5 research outputs found
Swimming in a crystal
We study catalytic Janus swimmers and Escherichia coli bacteria swimming in a
two-dimensional colloidal crystal. The Janus swimmers orbit individual colloids
and hop between colloids stochastically, with a hopping rate that varies
inversely with fuel (hydrogen peroxide) concentration. At high fuel
concentration, these orbits are stable for 100s of revolutions, and the orbital
speed oscillates periodically as a result of hydrodynamic, and possibly also
phoretic, interactions between the swimmer and the six neighbouring colloids.
Motile E.~coli bacteria behave very differently in the same colloidal crystal:
their circular orbits on plain glass are rectified into long, straight runs,
because the bacteria are unable to turn corners inside the crystal