Abstract:

Self-oscillatory systems sustain continuous motion by harvesting energy from a steady environment through internal feedback. In contrast to conventional oscillators that depend on inertia and demand materials with rapid responsiveness to external stimuli, in this study, we experimentally design a bistable liquid crystal elastomer (LCE) self-excited oscillator operating under steady illumination. The oscillator consists of an LCE fiber, a spring, a rigid rod, a rope, and a hysteretic occluder. A quasi-static analysis under constant light reveals two distinct motion regimes: a steady regime and a self-oscillatory regime. Periodic motion arises from the contraction and relaxation of the LCE fiber, leading to alternating leftward inclination of the rigid rod under illumination and rightward inclination in darkness. Owing to the bistable configuration, asynchronous motion is generated, introducing a hysteresis-related delay in the optical feedback. This hysteretic effect relaxes the requirement for rapid response and enables sustained self-excited oscillations under steady illumination. Furthermore, the dependence of the critical contraction strain and oscillation period on the system parameters is systematically examined. Compared with the existing self-oscillating systems, the proposed design achieves reliable self-excited oscillation with reduced experimental complexity and fewer mechanical components, enabling its potential use in sensing, energy harvesting, and soft robotics.

Key words: self-oscillation, liquid crystal elastomer (LCE), bistable, light-powered, quasi-static, hysteretic optical occlusion