Currents and flux-inversion in photokinetic active particles

TL;DR

This paper derives general formulas and an exact solution for directed transport of photokinetic particles under traveling light patterns, enabling efficient control and reconfiguration of active particles like colloids or bacteria.

Contribution

It provides asymptotic expressions for particle current under slow or fast light waves and an exact solution for the run-and-tumble model, advancing control strategies for photokinetic active particles.

Findings

Derived asymptotic formulas for particle current independent of wave shape.

Obtained an exact solution for the one-dimensional run-and-tumble model.

Results facilitate design of illumination patterns for particle manipulation.

Abstract

Many active particles, both of biological and synthetic origin, can have a light controllable propulsion speed, a property that in biology is commonly referred to as photokinesis. Here we investigate directed transport of photokinetic particles by traveling light patterns. We find general expressions for the current in the cases where the motility wave, induced by light, shifts very slow or very fast. These asymptotic formulas are independent on the shape of the wave and are valid for a wide class of active particle models. Moreover we derive an exact solution for the one-dimensional "run and tumble" model. Our results could be used to design time-varying illumination patterns for fast and efficient spatial reconfiguration of photokinetic colloids or bacteria.