Self-sustained soft robots based on liquid crystal elastomers

Abstract

Self-sustained soft robots capable of achieving continuous motions under consistent stimulus have become a new trend in robot development in recent years due to their self-sustained characteristics and no need for manually switching on/off stimuli. The sensitivity, reversibility, and multi-stimuli responsiveness of liquid crystal elastomers (LCEs) make them exceptionally suitable for the design and construction of self-sustained soft robots. This paper provides an overview of the recent progress in self-sustained soft robots based on LCEs. We begin with the mechanism of the self-sustained soft robots, which rely on negative feedback loops. Then they are classified into bi-directional reciprocation soft robots and uni-directional closed loop soft robots. Bi-directional reciprocation soft robots interconvert between metastable states and equilibrium states, including reciprocal self-oscillators, non-reciprocal self-oscillators, and fluctuating oscillators. Uni-directional closed loop soft robots with continuous cyclic structures convert to the next self-similar morphologies unidirectionally until completing a structural cycle, including self-rolling robots, snapping flipping robots, and continuous rotating robots. This review concludes with a perspective on the challenges and opportunities that lie ahead for the future development of self-sustained soft robots.