exploration,when the Vitrimer material is deformed from temporary shape to permanent shape,the capacitance can return to the original state value.When the Vitrimer material is crushed and recycled for secondary processing,the initial and final state resistance does not change significantly,while the initial and final state capacitance has a slight change,and the difference between the front and back capacitances is 3 p F.Based on the feasibility of direct transfer of EGa In ink onto the Vitrimer substrate,a sandwich structure with integrated actuating and sensing was successfully prepared,which can sense a minimum strain of 4%and has a high sensitivity of 1.2 mm^-1 in the 0～4%%strain range.This research provides data support for the potential application of related technologies in the aerospace field.