Berlin 2018 – scientific programme
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BP: Fachverband Biologische Physik
BP 8: Active Matter DY II (joint session DY/CPP/BP)
BP 8.7: Talk
Monday, March 12, 2018, 17:15–17:30, BH-N 243
Guidance of self-phoretic Janus particles by chemically patterned surfaces — William Uspal1,2, •Mihail Popescu1,2, Mykola Tasinkevych3, and Siegfried Dietrich1,2 — 1M.P.I. for Intelligent Systems, Stuttgart, Germany — 2University of Stuttgart, Germany — 3University of Lisbon, Portugal
Self-phoretic Janus particles move by inducing -- via non-equilibrium chemical reactions occurring on their surfaces -- gradients in chemical composition along the surface of the particle, as well as along any nearby boundaries. The chemical gradients along a wall can give rise to chemi-osmosis, which, in turn, drives flow in the volume of the solution and thus couples back to the particle. This response flow induced and experienced by a particle encodes information about any chemical patterning of the wall. Here, we show by analytical calculations, complemented with numerical solution, that wall-patterning by chemical steps can provide the means for docking of achieving a step-guided motion of such an active particle, and we discuss the dependence of the phenomenology on the shape (spherical or rod-like) of the particle. Furthermore, we show that such chemically active particles in general align with, and follow, spatial gradients in the surface chemistry of the wall (i.e., they exhibit thigmo-taxis).