Soft Robotic Finger Based on Double-Layer Liquid-Crystal Elastomer With Built-In Grid Structure Pressure Sensor

Abstract

The soft hand allows for flexible and safe object grasping by utilizing tactile sensitivity to gather information about the object, thereby minimizing potential damage to its surface. However, the integration design of the drive and sensor faces significant challenges due to variations in driving mode and substrate material properties. This research presents a soft hand design based on a liquid crystal elastomer (LCE) integrated with a capacitive pressure sensor in the finger. The finger-bending part of the soft hand is composed of an LCE driven by a low-pressure (6 V) electric heating film, and the finger sensor component consists of a flexible capacitive pressure sensor with a grid-like structure of electrodes and a PU sponge medium. Among them, the electric heating film is prepared from polyimide (PI) with imprinted gate electrodes, and the flexible capacitive sensor is prepared from an electrode composed of LCEs with an imprinted grid structure and filled with multiwalled carbon nanotubes (MWCNTs), with a porous PU sponge as the medium. The flexible capacitive pressure sensor has a sensitivity of up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.06875\,\,\text {kPa}^{-{1}}$ </tex-math></inline-formula> in the low-pressure range. This method of integrating the sensor on an LCE film achieves pressure sensing and demonstrates the potential of LCE films for gripping objects and sensing recognition applications.