Effects of optically absorbent coatings on parallel optical control of levitating milli-robots

Abstract

Passively levitating pyrolytic graphite (PyG) milli-robots can be controlled optically due to the thermal dependence of PyG’s magnetic susceptibility and optically induced, localized temperature changes. A combination of projector technology and optically absorbent coatings is proposed to address the challenge of simultaneous parallel control of levitating PyG milli-robots. Experimental results demonstrate successful parallel control using commercially available projector technology. Experimental actuation responses show marginal ability of absorbent coatings to increase PyG robot maximum actuation speed as well as reduce minimum controllable robot size under fixed optical power density constraints. While enhanced optical absorption opens opportunities for system miniaturization and extension to device-level magneto-optic actuators, doing so with minimal impact to levitating properties in a highly thermally conductive material remains a challenge.