Programming Motion into Materials Using Electricity-Driven Liquid Crystal Elastomer Actuators
Lin Xu, Zhu Chen, Samuel C. Lamont, Xiang Zou, Yabing Yang, Si Chen, Jianning Ding, Franck J. Vernerey
Abstract
As thermally driven smart materials capable of large reversible deformations, liquid crystal elastomers (LCEs) have great potential for applications in bionic soft robots, artificial muscles, controllable actuators, and flexible sensors due to their ability to program controllable motion into materials. In this article, we introduce conductive LCE actuators using a liquid metal electrothermal layer and a polyethylene terephthalate substrate. Our LCE actuators can be stimulated at low currents from 2 to 4 A and produce a maximum work density of 9.4 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mstyle mathvariant="normal"> <mml:mi>k</mml:mi> <mml:mi>J</mml:mi> </mml:mstyle> <mml:mo class="MathClass-bin">∕</mml:mo> <mml:msup> <mml:mrow> <mml:mstyle mathvariant="normal"> <mml:mi>m</mml:mi> </mml:mstyle> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> . We illustrate the potential applications of this system by designing a palm-activated artificial muscle gripper, which can be used to grasp soft objects ranging from 5 to 55 mm in size, and even ring-shaped workpieces with precise external or internal support. Furthermore, inspired by the movement of fruit fly larvae, we designed a new soft robot capable of bioinspired crawling and turning by inducing anisotropic friction with an asymmetric design. Finally, we illustrate advanced motional control by designing an autonomously rotating wheel based on the asymmetric contraction of its spokes. To assist in the production of autonomously moving robots, we provide a thorough characterization of its motion dynamics.