Magnetocapillary Swimmers

TL;DR

This paper demonstrates how a trio of soft ferromagnetic beads on a liquid surface can be made to swim by applying oscillating magnetic fields that induce non-reciprocal deformations, showcasing a novel magnetocapillary propulsion mechanism.

Contribution

It introduces a new experimental setup for magnetocapillary propulsion using soft ferromagnetic beads and oscillating magnetic fields, highlighting non-reciprocal deformation as a key to swimming.

Findings

Beads can be made to swim using magnetic field-induced deformations.

Oscillating magnetic fields create non-reciprocal shape changes.

The experimental setup demonstrates controlled magnetocapillary propulsion.

Abstract

We present an experiment where three mesoscopic soft ferromagnetic beads are placed onto a liquid surface and submitted to the influence of magnetic fields. A vertical magnetic field creates a repulsion which counterbalances the capillary attraction. We show that the competition with a second, oscillating field, deforms the structure in a non reciprocal way. As a consequence, the structure is able to swim. This experiment is fully described in a fluid dynamics video attached to this submission.