Controlling Excitations of Work-Generating Cycles in Living Chiral Crystals

Living active materials can exhibit complex dynamic behaviors. In a living chiral crystal (LCC) formed by spinning starfish embryos, we observe spontaneous transitions between two steady states: a fluctuating state and an oscillatory state. In the oscillatory state, cycles in velocity and strain phase space allow us to extract work from the system's nonequilibrium dynamics. By applying uniaxial oscillatory compression, we can synchronize the LCC with the actuator when the oscillation period matches the embryos' rotation timescale. Additionally, a simple uniaxial step compression can shift the system from a fluctuating to an oscillatory state. These results highlight strategies for controlling and harnessing the nonequilibrium properties of active matter.