Model for active particles confined in a two-state micropattern.

The study uses a computational model based on active Brownian particles. The model simulates transitions between two rectangular boxes connected by a bridge. A transition occurs when a particle crosses the bridge's center. The dwell time is defined as the time between consecutive transitions. The model assumes that rotational diffusion time is position-dependent. This assumption allows the simulation to match experimental observations. The researchers analyze how dwell time varies with rotational diffusion time. They also examine how geometry influences the effective diffusion coefficient.

The model successfully reproduces the shape of the survival function observed in experiments. It shows that rotational diffusion time controls the transition from ballistic to diffusive motion. At short time scales, particles move ballistically. At long time scales, diffusion dominates with a coefficient proportional to rotational diffusion time. For small rotational diffusion times, dwell time is constant. When translational diffusion is much faster, dwell time remains unchanged. For intermediate values, dwell time decreases with increasing rotational diffusion time. Large rotational diffusion times increase dwell time due to wall interactions.

The model demonstrates that rotational diffusion time significantly affects transition dynamics. The dwell time reaches a minimum at an optimal rotational diffusion time. Geometry changes can tune this optimal value. The study confirms that wall interactions increase dwell time at high rotational diffusion times. The model provides a framework for understanding how confinement affects active particle behavior. It supports the idea that both motion types must be considered in confined systems. The findings suggest that micropattern geometry can be used to control particle dynamics. These results align with the authors' claim that the model captures essential features of cell motion in structured environments.