Influence of swimming strategy on microorganism separation by asymmetric obstacles

TL;DR

This study investigates how different swimming strategies of microorganisms affect their separation efficiency in asymmetric obstacle arrays, emphasizing the importance of individual dynamics and geometrical optimization for enhanced sorting.

Contribution

It demonstrates through numerical simulations that microorganism rectification efficiency depends on detailed swimming dynamics and optimized obstacle geometry, enabling strategy-based sorting.

Findings

Run length distribution impacts rectification efficiency.

Rotational diffusion influences microorganism separation.

Optimized pillar geometry enhances sorting performance.

Abstract

It has been shown that a nanoliter chamber separated by a wall of asymmetric obstacles can lead to an inhomogeneous distribution of self-propelled microorganisms. Although it is well established that this rectification effect arises from the interaction between the swimmers and the non-centrosymmetric pillars, here we demonstrate numerically that its efficiency is strongly dependent on the detailed dynamics of the individual microorganism. In particular, for the case of run-and-tumble dynamics, the distribution of run lengths, the rotational diffusion and the partial preservation of run orientation memory through a tumble are important factors when computing the rectification efficiency. In addition, we optimize the geometrical dimensions of the asymmetric pillars in order to maximize the swimmer concentration and we illustrate how it can be used for sorting by swimming strategy in a long array of parallel obstacles.