Threaded rings that swim in excitable media

TL;DR

This paper introduces a novel topological configuration called a threaded ring in excitable media, demonstrating through simulations and experiments that it exhibits unique swimming behavior in the plane of the ring.

Contribution

The study presents the first experimental realization and simulation of a threaded ring in excitable media, revealing its exotic swimming dynamics.

Findings

Threaded rings can be created in photosensitive Belousov-Zhabotinsky media.

The threaded ring exhibits a unique swimming motion in the plane of the ring.

Experimental and simulation results confirm the existence and behavior of the thring.

Abstract

Cardiac tissue and the Belousov-Zhabotinsky reaction provide two notable examples of excitable media that support scroll waves, in which a filament core is the source of spiral waves of excitation. Here we consider a novel topological configuration in which a closed filament loop, known as a scroll ring, is threaded by a pair of counter-rotating filaments that are perpendicular to the plane of the ring and end on the boundary of a thin medium. We simulate the dynamics of this threaded ring (thring) in the photosensitive Belousov-Zhabotinsky excitable medium, using the modified Oregonator reaction-diffusion equations. These computations reveal that the threading topology induces an exotic motion in which the thring swims in the plane of the ring. We propose a light templating protocol to create a thring in the photosensitive Belousov-Zhabotinsky medium and provide experimental confirmation that this protocol indeed yields a thring.