Suppression of bacterial rheotaxis in wavy channels

TL;DR

This paper investigates how flow patterns in wavy microchannels influence bacterial swimming behavior, revealing a resonance effect that enables controlled deflection and suppression of surface rheotaxis, with implications for microfluidic control.

Contribution

It introduces a novel resonance effect for microswimmers in wavy channels and demonstrates how flow amplitude can control bacterial accumulation and orientation.

Findings

Resonance effect causes microswimmers to be deflected in wavy channels.

Flow amplitude can suppress upstream orientation and boundary accumulation.

Controlled swimmer behavior can be achieved in modulated microchannels.

Abstract

Controlling the swimming behavior of bacteria is crucial, for example, to prevent contamination of ducts and catheters. We show the 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. We predict a novel resonance effect for semiflexible microswimmers in flows through wavy microchannels. 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 lead to surface rheotaxis are suppressed. Our results suggest new strategies for controlling the behavior of live and synthetic swimmers in microchannels.