AbstractMotility is one of the most important factors in sperm migration toward egg. Therefore, sperm separation based on motility increases the chance of the best sperm selection in the process of infertility treatments. Unfortunately, it is now vastly done by conventional procedures which lack certain delicacy and precision and increase the risk of damage to sperm cells. Microfluidic systems, on the other hand, can sort sperm in a less intrusive way. However, microfluidic techniques have yet to receive widespread adoption in clinical settings, not only due to their relatively cumbersome operation, but also their extremely low outcome, leaving them inefficient in practice. Here we propose a microchamber-based microfluidic platform that can separate progressive motile sperm from nonviable sperm and debris as well as trapped nonprogressive sperm in the microchambers. Our platform is operated in a short period of time (<10 min) with an excellent degree of controllability, without any prior sample preparation. Our results show that the microchambers’ depth does not affect the residence time of motile sperm. Therefore, we are able to inspect high sample volumes (1 mL) within the same time. Furthermore, we maximize the concentration of the collected sperm by tuning the washing medium flow rate above the sperm rheotactic threshold. We foresee that our microfluidic platform may provide a facile solution for high-throughput, robust, and easy-to-modify for collection of progressive sperm needed for assisted reproductive technologies (ARTs).Significance StatementAssisted Reproductive Technologies require efficient, minimally invasive, and fast methods of sperm separation. Centrifugation methods used in clinics and biological research labs, fall short in these aspects as they are low-yield, intrusive to sperm’s DNA, and time consuming. We have developed a microchamber-based microfluidic platform for high-throughput separation of progressive motile sperm from undiluted raw semen samples. The method was further optimized to increase the concentration of collected samples. Higher concentration of collected samples combined with higher motility of the separated sperm compared to those in raw semen, make it a suitable choice in clinical applications, fertility diagnostics, and fundamental research.
FertDish: microfluidic sperm selection-in-a-dish for intracytoplasmic sperm injection
