Selection of Functional Human Sperm with Microfluidic Sorting Device

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 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 - 12 μm). The top chamber is aligned and attached using a double sided adhesive to the bottom chamber, where there is a small injection point. A sperm sample is prepared by mixing raw semen sample with human tubal fluid plus 1% bovine serum albumin.The sperm sample is then injected into the bottom chamber, and after 45 minutes, a sample of sperm suspension collected from the top chamber is placed on a glass slide for visual observation at 200x magnification. We observe that (1) the larger the pore size of the filter reduces the DNA fragmentation in the sperms, which effectively leads to a higher outcome of the motility. (2) Our data show that within a range of sperm density, the average motility can reach 90-95 %. Taken together, the presented research may provide an efficient method to increase the selection of highly motile sperm, without centrifugation.