Pulling and Pushing a Cargo With a Catalytically Active Carrier

TL;DR

This paper models a micro-scale cargo carrier system using catalytically active particles, revealing how orientation affects movement and identifying optimal configurations for effective cargo transport.

Contribution

It introduces a simplified model of a catalytically active carrier connected to cargo, highlighting the importance of orientation and configuration in propulsion efficiency.

Findings

Velocity depends on the relative orientation of carrier and cargo.

Optimal linkage configuration maximizes movement.

A fully catalyzed sphere can act as a carrier when attached to cargo.

Abstract

Catalytically active particles suspended in a liquid can move due to self-phoresis by generating solute gradients via chemical reactions of the solvent occurring at parts of their surface. Such particles can be used as carriers at the micro-scale. As a simple model for a carrier-cargo system we consider a catalytically active particle connected by a thin rigid rod to a catalytically inert cargo particle. We show that the velocity of the composite strongly depends on the relative orientation of the carrier-cargo link. Accordingly, there is an optimal configuration for the linkage. The subtlety of such carriers is underscored by the observation that a spherical particle completely covered by catalyst, which is motionless when isolated, acts as a carrier once attached to a cargo.