Development of Microfluidic Device Operated by Hydrostatic Pressure for Sorting Motile Sperm

The first step of in-vitro fertilization is to sort out the motile sperms from the non-motile ones.In this work, we construct a sorting device based on microfluidic principles and hydrostatic pressure and explore its efficiency in selecting highly motile sperm.The sperm sorting device consists of two chambers (top and bottom),separated by a polycarbonate filter with pores of a particular size (5-12μm).The top chamber is aligned and attached to the bottom chamber, where there are two small points.The hydrostatic pressure can generate the flow in the bottom chamber.The sperm sample is injected into the bottom chamber.After 45 minutes, a sample of sperm suspension collected from the top chamber is placed on a glass slide for visual observation.We observe that (1)the larger the pore size of the filter reduces the DNA fragmentation in the sperms.(2)Our data show that within a range of sperm density, the average motility can reach 90-95%.(3)The flow rate 27μL/min gives the highest concentration of motile sperm and the lowest DNA fragmentation.(4)Our design allows a much larger pressure difference which is easier to use in clinical laboratory.Taken together, the presented research may provide an efficient method to increase the selection of highly motile sperm, without centrifugation.