BPCPPDYSOE21 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 11: Active Biological Matter II (joint session BP/CPP/DY)

DY 11.5: Talk

Monday, March 22, 2021, 12:20–12:40, BPb

Microscopic scattering of pusher particles in complex environments — •Theresa Jakuszeit¹, Samuel Bell², and Ottavio A. Croze¹ — ¹Cavendish Laboratory, JJ Thomson Avenue, CB3 0HE, Cambridge, United Kingdom — ²Laboratoire Physico Chimie Curie, Institut Curie,PSL Research University, CNRS UMR168, 75005 Paris, France

Active propulsion as performed by bacteria and Janus particles, in combination with hydrodynamic interaction at boundaries, can lead to the breaking of time reversibility. One typical example of this is the accumulation of bacteria on a flat wall. However, in microfluidic devices with cylindrical pillars of sufficiently small radius, self-propelled particles can slide along the surface of a pillar without becoming trapped over long times. This non-equilibrium scattering process can result in large diffusivities even at high obstacle density, unlike particles that undergo classical specular reflection, as in the Lorentz gas. We experimentally study the non-equilibrium scattering as well as the long-term diffusive transport of pusher-like particles by tracking wild-type and smooth-swimming mutants of the model bacterium Escherichia coli in microfluidic obstacle lattices. We relate the determined parameters of the scattering process to previously proposed models and discuss their relevance. Finally, we discuss the potential interpretation of the role of tumbles in the scattering process.