Preparation And Research Of Nano-silver Wire/polydimethylsiloxane Capacitive Flexible Sensor

In recent years,with the continuous development of technology intelligent terminals,flexible wearable electronic devices have broad market prospects,and flexible sensors have attracted wide attention as the core of wearable electronic devices.The flexible sensor has excellent biocompatibility,light and portable,stretchability and excellent responsiveness,which makes it have great development potential in the field of intelligence.Due to the limitations of process conditions,the preparation of flexible sensors with low cost,high sensing performance and detection of complex signals remains a huge challenge.Therefore,it is important to study flexible sensors with low cost and high sensing performance.In this paper,a flexible capacitive pressure sensor is fabricated using a simple method and process.Polymethylsiloxane(PDMS)is used as the flexible substrate and dielectric layer of the sensor,and nano silver wire(AgNWs)is used as the active material of the sensor.Assemble traditional capacitive flexible sensors to continuously optimize device structure in order to improve sensor performance.The main research contents of this thesis are as follows:(1)AgNWs with uniform morphology and high aspect ratio were prepared by polyol method.The AgNWs were characterized and analyzed by scanning electron microscopy and ultraviolet spectrophotometer.The average AgNWs prepared by us were obtained.The diameter is 0.103μm,the length is 41.7μm,and the aspect ratio is 404.8.(2)AgNWs/PDMS flexible electrode was prepared by drop coating method using AgNWs as active material and PDMS as flexible substrate.The electrical properties and electrical stability of the flexible electrode were investigated using a universal testing machine,scanning electron microscope and digital bridge.It was found that the flexible electrode prepared by dropping AgNWs in the semi-solid semi-liquid form of PDMS has excellent electrical conductivity and mechanical properties.(3)Sodium chloride was used as the porogen to prepare two kinds of sponge-like porous PDMS dielectric layers with different structures.Based on this,five different dielectric layers were constructed.The sensitivity,hysteresis characteristics,response characteristics and stability properties of the capacitive flexible sensor were studied by using the AgNWs/PDMS flexible electrode prepared above.It was found through testing that the dielectric layer combined with the air-air gap of the sponge porous PDMS can greatly improve the performance of the sensor.The prepared sensor has a sensitivity of 0.94 kPa-1 at low pressure(less than 500 Pa),and has good response characteristics and stability.(4)The sensor’s initial relative capacitance change value in the 5000 second continuous cycle test differs from the relative capacitance change value at the end by only 1%.In addition,the sensor has been tested in practical applications,including pulse monitoring,micro-weight measurement,click mouse response and finger bending test.The sensor shows excellent performance in the application.