Synchronization and self-assembly of free capillary spinners

TL;DR

This paper explores how chiral floating spinners on a vibrated fluid surface self-assemble and synchronize through capillary wave interactions, demonstrating potential for controlled swarming behaviors.

Contribution

It introduces an experimental system of capillary spinners that self-assemble and synchronize via wave-mediated interactions, supported by a mathematical model.

Findings

Pairs of spinners form at quantized distances

Spinners can phase synchronize and rotate globally

The system demonstrates scalable swarming behaviors

Abstract

Chiral active particles are able to draw energy from the environment to self-propel in the form of rotation. We describe an experimental arrangement wherein chiral objects, spinners, floating on the surface of a vibrated fluid rotate due to emitted capillary waves. We observe that pairs of spinners can assemble at quantized distances via the mutually generated wavefield, phase synchronize and, in some circumstances, globally rotate about a point midway between them. A mathematical model based on wave-mediated interactions captures the salient features of the assembly and synchronization while a qualitative argument is able to rationalize global rotations based on interference and radiation stress associated with the wavefield. Extensions to larger collections are demonstrated, highlighting the potential for this tabletop system to be used as an experimental system capable of synchronizing and swarming.