Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 44: Aktive Matter I (joint session DY/BP/CPP, organized by DY)

CPP 44.4: Vortrag

Mittwoch, 22. März 2017, 15:45–16:00, HÜL 186

Synthetic Janus microswimmers moving under confinement in viscoelastic media — •Juan Ruben Gomez Solano1, Mahsa Sahebdivani1, and Clemens Bechinger1,212. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — 2Max-Planck-Institut fuer Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany

The motion of many natural microswimmers, e.g. bacteria and spermatozoa, commonly takes place in viscoelastic media and under confinement close to solid walls. Recent experiments demonstrate that active colloids in Newtonian liquids can be hydrodynamically and phoretically trapped or guided by solid walls depending on the surrounding flow field and on the geometry of the confinement [1-3]. In our work, using spherical Janus microswimmers activated by light in a semidilute polymer solution [4], we experimentally investigate how viscoelasticity affects the motion of such self-propelled particles when approaching or leaving a flat wall. Unlike self-propulsion in Newtonian fluids, we find a strong particle-wall repulsion induced by the surrounding viscoelastic liquid over large distances from the wall. We show that this phenomenon has dramatic consequences for the particle translational and rotational dynamics in more complex confined geometries, as well as for collective motion in crowded environments.

[1] G. Volpe et al., Soft Matter 7, 8810 (2011). [2] D. Takagi et al., Soft Matter 10, 1784 (2014). [3] J. Simmchen, Nat. Comm. 7, 10598 (2016). [4] J. R. Gomez-Solano, A. Blokhuis, and C. Bechinger, Phys. Rev. Lett. 116, 138301 (2016).

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