Light-powered self-oscillation of a liquid crystal elastomer bow

Abstract

The self-oscillating system is capable of harvesting energy directly from a steady external environment to maintain its own continuous motion, without the need for an additional controller. It has potential application value in the fields such as micromachines, soft robotics and sensors. Currently, existing self-oscillating systems are relatively complex and difficult to fabricate and control, which limits their practical applications. In this paper, we present a novel light-powered self-oscillating liquid crystal elastomer (LCE) bow, composed of one LCE fiber, two cantilever beams and two masses, that can self-oscillate continuously and periodically under steady illumination. Considering the well-established dynamic LCE model and beam theory, we formulate the governing equation of the self-oscillating LCE bow and theoretically investigate its dynamics. Numerical calculations predict that the LCE bow always develops into one of two motion regimes: either static or self-oscillation. The self-oscillation is maintained by the LCE fiber which absorbs light energy to compensate for the damping dissipation. The control strategies and design principles for amplitude, frequency and equilibrium position of the self-oscillation are also investigated in details. The suggested LCE bow offers potential advantages in terms of simple structure, customizable size, flexible regulation and easy assembly, and these findings are expected to provide insights for the design and utilization of self-oscillating LCE bows in autonomous robots, energy harvesters, sensors and bionic design.