Light-powered self-sustained jumper via splay-aligned liquid crystal elastomer

Self-oscillating systems efficiently convert constant external inputs into sustained periodic motion, making them ideal for a variety of applications, including soft robotics, energy harvesting, and reconfigurable logic circuits. Self-jumping is especially challenging due to its high energy requirements. Drawing inspiration from the attachment-jumping mechanisms of larval beetles, we propose a novel light-powered self-sustaining jumper based on a splay-aligned liquid crystal elastomer strip and a rigid adhesive substrate. Using a nonlinear beam model and Dugdale's cohesive law, we develop a dynamic model describing liquid crystal elastomer self-jumping under constant illumination. Quasi-static analysis reveals two modes: static and self-jumping. Because the photothermally-induced strain in the strip is constrained by the adhesive substrate, elastic energy gradually accumulates throughout the strip. Once this strain reaches a critical threshold, the stored energy is released abruptly, driving a rapid upward arching motion that lifts the strip off the substrate. During the jump, the photothermally-induced strain recovers, allowing the system to undergo a repeatable cycle comprising four distinct stages: gradual peeling, snap detachment, upward jump followed by downward fall, and snap re-attachment. The critical conditions for self-jumping are derived analytically. The key parameters governing maximum jump height and self-jumping period are also investigated systematically. The system offers controllable jump height, tunable period, and simple structure, with potential for soft robotics, sensors, and miniaturized devices.