Biomimetic Locomotion of Electrically Powered “Janus” Soft Robots Using a Liquid Crystal Polymer

TLDR

Oriented liquid crystal networks can reversibly change shape at macroscopic scale when mesogens undergo an order–disorder transition, a property exploited to create soft robots that move in response to external stimuli such as light. The study reports electrically driven soft robots capable of executing various biomimetic locomotion. The robots consist of a uniaxially oriented liquid crystal polymer strip laminated with Kapton and embedded resistive wires, forming a single‑piece Janus structure that deforms in opposite directions under uniform electrical stimulation, enabling complex shape morphing and multiple locomotion modes such as crawling, tube navigation, quadrupedal walking, and bipedal walking while carrying loads.

Abstract

Oriented liquid crystal networks (LCNs) can undergo reversible shape change at the macroscopic scale upon an order-disorder phase transition of the mesogens. This property is explored for developing soft robots that can move under external stimuli, such as light in most studies. Herein, electrically driven soft robots capable of executing various types of biomimetic locomotion are reported. The soft robots are composed of a uniaxially oriented LCN strip, a laminated Kapton layer, and thin resistive wires embedded in between. Taking advantage of the combined attributes of the actuator, namely, easy processing, reprogrammability, and reversible shape shift between two 3D shapes at electric power on and off state, the concept of a "Janus" soft robot is demonstrated, which is built from a single piece of the material and has two parts undergoing opposite deformations simultaneously under a uniform stimulation. In addition to complex shape morphing such as the movement of oarfish and sophisticated devices like self-locking grippers, electrically powered "Janus" soft robots can accomplish versatile locomotion modes, including crawling on flat surfaces through body arching up and straightening down, crawling inside tubes through body stretching and contraction, walking like four-leg animals, and human-like two-leg walking while pushing a load forward.