Active colloids at fluid interfaces

TL;DR

This paper investigates how active Janus particles behave at fluid interfaces, revealing conditions that enhance their persistence length and aligning theoretical predictions with experimental observations.

Contribution

It provides a theoretical analysis of active Janus colloids at fluid interfaces, highlighting factors that increase their persistence length compared to bulk fluid conditions.

Findings

Persistence length can be significantly larger at interfaces.

Conditions for translation along the interface are identified.

Theoretical results align with recent experimental trends.

Abstract

If an active Janus particle is trapped at the interface between a liquid and a fluid, its self-propelled motion along the interface is affected by a net torque on the particle due to the viscosity contrast between the two adjacent fluid phases. For a simple model of an active, spherical Janus colloid we analyze the conditions under which translation occurs along the interface and we provide estimates of the corresponding persistence length. We show that under certain conditions the persistence length of such a particle is significantly larger than the corresponding one in the bulk liquid, which is in line with the trends observed in recent experimental studies.