Minimal model for active particles confined in a two-state micropattern

TL;DR

This paper introduces a minimal active Brownian particle model to replicate cell dynamics in a two-state micropattern, revealing how position-dependent rotational diffusion influences transition times and dwell durations.

Contribution

The model incorporates position-dependent rotational diffusion to accurately reproduce experimental transition statistics in confined active particles, highlighting the role of geometry and diffusion timescales.

Findings

Transition times depend on the rotational diffusion parameter $ au$.

An optimal $ au$ minimizes dwell time, tunable by pattern geometry.

Wall interactions dominate at large $ au$, increasing dwell time.

Abstract

We propose a minimal model, based on active Brownian particles, for the dynamics of cells confined in a two-state micropattern, composed of two rectangular boxes connected by a bridge, and investigate the transition statistics. A transition between boxes occurs when the active particle crosses the center of the bridge, and the time between subsequent transitions is the dwell time. By assuming that the rotational diffusion time $\tau$ is a function of the position, the main features of the transition statistics observed experimentally are recovered. $\tau$ controls the transition from a ballistic regime at short time scales to a diffusive regime at long time scales, with an effective diffusion coefficient proportional to $\tau$. For small values of $\tau$, the dwell time is determined by the characteristic diffusion timescale which decays with $\tau$. For large values of $\tau$, the interaction with the walls dominates and the particle stays mostly at the corners of the boxes increasing the dwell time. We find that there is an optimal $\tau$ for which the dwell time is minimal and its value can be tuned by changing the geometry of the pattern.