Micro diffuser-type movement inversion sorter for high-efficient sperm sorting

In this study, we propose a microfluidic device with a diffuser type chamber to differentiate the sperm velocity by gradually lowering down the flow speed in diffuser by gradually increasing the width of the channel. When the sperms' moving speed match the flow speed, the sperms tend to have the ability to flow against the stream, thus separating the sperms at different specific positions along the diffuser according to their motility becomes gentle and fast. Most of the motile sperm will stay in the expanding area and the non-motile sperms will drift to outlet. Different from the previous study we proposed in IEEE NEMS, 2012, here we have three improvements: (1) Sperms can be separated in more detailed quality level. (2) Sperm will be more activated by passing through a dumb bell area than by the traditional methods. (3) The space in the device can accumulate large amount of sperms (∼millions).