Colloids in Two-Dimensional Active Nematics: Conformal Cogs and Controllable Spontaneous Rotation

TL;DR

This paper demonstrates how to design colloids in active nematics with controllable propulsion and rotation, using conformal mappings to predict behavior and establish design principles for desired dynamics.

Contribution

It introduces a method to design colloids with specific active rotational behaviors in nematic environments, utilizing conformal mapping techniques.

Findings

Chiral cogs exhibit orientation-dependent handedness.

Colloids can achieve persistent active rotation.

Design principles enable control over rotational dynamics.

Abstract

A major challenge in the study of active systems is to harness their non-equilibrium dynamics into useful work. We address this by showing how to design colloids with controllable spontaneous propulsion or rotation when immersed in active nematics. This is illustrated for discs with tilted anchoring and chiral cogs, for which we determine the nematic director through conformal mappings. Our analysis identifies two regimes of behaviour for chiral cogs: orientation-dependent handedness and persistent active rotation. Finally, we provide design principles for active nematic colloids to achieve desired rotational dynamics.