Suppression of bacterial rheotaxis in wavy channels

Abstract

Controlling the swimming behavior of bacteria is crucial, for example, to prevent contamination of ducts and catheters. We show that bacteria modeled by deformable microswimmers can accumulate in flows through straight microchannels either in their center or on previously unknown attractors near the channel walls. In flows through wavy microchannels we predict a resonance effect for semiflexible microswimmers. As a result, microswimmers can be deflected in a controlled manner so that they swim in modulated channels distributed over the channel cross section rather than localized near the wall or the channel center. Thus, depending on the flow amplitude, both upstream orientation of swimmers and their accumulation at the boundaries, which can promote surface rheotaxis, are suppressed. Our results suggest strategies for controlling the behavior of live and synthetic swimmers in microchannels.