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The defense date of the thesis is 2014-09-15
The current date is 2019-03-21
This thesis will be accessible at 2019-09-15
URN etd-0915114-004359 Statistics This thesis had been viewed 834 times. Download 2 times. Author Ying-yi Hsieh Author's Email Address No Public. Department Mechanical Engineering Year 2013 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 60 Title The Effects of Size, Frequency and Electrode Shape on the Collection Patterns of Micro-Particles via a 2D Electroosmosis Chip Keyword frequency electroosmosis particle size electrode shape electrode shape particle size electroosmosis frequency Abstract The collection and manipulation of small objects is important in bioassays. One commonly used force to manipulate small objects is electroosmosis which has the advantages of easy fabrication and small power consumption. Many factors affect the electroosmosis like surface charge density, applied voltage and frequency. For ac electroosmosis, frequency affects flow pattern and particle collection. A planar electroosmosis chip is fabricated by patterned electrode with circular and rectangular electrode shape. Different size latex particles (0.5μm, 1μm, 2μ m, 3μm) were used to investigate the effects of particle size and different frequencies were applied to observe the collection patterns. To further understand the mechanisms, numerical simulations via finite element software Comsol were carried out to explore the effects of particle size, operation frequency and electrode shape on the collection patterns.
The results show that in low frequency (100Hz), the particles are concentrated along the positive electrode and scatted on the negative electrode. As the frequency increases to 500 Hz and 2000 Hz, the particles on negative are less while the aggregation on the positive remains the same. As the frequency increase to 5000 Hz, the particles are concentrated into a small region instead of a long stripe. The mechanism is explored via simulation where the coupling effect of the electric field and fluid movement is considered. It is found that the fluid field induced by electroosmosis is the primary effect that influence the collection pattern. The streamline which is sensitive to the change of frequency affects the particle movement and the aggregation. The other factor like electrode shape is less important even though the pattern is different. The smaller particle is more difficult to aggregate due to the buoyance effect. It is shown that electroosmosis is frequency-control and by varying frequency the concentration pattern can be changed accordingly.
Advisor Committee Che-hung Wei - advisor
Chu-shou Yang - co-chair
Min-sheng Hung - co-chair
Files Date of Defense 2013-07-24 Date of Submission 2014-09-15