Design,Preparation And Performance Study Of Nanofiber-Based Flexible Piezoresisitive Sensors

At present,the application scale of smart wearable devices has reached a whole new height,and the research on piezoresistive sensors has also made great progress.However,there are still challenges in the development of piezoresistive sensors that give consideration to sensitivity,detection limit,detection range,response and recovery time,and recycling.Electrospinning nanofibers with low Young’s modulus and high aspect ratio can achieve large compressive deformation by applying a small external pressure,making them an ideal material choice for the preparation of piezoresistive sensors.In this paper,based on electrospinning nanofibers,reduced graphene oxide（rGO）and poly（3,4-ethylenedioxythiophene）（PEDOT）were coated on the surface of nanofibers through biomimetic and other structural designs to achieve high electrical conductivity.At the same time,combined with the structural advantages of nanofibers,the preparation of high-performance piezoresistive sensors was realized.The details of the study are as follows:（1）rGO is coated with short polyacrylonitrile（PAN）nanofibers to form a flexible film,and then combined with the bi-directional pre-stretching method to build a random wrinkled structure,the rGO/nanofiber-based sensing active layer with a"layer-vein-wrinkle"tri-level structure is prepared,and finally encapsulated into a flexible piezoresistive sensor.Due to the contribution of nanofibers and wrinkled structures to the contact sites,the prepared sensor shows ultra-high cycling durability of 30,000 s,the detection range of 2.83 Pa-23.81 k Pa,and sensitivity of 318.14 k Pa^-1 at 0-2.83 k Pa,and can accurately recognize human activities such as touching,chewing,vocalizing,and fist clenching.（2）The 3D wrinkled nanofiber film with high specific surface area was created by pre-stretching.The three-dimensional（3D）wrinkled nanofiber network structure was then used as the structural carrier and the flexible PEDOT was selected as the conductive material to construct a sensing active layer by vapor phase polymerization for flexible piezoresistive sensors.This wrinkled nanofiber film（WNF）based flexible piezoresistive sensor has a linear sensitivity of 397.54 k Pa^-1 for small pressure（0-3 k Pa）detection,and an ultra-wide detection range of 1 Pa-25 k Pa,with response and recovery times reduced to 80 ms and 30 ms,respectively.In addition,the sensor can accurately identify subtle or significant signals such as wrist pulse and joint flexion.