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

Peng Lu; Liu Wang; Pang Zhu; Jun Huang; Yueji Wang; Ningning Bai; Yan Wang; Gang Li; Junlong Yang; Kewei Xie; Jianming Zhang; Bo Yu; Yuan Dai; Chuan Fei Guo

doi:10.1016/j.scib.2021.02.019

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

Sci Bull (Beijing). 2021 Jun 15;66(11):1091-1100. doi: 10.1016/j.scib.2021.02.019. Epub 2021 Feb 9.

Authors

Peng Lu¹, Liu Wang¹, Pang Zhu¹, Jun Huang¹, Yueji Wang¹, Ningning Bai¹, Yan Wang¹, Gang Li¹, Junlong Yang¹, Kewei Xie¹, Jianming Zhang², Bo Yu³, Yuan Dai⁴, Chuan Fei Guo⁵

Affiliations

¹ Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
² Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China.
³ Ningbo Fengcheng Advanced Energy Materials Research Institute, Ningbo 315500, China.
⁴ Tencent Robotics X, Shenzhen 518000, China.
⁵ Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China; Centers for Mechanical Engineering Research and Education at MIT and SUSTech & Shenzhen Engineering Research Center for Novel Electronic Information Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China. Electronic address: guocf@sustech.edu.cn.

PMID: 36654343
DOI: 10.1016/j.scib.2021.02.019

Abstract

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 kPa) and structure buckling (6-12 kPa) 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 kPa^-1) over a broad pressure range of 12-176 kPa. 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.

Keywords: Flexible pressure sensor; Iontronic interface; Linearity; Mechanical matching.