Interaction of Active Janus Particles with Passive Tracers

TL;DR

This study explores how active Janus particles interact with passive tracers, revealing collision-dependent effects on particle motion and organization, including novel behaviors at higher concentrations.

Contribution

It provides new insights into collision dynamics and organizational patterns of active-passive particle systems in two dimensions.

Findings

Short collisions do not affect active particle motion.

Moderate/long collisions significantly alter motion and induce rotation.

Passive tracers form organized structures depending on collision nature.

Abstract

In this study, we investigated the motion of active SiO2-Pt Janus particles in the 2D bath of smaller silica tracers dispersed in varying areal densities. The effect on the organization of the tracer particles around the active JPs was also explored. Our experiments indicate that the interaction between the tracers and the active JPs mainly depend on the nature of collision marked by the duration of contact. For all the concentration regimes, we have shown that the short time collisions do not have significant impact on the motion of active JPs, however, during moderate/long-time collisions tracer(s) can lead to a significant change in active JPs motion and even cause them to rotate. In the concentrated regime, our experiments reveal the emergence of a novel organizational behavior of the passive tracers on the trailing Pt and the leading SiO2 with a strong dependence on the nature of collision.