Por Daniela Kraft (Leiden University, The Netherlands).

Synthetic microswimmers constitute a new class of nonequilibrium model systems that hold great promise for applications and understanding the behavior of biological microswimmers. A simple experimental realization of such microswimmers are spheres half coated with platinum, that propel themselves autonomously in the presence of hydrogen peroxide. These synthetic swimmers 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]. 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]. Confining multiple swimmers further to one-dimensional environments, we find complex cooperative behavior such as a collective speed up and dynamic chain-formation and disassembly. [3] Finally, I will discuss the implications of these striking, activity-induced behaviors for the still-debated propulsion mechanism.

References:
[1] S. Ketzetzi, J. de Graaf, R. Doherty, D. Kraft, PRL 124, 048002 (2020)
[2] S. Ketzetzi, J. de Graaf, D. Kraft, PRL 125, 238001 (2020)
[3] S. Ketzetzi, J. de Graaf, D. Kraft, arXiv 2006.06384 [cond-mat.soft]

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Topic: CFTC weekly seminar
Time: Apr 29, 2021 10:00 AM Lisbon

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