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DY: Fachverband Dynamik und Statistische Physik
DY 57: Poster - Diffusion
DY 57.10: Poster
Thursday, March 19, 2015, 16:00–18:00, Poster A
Active Brownian micro-swimmers in viscoelastic media — •Juan Ruben Gomez Solano1,2 and Clemens Bechinger1,2 — 12. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — 2Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany
The motion of many natural micro-swimmers, such as bacteria and spermatozoa, commonly takes place in viscoelastic fluids or in complex crowded environments. The understanding of their swimming mechanisms has triggered a lot of experimental and theoretical work in recent years as well as the development of artificial self-propelled macro- and micro-swimmers. Although the motion of artificial swimmers in Newtonian fluids has been extensively studied, only few works have focused on active swimmers in viscoelastic media. In this work, we experimentally investigate the motion of spherical Janus particles in a critical binary viscoelastic fluid. The particles are self-propelled by local demixing of the fluid induced by laser illumination. We find that, unlike active Brownian motion in a Newtonian fluid, the rotational diffusion coefficient of a particle moving in a viscoelastic fluid dramatically increases with increasing particle velocity. This gives rise to a significant increase of the effective translational diffusion coefficient of the active particles with increasing laser illumination compared to the Newtonian case, which can be interpreted as an enhanced micro-swimming mechanism.