在微管道晶片中，精確調控流體的混合比例是一項重要的功能，其可應用在樣本稀釋、試劑合成、藥物調配、食品精調等方面，因此本研究的動機與目的就是希望能以很簡單的方法完成微管道中調控流體混合比例的需求。學生從過去文獻中所探討的三維交錯微管道流場特性，得知管道深寬比（aspect ratio）對入口兩道流體轉向比例會有顯著的影響，故在本文中將此轉向特性加以延伸，藉由改變管道深寬比與下游管道阻力來達到調控混合比例之目的。
由CFDRC數值模擬軟體對各種深寬比與右管對下管阻力比的管道進行測試之後得知：當管道深寬比大於1或小於0.1，改變阻力比會明顯影響下游出口的混合比例；而當管道深寬比等於0.45時，混合比例卻幾乎不受阻力比所影響。
憑藉著上述的結果，學生建構出在右側主管加上多個側邊出口的概念，藉由依序關閉側邊出口來達到增加阻力比的效果，如此可使混合比例從0.1、0.2依序增加到0.9。研究中並使用數值模擬工具配合流體阻力公式來得到最佳化之管道設計。管道的製作是以黃光微影製程建立管道母模，再利用PDMS對母模進行翻模完成實驗用之調控混合比例晶片。實驗方法是使用ImageJ影像處理軟體對螢光顆粒計數及染料光強度的結果進行分析來得知混合比例。從實驗數據可以看出設計完成的晶片確實可以簡單的利用堵塞出口的方法，精確有效的控制出口混合比例。
研究後期學生進行了將調控混合比例管道結合混合器的設計，如此可讓出口具一定混合比例的產物變成均勻混合的濃度液。學生希望結合混合器的設計概念可以使本研究的內容更加完備，且適於整合在各種實驗室晶片中，成為具流體輸送、控制、混合的功能性微元件。

How to exact control the mixing ratio of fluid in microchannel is one of the most important issue in microfluid chip. The controlled mixing fraction of fluid can be used to reach the function of sample dilution, synthesis reagents, drug deployment and so on. Therefore, the main purpose of this study was to precise control the mixing fraction of fluid by regulating a simple 3-D crossing microchannel. From the past literatures, which have shown that the aspect ratio and the resistance of channel have significant effect on the fraction of turning flow in 3-D crossing microchannel. By the feature of flow turning and we designed different resistances of the downchannel, the desired mixing ratio may received from the expected outlet of channel.
From the numerical results of CFDRC, it can be found that when AR>1 or <0.1, the mixing ratio has significant related to the resistance ratio of the downchannel. However, if the AR=0.45, the resistance ratio of channel showed very little influence on the mixing ratio.
Therefore, by varying the outlets of the right downchannel with open or close mode, one may make the mixing ratio changes from 0.1, 0.2 to 0.9. In addition, the formula of fluid resistance was used to obtain the optimal design and some experimental results were realized to verify the fluid phenomena. The results of experiment showed well agree with the numerical ones.
Furthermore, a well-uniform mixing fluid can be obtained just combining the designed channel with the 3-D crossing micromixer. The combined design can be expected useful to realize the multi-function of fluid controlling, transportation and mixing to a single chip.

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