Simultaneous polydirectional transport of colloidal bipeds

TL;DR

This paper demonstrates the controlled, multi-directional transport of colloidal bipeds using magnetic fields, enabling complex operations like reactions, sorting, and pattern writing in colloidal systems.

Contribution

It introduces a method to design external magnetic field loops that direct colloidal bipeds along multiple paths for advanced colloidal manipulation.

Findings

Achieved parallel control of up to six classes of bipeds.

Enabled collision, polymerization, and separation of colloidal particles.

Demonstrated writing of words with colloidal bipeds.

Abstract

Detailed control over the motion of colloidal particles is relevant in many applications in colloidal science such as lab-on-a-chip devices. Here, we use an external magnetic field to assemble paramagnetic colloidal spheres into colloidal rods of several lengths. The rods reside above a square magnetic pattern and are transported via modulation of the direction of the external magnetic field. The rods behave like bipeds walking above the pattern. Depending on their length, the bipeds perform topologically distinct classes of protected walks above the pattern. We demonstrate that it is possible to design parallel polydirectional modulation loops of the external field that command up to six classes of bipeds to walk on distinct predesigned paths. We use such parallel polydirectional loops to induce the collision of reactant bipeds, their polymerization addition reaction to larger bipeds, the separation of product bipeds from the educts, the sorting of different product bipeds, and also the parallel writing of a word consisting of several different letters.