Pseudochemotaxis in inhomogeneous active Brownian systems

TL;DR

This paper investigates how inhomogeneous activity profiles influence the movement and target-finding efficiency of active Brownian particles, revealing a chemotaxis-like drift and validating findings with simulations and theoretical models.

Contribution

It introduces a theoretical framework for understanding pseudochemotaxis in active particles with inhomogeneous activity, supported by simulations and an approximate Fokker-Planck equation.

Findings

Increased target-finding probability with high-activity zones between start and target.

Decreased mean first passage time in inhomogeneous activity profiles.

Activity gradients induce a chemotaxis-like drift in active particles.

Abstract

We study dynamical properties of confined, self-propelled Brownian particles in an inhomogeneous activity profile. Using Brownian dynamics simulations, we calculate the probability to reach a fixed target and the mean first passage time to the target of an active particle. We show that both these quantities are strongly influenced by the inhomogeneous activity. When the activity is distributed such that high-activity zone is located between the target and the starting location, the target finding probability is increased and the passage time is decreased in comparison to a uniformly active system. Moreover, for a continuously distributed profile, the activity gradient results in a drift of active particle up the gradient bearing resemblance to chemotaxis. Integrating out the orientational degrees of freedom, we derive an approximate Fokker-Planck equation and show that the theoretical predictions are in very good agreement with the Brownian dynamics simulations.