Abstract
Electronic skin(e-skin)is a research focus in the fields of robotics design,artificial prosthetics,and wearable electronics.When used for long-term unattended monitoring,several key problems,such as energy supply,sensing performance,and structural design,have attracted increasing attention.This study reports a self-powered flexible e-skin sensor(FES)based on the thermal cyclization of polyacrylonitrile,which enhances the piezoelectric effect.It mainly consists of nanoscale polyacrylonitrile(PAN),Ecoflex,and flexible PCB electrodes.PAN is mixed as a piezoelectric functional material in the Ecoflex substrate,forming a flexible sensing module.To enhance charge accumulation,PAN is initially electrospun into nanofibers and subsequently modified through a thermal treatment process.This procedure results in the formation of a conjugated trapezoid structure within PAN and significantly increases its molecular dipole moment.Due to the contribution of numerous nanocapacitors,the pie-zoelectric properties of the sensing module are significantly improved.To ensure durability,flexible PCBs were designed as the top and bottom electrodes of the sensing module via industrial board lamination and forming processes,also serving as packaging.Additionally,a human-computer interaction(HMI)system for e-skin measurement was developed,enabling real-time signal processing between the e-skin and the computer.On the basis of the good combination of piezoelectric nanoparticles,an Ecoflex substrate,and flexible PCBs,FES can reach 0.67 V/kPa and 0.99 voltage sensitivity and voltage linearity,respec-tively,under self-powered conditions under external pressure,and the detection range can reach 40-650 kPa.On the basis of the good performance of FES devices,such as their self-powered ability,long-term serviceability,high sensitivity,wide monitoring range,and various optimized designs for later circuits,the e-skin designed in this paper has important applications in the fields of HMI,personality recognition,and medical research.
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