Quantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets

TL;DR

This study numerically investigates how asymmetric microstructures can effectively sort and separate different self-propelled microorganisms based on their motility strategies, optimizing efficiency and timing.

Contribution

It introduces a detailed numerical analysis of microorganism sorting using geometrical ratchets, highlighting how obstacle design influences separation based on swimming behavior.

Findings

Asymmetric obstacles enhance sorting efficiency.

Separation time depends on motility differences.

Effective sorting occurs even with minor behavioral differences.

Abstract

Suitable asymmetric microstructures can be used to control the direction of motion in microorganism populations. This rectification process makes it possible to accumulate swimmers in a region of space or to sort different swimmers. Here we study numerically how the separation process depends on the specific motility strategies of the microorganisms involved. Crucial properties such as the separation efficiency and the separation time for two bacterial strains are precisely defined and evaluated. In particular, the sorting of two bacterial populations inoculated in a box consisting of a series of chambers separated by columns of asymmetric obstacles is investigated. We show how the sorting efficiency is enhanced by these obstacles and conclude that this kind of sorting can be efficiently used even when the involved populations differ only in one aspect of their swimming strategy.