Dimeric colloidal inclusion in a chiral active bath: Effective interactions and chirality-induced torque

Area of Science:

• Soft Matter Physics
• Active Matter Systems
• Colloidal Science

Background:

• Colloidal inclusions in particle baths exhibit depletion interactions, typically attractive.
• Active particle baths introduce complex dynamics, altering inter-particle forces.
• Chirality in active particles can significantly modify emergent behaviors.

Purpose of the Study:

• To investigate the influence of channel confinement and bath chirality on forces and torques between colloidal inclusions.
• To understand how these factors modify the depletion interaction in active systems.
• To analyze the behavior of both fixed and freely rotating inclusion dimers.

Main Methods:

• Brownian dynamics simulations were employed to model the system.
• The study simulated colloidal inclusions within an active bath of smaller particles.
• Parameters varied included channel confinement, dimer orientation, and bath chirality strength.

Main Results:

• Channel confinement strongly affects effective interactions based on dimer orientation.
• Active particle chirality induces a net torque on the inclusion dimer.
• The transition from attraction to repulsion observed in nonchiral active baths is suppressed by chirality.

Conclusions:

• Confinement and chirality are critical factors governing interactions between colloidal inclusions in active baths.
• The findings provide insights into the design and behavior of active microstructures.
• This work highlights the tunable nature of forces and torques in confined active matter.