Exploring Thigmotaxis and Rheotaxis Mechanisms in Sperm Cell Migration Within Different Microchannels Using Finite Element Method

Technology used in assisted reproduction is becoming more and more necessary as the number of infertile couples rises. So, a solid grasp of motile sperm migration is essential. Microfluidics has attracted the attention of assisted reproductive technology due to its numerous advantages such as simulating the natural environment of the human body, examining sperm at the micron level, high biocompatibility, and the non-invasive nature of the devices. In our study, we employed Computational Fluid Dynamics (CFD) simulations to investigate how different microchannel geometries affect sperm selection in the context of the rheotaxis mechanism. We utilized COMSOL Multiphysics software, employing the Laminar flow and transport of diluted species physics to track sperm movement in four distinct microchannel geometries: serpentine, square, zigzag, and linear. All of microchannels showed rheotaxis mechanism at a flow rate of $0.00066 \mu \mathrm{~L} / \mathrm{sec}$. While the square and zigzag channels exhibited dead zones, leading to sperm accumulation in the corners, no such dead zone was observed in the serpentine microchannel. The time required for the sperm washing is $185 \mathrm{~s}, 200 \mathrm{~s}, 165 \mathrm{~s}$, and 130 s for serpentine, square, zigzag, and straight microchannels, respectively. The results revealed that the serpentine geometry outperformed other microchannels in effectively selecting high-quality sperm.