Preparation And Sensing Performance Of Flexible Resistive Pressure Sensor Based On Carbon Nanofibers

With the development of Internet of things,sensor technology plays a more important role in the modern information society.As a new type of information acquisition equipment,the flexible pressure sensor has the characteristics of bendability and malleability.It can work on special surface.Especially the device can be wearable on human skin for physiological signal detection,which is of great significance in flexible electronics,medical and health fields.In different types of pressure sensing mechanisms,the flexible resistive pressure sensor has attracted much attention due to its advantages of simple signal collection,good stability,and the ability of detecting dynamic and static pressure.Through the excellent design of sensitive materials and spatial structure,the performance of senor can be effectively improved.In this thesis,polyacrylonitrile（PAN）nanofiber film obtained by electrospinning is used as raw material to prepare carbon nanofiber（CNF）material by high temperature carbonization process.The CNF has low preparation cost,good pressure transfer performance,controllable conductivity and morphology,which has significant advantages in the field of flexible piezoresistive sensing.Based on CNF material,two preparation methods are proposed to obtain resistive pressure sensor with good flexibility and excellent sensing performance.The main work and the final results are as follows:1.The CNF self-supporting film obtained by carbonization was smashed into dispersed CNF by mechanical separation method.Then the dispersed CNF were uniformly combined with bacterial cellulose（BC）nanofibers to obtain CNF@BC composite pressure-sensitive film by solution ducting method.The composite film and flexible Ag electrode printed on polyimide（PI）substrate were assembled as a pressure sensor in sandwich structure.By analyzing the influence of carbonization temperature,recombination ratio,film thickness on the performance of the sensor,the optimum process parameters are determined.The finally obtained flexible resistive pressure sensor based on CNF@BC composite thin-film with a wide linear working range of 0～250 kPa and a sensitivity of 14.65[kPa]^-1 is realized,which can detect different pressure in a wide range.2.By doping CNT in the electrospinning precursor fluid,a flexible conductive CNF self-supporting film with 3wt%doping concentration of CNT was prepared,and the flexible resistive pressure sensor was obtained by assembling it with a screencast flexible electrode.By optimizing the process parameters such as carbonization temperature,spinning time,the finally obtained pressure sensor has high sensitivity up to 64.23[kPa]^-1 in the pressure range of 0～40 kPa.It can detect ultra-low pressure as low as 1 Pa and has excellent repeatability.When the sensor is used on the human body,it can accurately detect the specific waveform characteristics of the tiny pressure signal generated by pulse,breathing,pronunciation and other behaviors,which has a wide application prospect.