Light-fueled Non-reciprocal Self-oscillators for Fluidic Transportation and Coupling.

Light-fueled self-oscillators based on soft actuating materials have triggered novel designs for small-scale robotic constructs that self-sustain their motion at non-equilibrium states and possess bioinspired autonomy and adaptive functions. However, the motions of most self-oscillators are reciprocal, which hinders their use in sophisticated biomimetic functions such as fluidic transportation. Here, we report an optically powered soft material strip that can perform non-reciprocal, self-sustained oscillation under water. The actuator is made of planar-aligned liquid crystal elastomer responding to visible light. Two laser beams from orthogonal directions allow for piecewise control over the strip deformation, enabling two self-shadowing effects coupled in one single material to yield non-reciprocal strokes. The non-reciprocity, stroke pattern and handedness are connected to the fluidic pumping efficiency, which can be controlled by the excitation conditions. We demonstrate autonomous microfluidic pumping in clockwise and anticlockwise directions, translocation of a micro-object by liquid propulsion, and coupling between two oscillating strips through liquid medium interaction. The results can offer new concepts for non-equilibrium soft actuators that can perform bio-like functions under water. This article is protected by copyright. All rights reserved.