重力、表面張力及表面粗糙度對微流體流動時間影響之研究

隨著電子、生醫、通訊及航太等科技的進步，工程科技界莫不努力探求並試圖掌握尺度的最小極限，使得細微加工技術之尺寸由傳統的毫米階段進步到微米、奈米的階段，大量增加了高附加價值與高產值產品的需求，且由於微小系統能廣範應用於半導體、生醫、化學、能源、光電等產業，微生醫、覆晶底膠充填與微流體領域受到重視，由毛細現象所導致的充填問題、驅動原理及液體流動的控制，都變得相當的重要。本研究基於如此的動機與目的，進行微流道內液體之毛細流動現象及時間的探討。本文主要針對微流體流動時間的理論作推導，探討在重力及毛細力共同驅動下之微流體流動時間及流動狀態，並將模型簡化為一維的流動狀態，以那維爾－史托克斯方程式作為基礎，推導出其流動時間方程式；接著搭配不同間隙高度實驗模型，透過改變儲液槽內流體高度進行微流體的流動實驗，探討重力與毛細作用力的影響力，並將實驗結果與理論推導之流動時間相互比較驗證。由結果顯示，兩者之間有很好的一致性，且隨著微流道間隙越小時，重力的驅動力對流動時間的影響則越不明顯，即在越微小間隙的流道中毛細力成為驅動液體運動的主要動力來源；接著針對不同粗糙度表面對微流體流動時間的影響作研究，利用二氧化碳雷射雕刻、微輪磨加工及SU-8光阻製程，分別加工出細切面(粗糙度值2.0~6.3微米)、精切面(粗糙度值0.25~1.6微米)及超光面(粗糙度值0.01~0.20微米)之壓克力平板流道，透過改變儲液槽內流體高度使重力產生變化來進行微流體的流動實驗，以探討粗糙度對微流體流動時間的影響。由結果顯示粗糙度值越大，微流體的流動速度越快，而其波前越不穩定，且隨著重力驅動力的增加，不同粗糙度模型之間流動時間差距越大。

關鍵字

毛細現象；那維爾－史托克斯方程式；微流體；表面粗糙度

並列摘要

Due to the great advancement in fields of electron, biomedical, communication and aerospace technology, the size in micromachining technology has progressed from millimeter to micrometer and even to nanometer by increasing demands of high added value and high output products. In addition, the micro system can be applied in many industries such as semi-conductor, bio-medical, chemical, energy and photoelectric industries. Therefore, the filling behavior, driving principle, and control of flowing caused by capillarity phenomena become crucial. In this paper, flows in rectangular microchannels driven by capillary force and gravity are discussed. The theoretical mathematical model of flow in microchannel driven by capillary force and gravity is formulated from the Navier-Stokes Equations. A close form solution to predict flow time was developed, and experiments have been performed to investigate and verify the flow times in microchannel. From the results, the predicted flow times show reasonably good agreement with the corresponding experimental flow times. Moreover, when the microchannel height is small, the effects of gravity force becomes less obvious, namely the capillary becomes the dominate source to drive microfluidic. Besides, the influence of surface roughness in microchannel is studied, and three different methods of machining were used to manufacture those microchannels, and experiments have been performed to investigate and verify the flow times in microchannel. From the results, the surface roughness increased, then the flow time is less, and the flow-front of microfluidic becomes more unsteady.

並列關鍵字

Surface Roughness ； Microfluidic ； Capillary Phenomena ； Navier-Stokes Equation

參考文獻

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重力、表面張力及表面粗糙度對微流體流動時間影響之研究

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