Swimming In a Crystal

We study catalytic Janus particles and Escherichia coli bacteria swimming in a two-dimensional colloidal crystal. The Janus particles 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.

Brown, Aidan T.; Vladescu, Ioana D.; Dawson, Angela; Vissers, Teun; Schwarz-Linek, Jana; Lintuvuori, Juho S.; Poon, Wilson C. K.. (2015). Swimming In a Crystal, 2013-2015 [dataset]. University of Edinburgh, School of Physics and Astronomy, Institute of Condensed Matter and Complex Systems. http://dx.doi.org/10.7488/ds/304.