Analysis and Simulation on the Relationship between Aspect Ratio and the Velocity Distribution Induced by the EOF Phenomenon Using CFDRC

In the detection of biomedical and biochemistry, the microfluidic chips play an important role. In order to improve the efficiency for the detection, the investigation on the velocity field must is a must. Because the different aspect ratio and the different material of the microchannel could change the velocity field, then the detecting efficiency of the microfluidic chips could be affected. Therefore, the objectives of this research were (1) to model the velocity field caused by electroosmotic flow in the rectangular microchannel, (2) to fix the cross-section area value and alter the aspect ratio of the microchannel to study the variation of the velocity field, and (3) to change the material of the bottom channel wall, and to study the variation in the microchannel associated with different aspect ratio at a fixed value of cross-section area. According to results of both the numerical simulation and experiment, in the rectangular microchannel that each channel wall was built of the same material, the velocity field in the microchannel was maining influenced by the zeta potential on the channel wall but not to the aspect ratio. In the rectangular microchannel which the material of bottom channel wall was varied to others, the zeta potential was still a major influence, however the velocity field was also influenced by the area of the bottom channel wall. In addition,for the bottom channel wall using different material to others, the result showed that the distance (Hi), which influenced by zeta potential in the velocity field on the bottom channel wall, was equal to the width of the bottom channel wall (W).在生醫生化檢測上，微流體晶片扮演著重要的角色，為增進其檢測效率，有必要對微管道中之流場進行研究，因為不同微管道高寬比與不同管道基材的結合，有可能致使管道內之流場產生變化，而影響微流體晶片之檢測品質，故本研究之目的為（1）針對矩形微管道中電滲流（electroosmotic flow, EOF）之流場進行模擬；（2）固定矩形微管道之截面積，改變微管道之高寬比，探討矩形微管道中之流場之變化；及（3）改變微管道底面管壁之材質，討論相同截面積但不同高寬比對矩形微管道內流場分佈之影響。 由軟體模擬配合實驗之結果顯示，在管壁材質均相同的矩形微管道中，管道內之流場，主要是受到管壁上zeta potential（ζ電位）的影響，高寬比對於流場則幾無影響；在底面管壁材質不同的矩形微管道中，管壁上之zeta potential仍為主要的影響因子，但微管道內之流場變化亦會隨著不同材質之底面管壁的面積大小而有所改變。另外，研究結果顯示，不同材質之底面管壁，其zeta potential在流場內所能影響之距離（Hi）約等同於底面管壁之寬度（W）。摘要 vi Abstract vii 目 次 viii 表 目 次 xi 圖 目 次 xii 符號表 xv 第1章 緒論 1 1.1 前言 1 1.2 研究目的與項目 2 第2章 文獻探討 3 2.1 微流體晶片 3 2.2 電雙層的形成 5 2.3 電滲流的形成 7 2.4 CFD模擬軟體的應用 11 第3章 材料與方法 16 3.1 CFDRC之介紹 16 3.1.1 CFD-GEOM之介紹 17 3.1.2 CFD-ACE之介紹 19 3.1.3 CFD-VIEW之介紹 20 3.2 基本假設 20 3.3 理論基礎 21 3.3.1 電雙層分佈 21 3.3.2 外加電場之電位勢分佈方程式 22 3.3.3 流體運動方程式 22 3.4 實驗參數與方法 23 3.4.1 模擬實驗參數 23 3.4.2 初始、邊界條件 27 3.5 微管道之製作 29 3.6 電滲流量測方法 35 第4章 結果與討論 41 4.1 模擬結果與實驗結果之比對 41 4.2 A型與B型管道之流速比較 44 4.3 高寬比對流場之影響 46 4.3.1 高寬比對A型管道流速之影響 46 4.3.2 高寬比對B型管道流速之影響 47 第5章 結論 58 參考文獻 6