A light-fueled self-oscillator that senses force.

Abstract

Light-responsive materials with intrinsic negative feedback enable self-oscillation in non-equilibrium states. Conventional systems rely on self-shadowing in bending modes but fail when shadowing is constrained. Here, we demonstrate that external mechanical forces can bypass this limitation, enabling sustained oscillations without complete shadowing. Using a vertically suspended light-responsive liquid crystal network (LCN) strip under constant irradiation, a transition from static deformation to continuous oscillation arises when a critical load is applied. This system reveals two key phenomena: (1) oscillation amplitude scales with light intensity, reaching an angular displacement of 300°-significantly surpassing bending-mode oscillators; and (2) oscillation frequency decreases with increasing load, reflecting intrinsic mechanical sensitivity. This force-assisted self-oscillation principle generalizes across diverse deformation modes, including bending, twisting, contraction, and off-axis LCN strips. By mimicking biological mechanosensation based on dissipative mechanism, our findings provide a simplified design for non-equilibrium matter capable of dynamic adaptation to mechanical loads.