Biomimetic Inspired Liquid Crystal Elastomers with Dual-Mode Actuation Featuring Vapor Self-Oscillation and Photothermal Bending

Abstract

Soft actuators exhibit the capability of transducing environmental stimuli into mechanical motion, making them candidates for bionics and energy conversion. However, practical applications for emulation of complex behaviors in advanced organisms are hindered by lacking stimulus-discriminative multimodal motility in systems. Here, we fabricated three types of LCE films (LCE-1, LCE-2, and LCE-3) and experimentally confirmed that only LCE-1 exhibits multi-stimulus responsiveness, enabling dual-mode actuation under orthogonal stimuli. Under the fumigation of dichloromethane, continuous selfoscillation occurs, driven by asymmetric solvent adsorption across the two sides of the film. Gravity-assisted release of absorbed solvent ensures upward bending accompanied by downward motion. Additionally, the azobenzene-based liquid crystal actuator exhibits high photothermal conversion efficiency, reaching temperatures of up to 149.7 °C within 9 seconds, thereby enabling rapid and reversible photothermal actuation. Using LCE-1 structures of various geometries, a series of biomimetic systems were developed to reproduce the motions of four-petaled flowers, soft robots, crawling worms, and the complex locomotion of octopuses. The combination of vapor-and light-behaviors enable the autonomous realization of distinct movement modes in a single material system. The present work highlights the rational design of orthogonal stimuli and pave the way towards the applications of soft robots.