On Capacitive Pressure Sensor Based On Double-layer Microstructure Electrode

In recent years,flexible pressure sensors have been widely used in medical diagnosis,electronic skin and other fields due to their advantages such as flexibility and human compatibility.However,with in-depth research in these fields,higher requirements have been placed on the performance indexes of sensitivity,response time,hysteresis and repeatability of flexible pressure sensors,among which sensitivity is the most important.For the above problems,this thesis proposes a high-sensitivity capacitive flexible pressure sensor array based on double-layer microstructure electrodes.The main work of the thesis is as follows:Firstly,the preparation methods of capacitive flexible pressure sensor arrays based on double-layer microstructure electrodes were studied,including dielectric layer preparation,electrode layer preparation and sensor packaging,and four types of sensors with different microstructure sizes on the surface of the electrode layer were prepared.Specific research contents include:selecting polydimethylsiloxane(PDMS)with excellent elastic properties as the dielectric material,and preparing the dielectric layer by spin coating;selecting silver nanowires(AgNWs)with excellent electrical conductivity as the electrode material and PDMS with good flexibility and good insulation is used as the substrate material,and four different AgNWs/PDMS electrode layers were prepared using sandpaper with mesh numbers of 80,400,and 800 and smooth glass sheets as templates;the 7×7 electrode array adopts a "sandwich-type"structure combination,and a viscous PI film is used to complete the packaging of the sensor.Secondly,the performance test platform of the flexible pressure sensor was built,and the sensitivity test and optimization selection of the four sensors prepared above were completed.Through experimental comparison,it is proved that the method of manufacturing microstructures on the surface of the double electrode layer can improve the sensitivity of the sensor,which is 21 times that of the sensor without microstructure on the surface of the electrode layer;at the same time,the size of the microstructure on the surface of the double electrode layer is optimized and selected.It is determined that the capacitive flexible pressure sensor with double-layer microstructure electrode prepared with 80 mesh sandpaper as template has the highest sensitivity.Then the dynamic characteristics of the flexible pressure sensor with the highest sensitivity are tested.The test results show that the sensor has fast response time,good hysteresis characteristics and reliable repeatability.Finally,for a capacitive flexible pressure sensor array based on double-layer microstructure electrodes with the highest sensitivity,a signal acquisition system was built to verify its actual measurement effect.The system consists of the hardware and software of the lower computer and the software of the upper computer,which realizes the signal collection,processing,transmission and display of the sensor.The sensor is tested,and the test results prove that the sensor can perfectly detect the pressure of the object and the pressure distribution.The performance indexes of the capacitive flexible pressure sensor array based on the double-layer microstructure electrode designed in the thesis can meet the requirements of use.Compared with the traditional flexible pressure sensor,it has higher sensitivity and broader application prospects.