C. elegans-inspired undulatory motion in a light-driven liquid crystal elastomer fiber

Undulatory movement is widely observed in the animal kingdom, from snakes and earthworms to microorganisms. Mimicking such deformation is important in soft robotics in terms of locomotion control and navigation efficiency. However, realizing such motion at miniature scales in fluid environments remains difficult for soft actuators. Here, we present light-controlled undulatory motion inspired by C. elegans, realized in a millimeter-scale liquid crystal elastomer (LCE) fiber actuator under water. We use the sequential excitation of four laser beams to generate bimorphic actuation between two segments of the LCE, with a 45-degree phase delay between two consequent deformation phases. The actuator demonstrates stable figure-eight-like trajectories and directional steering through laser power modulation. Furthermore, the actuation performance scales with fiber length, providing amplitude tuning and demonstrating programmable control of locomotion.