Fabrication And Performance Of Multifunctional Flexible Pressure Sensor Based On Aramid Nanofibers

With the development of science and technology,we have entered a new era of the Internet of Things and artificial intelligence.Intelligent textiles,wearable electronic devices and soft robots prepared by flexible pressure sensors have begun to enter people’s lives,and are widely used in electronic skin,health care,sports equipment,aerospace,environmental monitoring and other fields.Flexible pressure sensors are portable,wearable,remote and real-time monitoring functions.In order to meet specific application scenarios,flexible pressure sensors should also integrate more beneficial functions,such as high temperature resistance,antibacterial,breathable,etc.Aramid fiber with high temperature resistance and good mechanical properties is an ideal choice for multifunctional flexible pressure sensor substrate.However,the application of aramid fiber in flexible pressure sensor is very limited at present,and the function of aramid based sensor has been reported to be relatively simple,and some material structures do not have flexible wearable properties.In this paper,the intermediate aramid nanofiber membrane with thin and wearable comfort was prepared by electrospinning technology.By combining different conductive materials and reasonable structure design,a flexible pressure sensor with high sensitivity,wide effective pressure detection range and multiple beneficial functions was obtained.The research work is described as follows:In the first part of the study,the structure of aramid carrier and its composite with conductive materials are studied,the meta-aramid（poly（m-phenylene isophthalamide）,PMIA）nanofiber membrane with flexibility and wearable comfort was prepared by simple electrospinning.The nanofiber membrane was modified by polydopamine（PDA）.Then Ag nanoparticles were loaded uniformly by in situ growth method.Finally,PMIA@PDA@Ag nanofiber membrane is assembled with copper foil to obtain a flexible piezoresistive sensor.The sensor has an excellent sensitivity of 46.59 k Pa^-1（0.66～2k Pa）,an ultra-low detection limit of 4.3 Pa,a wide detection pressure range of 0～10 k Pa,and good cycle durability.At the same time,the prepared PMIA@PDA@Ag nanofiber membrane has good mechanical properties,heat insulation properties,antibacterial properties and breathable properties.In the second part of the study,to further improve the sensitivity and effective pressure detection range of PMIA nanofiber membranes,the structure of the pressure-sensitive material was optimized in this paper.Nano-silicone filaments（SNF）were grown uniformly on the surface of PMIA nanofiber membrane,followed by uniform loading of polypyrrole（PPy）,after subsequent assembly,the PMIA@SNF@PPy nanofiber membrane flexible piezoresistive sensing was finally obtained.The surface of each nanofiber of PMIA nanofiber film is evenly grown with nano-silicone filament,which forms a dendritic structure and increases the conductive path,so that the prepared pressure sensor has better piezoresistive performance.The prepared PMIA@SNF@PPy nanofiber membrane flexible piezoresistive sensor demonstrated excellent sensitivity of 92.5 k Pa^-1（0.1～0.2 k Pa）,excellent detection range of 0～50 k Pa,rapid response,and excellent cycle durability.And PMIA@SNF@PPy-2 nanofiber membrane has good mechanical properties,thermal insulation,self-cleaning and breathable properties.