부산대학교 도서관

This study examined the performance of a microfluidic device for sperm separation assuming that X- and Y-sperm have different surface electrical charges. The proposed microfluidic chip was first tested with electrically charged particles, namely TiO 2 -coated polystyrene (PS) beads, to mimic spermatozoa. Negatively charged TiO 2 -coated PS beads were fabricated in a simple and efficient manner. These beads were characterised using X-ray diffraction, tungsten scanning electron microscopy with energy-dispersive X-ray spectroscopy mode, and X-ray absorption spectroscopy to determine the reason for the persistence of the negative surface charge. The fabricated TiO 2 -coated PS beads were partly coated in mixed forms of amorphous Ti 4+ , which caused a sustained negative charge on the surface after fabrication. The microfluidic device was simulated to obtain an optimal structure for fabrication. Negatively charged TiO 2 -coated PS beads were tested in designed microfluidic devices. Detailed structures for microfluidic device design with integrated microelectrodes were fabricated using a photolithographic technique, and the finished device was tested with PS beads. Based on PS-bead separation, a microfluidic device with a $150~\mu \text{m}$ microchannel and $100~\mu \text{m}$ distance between electrodes was the best performing prototype at 87.07% with a confidence level of 95%. Commercial positively and negatively charged PS beads were tested in the selected design for additional validation. Finally, sperm separation using the proposed device was conducted; the specially designed microfluidic device with multiwalled carbon nanotubes was fabricated, and the proposed device showed a X- and Y-sperm separation accuracy of 74.62%. [2020-0278]