Sperm-like-particle (SLP) behavior in curved microfluidic channels

Microfluidic technology has the potential to separate sperm cells from unwanted debris commonly found in clinical samples while improving the effectiveness of assisted reproductive technologies. In this study, we present an improved model of sperm cell behavior in curved channels based on both 2D COMSOL^® simulations and experimental studies. The 2D COMSOL^® simulation results show alignment of the sperm like particles, which suggests that sperm should be treated as small, relatively stationary particles rather than larger rotating particles. This understanding helps us generate more precise sperm separations for µTESE samples by enabling the assumption of a small particle rather than a large one. This alignment was also confirmed by observing the alignment angle of all recognizable sperm cells with high-speed imaging near the outlet area of the spiral channel. A series of experiments with sperm cells and microbeads showed clear separation improvement between the new experimental conditions and previous efforts. Sperm were found to behave more similarly to 3 µm beads than to 5 µm beads and that sperm cells may act like particles even smaller than the 3-µm beads. The focused sperm cell stream appeared in the middle area of the channel and the focused RBCs stream appeared at the mid-inner wall area of the channel. Basic biocompatibility testing also suggests that the approach can be used safely in a clinical setting.