Enhanced shear separation for chiral magnetic colloidal aggregates

TL;DR

This paper explores how a simple four-sphere colloidal propeller, influenced by magnetic fields and shear flow, can be designed to achieve controlled drift and separation in microfluidic environments.

Contribution

It introduces a minimal colloidal propeller design that couples translation and rotation, enabling shear separation of chiral magnetic colloidal aggregates.

Findings

Migration velocity depends on cluster geometry.

Significant separation achievable under microfluidic conditions.

Magnetic and shear flow combination induces controlled drift.

Abstract

We study the designing principles of the simplest colloidal propeller, an architecture built from four identical spheres that can couple translation with rotation to produce controlled drift motion. By considering superparamagnetic beads, we show that the simultaneous action of a magnetic field and a shear flow leads to the migration of the cluster in the vorticity direction. We investigate the dependence of the migration velocity on the geometrical parameters of the cluster, and find that significant cluster separation can be achieved under the typical operation conditions of microfluidic devices.