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BP: Fachverband Biologische Physik
BP 7: Active Fluids and Microswimmers (joint session DY/BP/CPP)
BP 7.9: Vortrag
Montag, 18. März 2024, 17:30–17:45, BH-N 243
Run-and-tumble motion of ellipsoidal swimmers — •Gordei Anchutkin1, Viktor Holubec2, and Frank Cichos1 — 1Molecular Nanophotonics Group, Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany — 2Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, CZ-180 00 Praha, Czech Republic
The characteristic motion of bacteria, the so-called "run-and-tumble" motion, is a hallmark of living active particles. It consists of a sequence of linear directional movements and random rotations that constantly alternate based on a biochemical feedback process. In contrast to bacteria, synthetic active particles do not exhibit run-and-tumble motion, except they are forced to do so by sophisticated optical control feedback loops.
In this study, we show that self-thermophoretic Janus ellipsoids can carry out run-and-tumble-like dynamics under strong confinement. Our Janus ellipsoids are propelled along the short axis and exhibit long periods of directed motion before reversing the propulsion direction. We show that a bimodal out-of-plane angular distribution arises at high propulsion velocities, which is mainly the result of hydrodynamic wall interactions. We evaluate hydrodynamic interactions, and gravitational and optical forces to give a quantitative model of the observed dynamics. These interactions together with the slow rotational diffusional dynamics around the short ellipsoid axis provide the basis of the run-and-tumble dynamics.
Keywords: run-and-tumble; ellipsoids; confinement; hydrodynamics of microswimmers