Curvature induces and enhances transport of spinning colloids through narrow channels

TL;DR

This study investigates how curvature influences the transport of spinning colloidal particles in narrow channels, revealing that curvature enhances propulsion and collective transport through hydrodynamic effects, combining experiments and simulations.

Contribution

It introduces the first combined experimental and simulation analysis of curvature effects on spinning colloids in narrow channels, highlighting the role of hydrodynamic coupling.

Findings

Curvature enhances particle propulsion via hydrodynamic coupling.

Spinning particles exhibit a positive rotation-translation coupling.

Curved channels facilitate collective transport of colloids.

Abstract

The effect of curvature and how it induces and enhances the transport of colloidal particles driven through narrow channels represent an unexplored research avenue. Here we combine experiments and simulations to investigate the dynamics of magnetically driven colloidal particles confined through a narrow, circular channel. We use an external precessing magnetic field to induce a net torque and spin the particles at a defined angular velocity. Due to the spinning, the particle propulsion emerges from the different hydrodynamic coupling with the inner and outer walls and strongly depends on the curvature. The experimental findings are combined with finite element numerical simulations that predict a positive rotation translation coupling in the mobility matrix. Further, we explore the collective transport of many particles across the curved geometry, making an experimental realization of a driven single file system. With our finding, we elucidate the effect of curvature on the transport of microscopic particles which could be important to understand the complex, yet rich, dynamics of particle systems driven through curved microfluidic channels.