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Design and Fabrication of Microfluidic Chip for Selection of Functional Sperm

Ahmadkhani, Nima | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53508 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Saadatmand, Maryam; Abdekhodaie, Mohammad Jafar; Kazemnejad, Somaieh
  7. Abstract:
  8. Infertility is a growing global issue with significant psychological, economic, and social consequences, which among them, male factor infertility problems make up a considerable portion. The conventional methods of sperm separation inclusive of density-gradient centrifugation and swim-up with numerous problems contain DNA fragmentation and low yield, and both of the methods are not effective for samples with low sperm counts. Modern microfluidic systems are trying to improve this problem by increasing the quality of the isolated sperms. However, most of these systems rely solely on sperm motility as a separation mechanism, which is not a sufficient condition for the separated sperm to be healthy. Therefore, researchers have focused on other aspects of the biological simulation of the female reproductive tract on microfluidic systems. The purpose of this study was to enhance the quality of sperm isolated by a microfluidic chip with the biological simulation of the mechanism of rheotaxis, which was recognized as the dominant mechanism in the female reproductive system. In fact, this mechanism is based on the response of sperms to the upstream flow, which occurs as a result of asymmetry in the geometry of the sperm head and tail, and causes the sperm to move in the opposite direction of flow. In this regard, after fluid simulation of microfluidic chip channels inclusive of linear, square, zigzag, and asymmetric curved channels by COMSOL software, microfluidic mold and final system got a design by a photolithography method and soft lithography using poly (Dimethyl siloxane), respectively. Image analysis of sperm motion in the linear channel, unlike other channels, showed that sperms rarely encountered the present maximum flow velocity in the center of the channel. In square and zigzag geometries, occasionally observed accumulation in the corners of the channels which caused obstruction in the sperm path. The decrease in the number of sperms in the channels as they approach the outlet indicates the ability of a few sperms to make their way to the outlet. motility analysis resulted by CASA software that non-progressive sperms were able to make their way to linear channel outlet. Approximately 19% of sperms contained in this outlet were reported without non-progressive motility, which is less than 10% for other geometries. The 100% sperm motility reported by CASA software indicated 100% sperm viability in all outlets. Significant improvement in sperm morphology was indicated in various channels in the comparison of raw semen. In asymmetric curved geometry, sperm morphology improved more than 3-fold that had a proper performance than other channels
  9. Keywords:
  10. Microfluidic Chip ; Infertility ; Sperm Separation ; Sperm Swimming ; Rheotaxis Mechanism

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