Smart Soft Actuators and Grippers Enabled by Self-Powered Tribo-Skins

Soft end effectors or grippers capable of grasping objects dexterously and efficiently have attracted increasing attention in a broad range of applications. This article describes a smart soft finger-like actuator with fast response, accurate control, self-powered pressure, and bending sensing capability by combing the cable-driven actuation with soft triboelectric nanogenerators (TENGs). The soft actuator, driven by a miniature DC motor, is designed to have multiple segments of elastomer body split with triangular cuts to facilitate the bending actuation and conformal contact with target objects. Two types of TENGs are integrated with the soft actuator: a single-electrode-mode TENG to measure the contact pressure and an inner contact-separation-mode TENG to detect the bending. With micropyramid structures, the tribo-skin patches possess high sensitivity and good compatibility with the actuator and can actively detect proximity, contact, and pressure via self-generated electricity. Based on the modular design approach, a gripper with three fingers is fabricated and tested for its grasping, sensing, and self-powering performance. This gripper is capable of picking up different kinds of objects, providing sensory feedback, and generating electricity, which shows great potential for use in robot-human and robot-environment interaction applications.