Light-driven soft crawling robots capable of multidirectional locomotion and cargo transport

Abstract

This work presents a liquid crystal elastomer (LCE)-based light-driven crawling robot capable of rapid multidirectional locomotion and cargo transport. The proposed LCE device consists of two small front legs, two large rear legs, and a concave cargo platform connecting the legs. The device’s locomotion, inspired by the principle of snake-like rectilinear movement, is generated by activating the rear legs with periodic near-infrared (NIR) illumination. The device’s structure was formed monolithically using a lithography-based molding process followed by an LCE stretching process for shape programming. To enhance NIR absorption efficiency, the rear end of the device was coated with a photothermal film consisting of acrylic-based black paint and liquid metal nanoparticles. The device’s speed, which exceeds two body lengths per minute, is among the fastest recorded in published LCE-based, light-driven crawling devices. Furthermore, the device can change the locomotion direction by controlling the actuation sequences of NIR illumination on the rear legs. This research also demonstrated and characterized the device’s load-carrying capability, as it was able to move at about half its maximum speed while carrying a load heavier than itself.