Abstract

The world of micro-organisms is filled with a variety of different swimming mechanisms which provide us with great insight into optimal propulsion at low Reynolds numbers. One example of such a mechanism is the beating of eukaryotic cilia. In the first part of the talk, we will look at the fabrication and light-actuation of a thermoresponsive polymer gel spiral which allows it to mimic cilia and to deform in a periodic but a non-reciprocal way. The breaking of the time-reversal symmetry produces a torque on the ribbon immersed in a fluid and the ribbon rotates. After introducing the experiments, done in collaboration with the group of Ahmed Mourran from Aachen, a simple mathematical model for the motion of this micro-motor will be presented, able to produce excellent agreement with the experimental data. The hydrodynamic interaction between two such micro-motors is the motivation for the work presented in the second part of this talk where we consider a pair of cilia confined between two flat, parallel walls and investigate their synchronisation. Theoretical results will provide us with a measure of robustness towards confinement of two widely accepted mechanisms for cilia synchronisation – elasticity and force modulation.