Electrically responsive knitted liquid crystal elastomer actuators for underwater applications

Abstract

Soft actuators present distinct advantages for underwater applications due to their inherent flexibility, which endows them with pressure resistance, quiet operation, and gentle manipulation. Among various materials, liquid crystal elastomers (LCEs) exhibit significant reversible deformation in response to external stimuli, making them promising candidates for the construction of soft actuators. However, the underwater implementation of LCE actuators remains challenging because rapid heat dissipation in water suppresses thermally driven actuation, while light‐triggered actuation suffers from limited light penetration and poor reliability in turbid or obstructed environments. Herein, we propose an electrically responsive knitted LCE actuator fabricated through a fiber‐to‐textile strategy for underwater soft robotics. In this integrated design, the actuator uses core–shell fibers, in which the liquid metal (LM) core serves as a soft conductive pathway for Joule heating, while the LCE shell provides reversible actuation and electrical insulation. This design enables efficient internal Joule heating, effectively compensating for the inhibitory effect of rapid underwater heat dissipation on LCE thermal actuation. Furthermore, the knitted topology converts the axial contraction of LCE fibers into programmable deformation. Based on this mechanism, the knitted LCE‐LM actuator achieves directional locomotion via topology‐induced asymmetric friction. It can be extended into object manipulation via a gripper design. This strategy presents a new design principle for LCE‐based underwater actuators and holds significant potential for underwater exploration, marine resource harvesting, and related fields.