A microfluidic device for separating motile sperm from nonmotile sperm via inter-streamline crossings

In vitro fertilization using small amounts of cryopreserved sperm would benefit from efficient microscale methods to sort "healthy" motile sperm from nonmotile ones. This paper describes a microfluidic system with embedded reservoirs that sorts sperm based on the ability of motile sperm to move out of their initial streamlines in a laminar fluid stream. The device has horizontally oriented sample inlet and outlet reservoirs with different relative heights that serve the dual purpose of also being a pumping system that pumps fluids by hydrostatic pressure and surface tension. Sperm sorting is necessary for cryopreservation and intracytoplasmic sperm injection of sperm from men with low viable sperm counts. Since they have few viable sperm, it is difficult to obtain the sperm in an efficient manner using current procedures