Fabrication And Properties Of Carbon Materials- Based Flexible Pressure Sensors

In recent years,with the rapid development of wearable and skin-mountable electronic devices,electronic sensors,as one of their indispensable components,are in the hot research direction.In the future,the development of various high-performance sensors will be in full gear.Among them,flexible pressure sensors have attracted extensive attention because of their potential applications in human motion detection,personal health monitoring,human-computer interaction and other aspects.In order to meet the above conditions,it is necessary to adopt rational design to obtain high-performance,low-cost and wearable devices.At present,many high-performance flexible pressure sensors have been developed:some of them have high sensitivity,some have a wide detection range,some have ultra-fast response time.However,it is difficult to integrate those high-performance parameters into one device simultaneously.In addition,in the common device preparation processes,some of which have cumbersome preparation and complicated procedure,such as ultrafiltration,chemical vapor deposition（CVD）growth and spray-coating,some use noble metals as conductive materials which are costly,and some inevitably produce by-products,such as air pollutant.Therefore,to solve the above dilemma,this paper proposes two kinds of flexible pressure sensors based on carbon materials,and carries out systematic research from the aspects of manufacturing process,performance characterization and relevant practical applications of devices,etc.The main research contents are as follow:（1）Flexible pressure sensors based on stretchable materials.First,cotton-based bottom electrodes was made by screen-printing with conductive silver paste.Then,Polydimethylsiloxane coated with nano carbon black was used as the top bridge part.At last,integrate the bottom and top parts and complete the encapsulation.Owing to the unique loose porous structure and the larger surface roughness of the textile and the tensile properties of PDMS,the pressure sensor exhibits excellent performance,such as high sensitivity(31.63 kPa^-1,in the 0-5 kPa range),rapid response（response time and relaxation time of 15 and 20 ms,respectively）.（2）All-fabric flexible pressure sensors based on carbon materials.Firstly,the cotton fabric bottom electrode was prepared.Secondly,carbon black（CB）were fumed evenly on the surface layer of the non-woven fabric by the fumigation method,and then the solution of poly 3,4-ethylene dioxothiophene/polystyrene sulfonate（PEDOT:PSS）was drop coated on the CB for fixation.At last,bond the bottom and top parts and complete the encapsulation.And an all-fabric flexible pressure sensor with high sensitivity(81.61kPa^-1,in the 0-10 kPa range)and wide detection range（0-100 kPa）as well as ultra-fast response time（6 ms）could be fabricated.Based on the excellent performance of the device,it can not only detect the subtle sound vibration and tiny body movements,but also detect the human pulse waveform signal,realizing the detection of human physiological signals and showing its potential for health monitoring.