Document Type : Article
Authors
School of Mechanical Engineering University of Tehran
Abstract
Different studies show that at least half of the couples referring for infertility investigation and treatment have a causative male factor. Male factor infertility can be caused by a variety of defects, e.g., abnormal sperm amount, morphology abnormality, or low functionality. In all cases where the sperm cannot reach the ovum, Iin Vitro Fertilization (IVF) technique can be used for fertility. Separation of motile sperms from non-motile ones is essential in some infertility treatments such as intracytoplasmic sperm
injection ( ICSI) and in vitro fertilization. Motility is one of the most important parameters in sperm quality, the effective and safe operations are more desirable in such treatments. The ideal sperm separation technique should be easy, low-cost, separate many sperms as possible, not damage the sperms, not cause physiological transformation, eliminate dead sperms and also other cells,
allow for analyzing larger volumes of ejaculates, reduce the risk of reactive oxygen species and not having toxins for spermatozoa. In addition, after the separation step, spermatozoa must be viable and be able to fertilize the egg. Sperm morphology is directly related to the successful process. A system that selects the best sperms for fertilization can help to increase the rate of birth. In addition, sperm separation is a basic step in the IVF process. Several methods for motile sperm separation have been reported, including : Sperm washing, Sperm migration, Sperm sedimentation, Filtration, Density gradient centrifugation, Sperm surface charge for sperm selection(electrophoresis \& zeta), Magnetic-activated cell sorting (MACS), Hyaluronic acid sperm binding, Raman spectroscopy, Confocal light absorption and scattering microscopy (CLASS), and Selection based on live sperm morphology. Sperm migration and movement from one point to another, is one of the sperm separation methods. Migration method, as a method to separate motile sperms, is used as an ideal experimental sperm selection method. One of the emerging systems used for motile sperm separation is sperm separation microfluidic system. among methods of motile sperm selection, the ones which use micro channels go beyond others in simplicity, user-friendliness, and similarity to the physiological environment. Among methods of motile sperm selection, the ones which use micro channels go beyond others in simplicity, user-friendliness, and similarity to the physiological environment. Seo et al. (2007) designed a motile sperm sorting microfluidic system (MSMS) consisting four channels and three reservoirs. The flow in channels is created by hydrostatic pressure of columns at the liquid reservoirs. In this system, a reverse stream is flowing and only motile sperms are able to swim against the flow. In this paper, we will simulate and develop the MSMS micro fluidic device previously reported by Seo. After validation, with Seo's results, we optimize the size of micro channels. The results will be useful in sperm sorting applications. In addition, in this research, by the use of the optimized system and electrophoresis based concepts, microfluidic system, consisting of a electrostatic field and optimized TRMS system, is designed for separation and selection motile sperms.
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