Regensburg 2019 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 26: Active matter I (joint session BP/CPP/DY)

DY 26.11: Talk

Wednesday, April 3, 2019, 12:30–12:45, H4

Diffusive dynamics of complex particles in active colloidal suspensions of motile algae — •Florian von Rüling and Alexey Eremin — Institute of Physics, Otto von Guericke Universität Magdeburg, Germany

We report experimental studies on the dynamics of complex passive particles in the presence of motile algae Chlamydomonas reinhardtii in thin capillaries. Employing video microscopy and particle tracking algorithm, the enhancement of the diffusion of elongated particles due to interactions with the microswimmers was explored. Depending on the number of motile algae, the translational and rotational diffusion constants of doublets of silica beads close to a solid boundary can be increased by several orders of magnitude in comparison to purely Brownian motion. At a high concentration of Chlamydomonas reinhardtii, the algae formed dense dynamic clusters at the lower capillary wall. In this state of the system, swimming and clustering algae interact with passive particles. Clustering algae can restrict both translational and rotational dynamics of the silica doublets. We explore the effect of the motion of algae in such active clusters on the dynamic of the passive silica doublets.