Rheotaxis-based sperm separation using a biomimicry microfluidic device

Abstract

Sperm selection is crucial to assisted reproduction, influencing the success rate of the treatment cycle and offspring health. However, in the current clinical sperm selection practices, bypassing almost all the natural selection barriers is a major concern. Here, we present a biomimicry microfluidic method, inspired by the anatomy of the female reproductive tract, that separates motile sperm based on their rheotaxis behavior to swim against the flow into low shear rate regions. The device includes micropocket geometries that recall the oval-shaped microstructures of the female fallopian tube to create shear protected zones for sperm separation. Clinical tests with human samples indicate that the device is capable of isolating viable and highly motile sperm based on their rheotaxis responses, resulting in a separation efficiency of 100%. The device presents an automated alternative for the current sperm selection practices in assisted reproduction.

Disposable paper-based microfluidics for fertility testing

“…Additionally, a 14% decrease in ROS was observed as a result of the use of nanodiamond particles. Similarly, to improve sperm sorting applications for ARTs, a microfluidic device that mimics the female reproductive tract and separates sperm cells based on rheotaxis response to flow environments was created ( Sarbandi et al., 2021 ).…”

A Review of the Impact of Microfluidics Technology on Sperm Selection Technique

“…A known long-range process is the rheotaxis mechanism, in which sperm move up against a flow, while thermotaxis and chemotaxis are short-range means [46][47][48]. Similarly, Zaferani et al used a microfluidic tool that is not harmful and can inactively differentiate active spermatozoa from semen fluid using the rheotaxis behavior of sperm [49].…”

Lab on a chip devices for fertility: from proof-of-concept to clinical impact

“…31 Inspired by the anatomy and rheological properties of the female reproductive tract, devices have been developed that use diffuser type microgeometries to select motile sperm by providing favourable shear zones (shear rates of 2 to 5 s −1 ) for sperm rheotaxis. [32][33][34] These methods can select sperm with considerably improved progressive motility, normal morphology and DNA integrity, [32][33][34] Silicon-glass 19 • Outperforming clinical selection methods in side-by-side testing Cutting using a cutting plotter 22,23 Polyethylene/polyester films 22,23 • Offering standardization and automation at low-cost 3D printing 24 Surgical guide resin 24 39 improve fertilization rate and early embryo development rate after intracytoplasmic sperm injection (ICSI) in mice (compared to sperm selected using swim-up). 35 However, low retrieval rate, complexity in operation, and/or sample dilution due to added buffer have limited the application of these rheotaxis-based sperm selection methods.…”