Disrupting the wall accumulation of human sperm cells by artificial corrugation

TL;DR

This study investigates how artificial corrugation in microchambers disrupts the wall accumulation of human sperm cells, potentially improving microfluidic biomedical applications by altering cell-surface interactions.

Contribution

It introduces a novel microchamber design with petal-shaped corrugation that prevents sperm cell accumulation at boundaries, unlike smooth-walled chambers.

Findings

Corrugated boundaries reduce sperm wall accumulation

Sperm trajectories are intermittent, involving quasi-circular and linear segments

Artificial corrugation alters cell-surface interaction dynamics

Abstract

Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells $60 \mu m$ long, strongly confined to $25 \mu m$ shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine.