Collective beating of artificial microcilia
  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. 
Na\"is Coq, Antoine Bricard, Francois-Damien Delapierre, Laurent   Malaquin, Olivia du Roure, Marc Fermigier and Denis Bartolo
cond-mat.soft physics.flu-dyn