Collective beating of artificial microcilia

TL;DR

This paper investigates the collective dynamics of artificial microcilia driven by magnetic fields, revealing symmetry breaking and structural evolution influenced by array geometry and hydrodynamic interactions.

Contribution

It introduces a novel experimental setup with microcapets of magnetic rods and develops a minimal model to explain collective cilia behavior.

Findings

Symmetry breaking in collective beating patterns.

Trajectories become anisotropic with increased frequency.

Global array geometry influences cilia motion via hydrodynamics.

Abstract

We combine technical, experimental and theoretical efforts to investigate the collective dynamics of artificial microcilia in a viscous fluid. We take advantage of soft-lithography and colloidal self-assembly to devise microcapets made of hundreds of slender magnetic rods. This novel experimental setup is used to investigate the dynamics of extended cilia arrays driven by a precessing magnetic field. Whereas the dynamics of an isolated cilium is a rigid body rotation, collective beating results in a symmetry breaking of the precession patterns. The trajectories of the cilia are anisotropic and experience a significant structural evolution as the actuation frequency increases. We present a minimal model to account for our experimental findings and demonstrate how the global geometry of the array imposes the shape of the trajectories via long range hydrodynamic interactions.