Light-induced non-uniform surface polarization evolution as an active matter motion mechanism.

Abstract

A new mechanism for micro-swimmer motion in an aquatic environment, which implies light-induced polarization perturbations as a cause for motion, is proposed. The mechanism assumes that natural light leads to an enhancement of the non-uniform polarization distribution at the micro-swimmer's surface and also to an enhancement of its surface deformations. The interaction of such non-uniform polarization with free charges in the environment and the mechanical interaction of surface deformations with media flows lead to directed micro-swimmer motion. The thermodynamic justification for this mechanism is based on the free energy functional minimization in terms of polarization. The obtained solutions of the non-uniform polarization distribution correspond to its translation motion along and the rotation around the micro-swimmer surface. The estimation of the velocity of micro-swimmer motion, which is based on the hydrodynamics of the active matter, corresponds to the experimentally observed values.