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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 57: Complex Fluids and Colloids, Micelles and Vesicles II (joint session CPP/DY)

CPP 57.1: Invited Talk

Friday, March 31, 2023, 09:30–10:00, MER 02

Chiral transport of active and passive colloids — •Anke Lindner1, Andreas Zöttl2, Olivia du Roure1, Eric Clement1, Francesca Tesser1, and Guangying Jing31PMMH-ESPCI, 10, rue Vauquelin, 75011 Paris, France — 2Faculty of Physics, University of Vienna, Kolingasse 14-16, 1090 Wien, Austria — 3School of Physics, Northwest University, Xi'an, 710127, China

Chirality-induced effects are at the origin of bacterial rheotaxis and particle drift in shear flows. Here we investigate such effects using a combination between experiments and theoretical modeling for two systems: E-coli bacteria and 3D printed micro-particles.

The micro-particles consist of a spherical head and a helical tail of different pitch and handedness. We investigate the chirality-induced reorientation dynamics using microfluidics and observe asymmetric orientation bistability perpendicular to the flow direction. We quantitatively explain our findings through a theoretical model without adjustable parameters considering particle elongation, chirality and head-heaviness, in very good agreement with experiments.

We then present a study of the transport of motile bacteria in shear flows. Experimentally, we obtain with high accuracy and for a large range of flow rates, the spatially resolved velocity and orientation distributions. They are in excellent agreement with the simulations of a kinematic model accounting for stochastic and microhydrodynamic properties and flagella chirality. In contrast to the micro-printed particles Brownian rotational noise plays a crucial role in bacterial rheotactic drift.

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