Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 46: Microswimmers (joint session BP/CPP/DY)

DY 46.8: Vortrag

Mittwoch, 14. März 2018, 17:00–17:15, H 1028

Altering diffusion by interaction of microalgae with micron-sized objects — •Francine Kolley^1,2, Patricia Dähmlow², Hajnalka Nadasi², Florian von Rüling², and Alexey Eremin² — ¹Technical University Dresden — ²Otto-von-Guericke-University Magdeburg

The enhancement of passive particles, single silica spheres and their doublets, was studied in suspensions containing microswimmers Chlamydomonas reinhardtii. These green algae move with a flagellar motor, reaching typical velocities up to 150 μm/s. Stimulated by phototaxis, their motion is similar to humans doing breaststroke. The induced flow of the puller affects the translational as well as the rotational diffusion of the passive particles. The corresponding diffusion coefficients were obtained from the measurement of the mean square displacements of the passive particles for various concentrations of the algae. The Brownian Motion of the silica beads was observed in a quasi-2D system in flat cappilaries.To avoid cell immobilization by adsorption to the glass substrate the capillary surface was silanized. Additionally, a polymer was introduced to the suspension to optimize the diffusive behavior. In the range of small algae concentrations, the diffusion coefficients exhibited a linear dependence on the cell density of Chlamydomonas reinhardtii.