Slip and ypsotaxis of catalytically self-propelled particles near surfaces

Catalytically propelled microswimmers have a strong affinity for surfaces, but little is known about how surfaces affect their behavior. In this talk, I will demonstrate that the choice of the substrate material has a strong influence on the microswimmer speed through slippage [1]. Then, using a new height analysis approach, I will show that the microswimmer-wall separation is surprisingly robust for a range of salt concentrations, swimmer surface charges, and swimmer sizes [2]. These striking, activity-induced findings have furthermore important implications for the still-debated propulsion mechanism.

References:
[1] Ketzetzi, de Graaf, Doherty, Kraft, PRL 124, 048002 (2020)
[2] Ketzetzi, de Graaf, Kraft, PRL (accepted, 2020) & arXiv 2006.06384 [cond-mat.soft]