Highly Sensitive Tactile Sensor With Wide Dynamic Range Based on Multicontact Mechanism

Abstract

High-performance tactile sensors have become the important part of human–machine interaction, intelligent medical monitoring, industrial robots, and many other fields. However, high sensitivity and wide range are considered as contradictory aspects, so that the trade-off is always made between parameters. How to achieve the balance between them is a huge challenge. Herein, a novel tactile sensor is introduced based on the multicontact structure, which consists of two parts: the deformable top electrode with conductive spherical surface and the bottom electrode distributed with graphite nanosheets/polyimide (GNSs/PI) resistor array. Thereafter, the sensing mechanism of this new structure is systematically analyzed, which originates from changes in the contact resistance between overlapping electrode pairs and the expansion of the parallel equivalent circuit. Notably, tactile performances can be optimized by adjusting the curvature and conductivity of the top electrode, and the distribution pattern and density of the bottom electrode, leading to an outstanding sensitivity of 15.65 kPa−1 for low pressure (0–200 kPa) and 2.99 kPa−1 for high pressure (200–1400 kPa) with linearity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{\,2}$ </tex-math></inline-formula> higher than 0.95 in both intervals. Furthermore, the sensor shows relatively low detection limit (1 g), short response time (170 ms), and the excellent repeatability and durability advantageous to prolonged use. It is proven that the sensor design concept can be used as a preferred choice for accurate collection of tactile information and gives full support for the relevant applications of intelligent electronics.