Research On Flexible Pressure Sensor Based On Carbonized Cotton Fabric

As an important part of flexible electronic devices,flexible pressure sensors have shown great development prospects in the fields of health care,electronic skin and human-computer interaction.Carbonized fabric has attracted attention due to their excellent flexibility and electrical conductivity,as well as the merits of low cost,renewability and environmentally friendliness,and became the emerging sensing material for flexible pressure sensors.In this paper,conductive carbonized cotton fabric was prepared by simple carbonization process.Carbonized cotton fabric/thermoplastic polyurethane(TPU)composite was then obtained by dipping and drying method.Characterization including SEM,EDS,Raman,XPS electrical property and mechanical performance tests were performed.A flexible pressure sensor based on carbonized cotton fabric/thermoplastic polyurethane composite was then fabricated through simple assembly,which exhibited excellent mechanical performance and sensing performance.In order to investigate the influence of preparation process on the sensing performance of flexible pressure sensor,different carbonization temperatures(600°C,700°C,800°C,900°C,1000°C)and flexible substrate solution concentrations(4 wt%,6wt%,8wt%,10wt%)were set,then followed by characterization and test for carbonized cotton fabric and composite with different process parameters.And the sensing performance for flexible pressure was test.Finally,the carbonized cotton fabric/thermoplastic polyurethane based flexible pressure sensor with optimal process was selected for practical application test.Through the characterization of carbonized cotton fabric and its composite,the carbonization process transformed common cotton fabric into conductive carbon material with conductivity up to 59.31 S/m,and the fabric structure remained good.Composite added thermoplastic polyurethane have good flexibility and mechanical property.Flexible pressure sensor assembled from carbonized cotton fabric and thermoplastic polyurethane exhibited excellent sensing performance,including working range of 0?16 k Pa,sensitivity up to 74.799 k Pa^-1,hysteresis as low as 9.34%,low detection limit of?0.70 Pa and repeatability of 4000 cycles.By discussing the influence of process parameters on the sensing performance during the preparation process,it is concluded that the carbonization temperature and substrate material concentration have a great influence on the sensing performance of flexible pressure sensor.The conductivity and graphitized degree of carbonized cotton fabric varied with the carbonization temperature,and pressure sensor with different carbonization temperatures showed different sensitivity.The sensor carbonized at 800-900°C show superior sensitivity.The electrical and mechanical property of composite varied with the concentration of thermoplastic polyurethane,and sensors with different thermoplastic polyurethane concentrations exhibited different hysteresis and stability.The sensor prepared by 6 wt%thermoplastic polyurethane exhibited lower hysteresis.By placing rice on the sensor,and fixing the sensor on the wrist radial artery,finger and wrist to detect weak signal,pulse signal and human motion,the ability of carbonized cotton fabric composite based flexible pressure sensor to detect weak signal and strenuous motion was demonstrated,which showed great development prospects in flexible electronics.