Coordinated motion of active filaments on spherical surfaces

TL;DR

This paper models coordinated active filament motion on spherical surfaces, revealing defect-driven synchronization, sphere movement, and emergent whirling behavior with metachronal waves, advancing understanding of cilia-like systems.

Contribution

It introduces a simulation of hundreds of active filaments on spheres, demonstrating defect-influenced synchronization and sphere motion, which was not previously modeled.

Findings

Filaments synchronize around defects on spheres.

Sphere movement results from filament beating.

Emergence of whirling state with metachronal waves.

Abstract

Coordinated cilia are used throughout the natural world for micronscale fluid transport. They are often modelled with regular filament arrays on fixed, planar surfaces. Here, we simulate hundreds of interacting active filaments on spherical surfaces, where defects in the cilia displacement field must be present. We see synchronised beating towards or about two defects for spheres held fixed. Defects alter filament beating which causes the sphere to move once released. This motion feeds back to the filaments resulting in a whirling state with metachronal behaviour along the equator.