A Flexible Capacitive 3D Tactile Sensor With Cross-Shaped Capacitor Plate Pair and Composite Structure Dielectric

Abstract

This paper presents a novel flexible capacitive 3D tactile sensor using cross-bar polydimethylsiloxane (PDMS) walls and micropillar arrays as the composite structure dielectric layer. The tactile sensor unit consists of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> capacitor array where electrode pairs are arranged in a cross-bar pattern to ensure a fixed overlap area for these capacitors. A top bump is introduced for the sensor to ensure the force is applied uniformly on the sensor. When a force is applied on the sensor, it changes the capacitances of the four capacitors, distinguishing the forces from different directions. The sensitivities of the sensor in the x-, y- and z- directions are 95.08%/N, 98.30%/N and 237.48%/N, in the ranges of 0-0.15 N, 0-0.15 N and 0-0.1 N respectively, much better than most of reported ones. The high sensitivities of the proposed sensor unit are attributed to the composite structure dielectric layer and the optimized Young’s modulus of PDMS. The flexible capacitive tactile sensor shows great potential for applications in robot technology.