Hydrodynamic interactions between artificial swimmers and obstacles

Bimetallic micro-rods swimming in hydrogen peroxide solutions are a
standard example of self-propelled particles used in a large number of
experiments. Here, we present how micro-rods can be designed to propel
like pullers, pushers or symmetric swimmers.

We combine experiments and numerical simulations to investigate the dynamics
of rods swimming around obstacles. We find that the characteristic
residence time around an obstacle is longer for symmetric swimmers
than for puller or pushers.
When the obstacles form a lattice the swimmer speed and its residence time
control the long time diffusion coefficient; for non-symmetric
obstacles the displacement bias is different for each kind of
rod. These differences suggest that microfluidic devices can be used
to sort self-propelled particles with different swimming natures.