Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 72: Microswimmers, Active Liquids I (joint session CPP, BP, DY)
CPP 72.7: Vortrag
Donnerstag, 19. März 2015, 17:45–18:00, PC 203
Detention times of microswimmers close to surfaces — •Andreas Zöttl1, Konstantin Schaar1,2,3, and Holger Stark1 — 1Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin — 2Robert Koch-Institut, D-13353 Berlin — 3Institut für Theoretische Biologie, Humoldt Universität Berlin, D-10115 Berlin
The locomotion of biological microswimmers such as bacteria in aqueous environments is determined by low-Reynolds-number hydrodynamics and influenced by thermal and intrinsic biological noise. In many relevant environments such as in the human body or in the ocean microorganisms swim in the presence of soft or solid boundaries. When bacteria approach surfaces they accumulate there and form aggregates such as biofilms. A key ingredient for the observed near-wall accumulation are the relatively large times the microswimmers reside at a surface before leaving the surface. Recently, the role of noise compared to hydrodynamic interaction with the surface for the dynamics of microswimmers at a surface has been discussed controversially.
In our work we study theoretically the collision of microswimmers with surfaces by including both hydrodynamic interactions and noise. We introduce a general framework to calculate their wall detention time distribution, i.e., the time they stay at the surface. We map the escape of the microswimmer from the surface to a mean-first passage problem and apply our theory to different swimmer models (pusher, puller, source-dipole swimmer). While source dipole swimmers have a reduced and pullers an increased detention time compared to a simple active Brownian particle, pushers can have both.