A microfluidic method for passive trapping of sperms in microstructures

TL;DR

This paper introduces a passive microfluidic method that passively traps motile sperm cells in microstructures, significantly increasing their local concentration without external forces, aiding reproductive technologies.

Contribution

The study presents a novel passive trapping technique using microstructured devices that enhances motile sperm concentration, validated through experiments and simulations.

Findings

Approximately 10-fold increase in sperm concentration in traps

Enhanced contrast between motile and non-motile sperm by similar factor

Simulation results align with experimental observations

Abstract

Sperm motility is a prerequisite for male fertility. Enhancing the concentration of motile sperms in assisted reproductive technologies - for human and animal reproduction - is typically achieved through aggressive methods such as centrifugation. Here we propose a passive technique for the amplification of motile sperm concentration, with no externally imposed forces or flows. The technique is based upon the disparity between probability rates, for motile cells, of entering in and escaping from complex structures. The effectiveness of the technique is demonstrated in microfluidic experiments with microstructured devices, comparing the trapping power in different geometries. In these micro-traps we observe an enhancement of cells concentration close to 10, with a contrast between motile and non-motile increased by a similar factor. Simulations of suitable interacting model sperms in realistic geometries reproduce quantitatively the experimental results, extend the range of observations and highlight the ingredients that are key to optimal trap design.