The study of spermatozoa and sorting in relation to human reproduction

In this review article, we seek to provide a link between our understanding of the spermatozoa on the physical aspects and applications involving assisted reproduction, so that future research in this field can be better poised for improving current procedures. A brief discussion is included regarding the difference in the fluid mechanics of a Newtonian and viscoelastic fluid medium. A review is then done on the current microfluidic sorting techniques applicable to spermatozoa, which includes the albumin gradient separation, fluorescence activated flow cytometry, electrophoresis, dielectrophoresis, countercurrent distribution, movement of motile sperms, accumulation at walls, and optical trapping. Common preparation methods for spermatozoa used in assisted reproduction are also introduced. A number of other general particle manipulation methods which could potentially be incorporated for sperm sorting are also discussed.