Iontronic pressure sensor with high sensitivity and linear response over a wide pressure range based on soft micropillared electrodes

基于微柱电极的高灵敏宽响应和高线性的离-电型压力传感器

Electronic skins and flexible pressure sensors are important devices for advanced healthcare and intelligent robotics.Sensitivity is a key parameter of flexible pressure sensors.Whereas introducing surface microstructures in a capacitive-type sensor can significantly improve its sensitivity,the signal becomes nonlinear and the pressure response range gets much narrower,significantly limiting the applications of flexible pressure sensors.Here,we designed a pressure sensor that utilizes a nanoscale iontronic interface of an ionic gel layer and a micropillared electrode,for highly linear capacitance-to-pressure response and high sensitivity over a wide pressure range.The micropillars undergo three stages of deformation upon loading:initial contact(0-6 k Pa)and structure buckling(6-12 k Pa)that exhibit a low and nonlinear response,as well as a post-buckling stage that has a high signal linearity with high sensitivity(33.16 k Pa-1)over a broad pressure range of 12-176 k Pa.The high linearity lies in the subtle balance between the structure compression and mechanical matching of the two materials at the gel-electrode interface.Our sensor has been applied in pulse detection,plantar pressure mapping,and grasp task of an artificial limb.This work provides a physical insight in achieving linear response through the design of appropriate microstructures and selection of materials with suitable modulus in flexible pressure sensors,which are potentially useful in intelligent robots and health monitoring.

电子皮肤是先进医疗设备和智能机器人智能感知的核心器件.在电子皮肤中引入微结构可以提高灵敏度,同时也导致信号的非线性较窄的压力响应范围,这极大地限制了电子皮肤的应用.本工作中,作者设计了一种电容式电子皮肤,这种传感器采用了一种微柱电极和一种离子凝胶,二者接触后形成的离子-电子界面的面积随着压力的上升而增大.实验发现这种传感器同时具有高灵敏度、高线性度以及较宽的压力响应范围.这种极高的线性度源于微结构受压后发生结构硬化以及凝胶-电极之间力学匹配带来的补偿效应.作者将这种传感器应用于脉搏检测、足底压力分析和假肢抓取的压力分布测试等,证明了其在智能机器人和健康监测中有巨大的应用潜力.该工作通过简单的结构设计和材料刚度的匹配实现了柔性压力传感器的线性响应,为传感器的线性响应设计提供了新的思路.