近年來微機電（MENS）技術迅速發展，並引發了微全分析系統
（micro total analysis system）的研究，此系統具有體積小、檢測樣品少、反應時間快等優點，再結合微製程技術便可達到減少成本的效果。
為了整合更多功能在有限的晶片面積上，不同平面的三維結構晶片是未來的發展潮流，但三維管道內的流場特性的探討在文獻上並不多見，其流場特性又足以影響數據的正確解釋，或是利用其特性來操控微管流體。
本研究探討管道設計參數（管道寬、深）與實驗參數（流量）對上下兩道流體轉向的影響，也探討上下管道斜角交叉對流體轉向的影響。研究結果發現上下管道之深寬比（aspect ratio）為影響流體轉向的主要因素，管道之深寬比愈小，流體轉向的量會增加，而上下管道之流量比與匯流夾角也會影響流體轉向至另一管道的量。
本研究之結果使我們對三維結構的管道其流場特性有進一步的了解，做為未來三維結構管道設計的一項新依據。

In the past few years, microelectromechanical systems ( MEMS ) has attracted increasing interest, and it facilitates the study of micro total analysis system ( μTAS ). The system offers several potential advantages. It requires only small volumes of samples and reagents, produces little waste, offers short reaction and analysis times, is relatively cheap, and has reduced dimensions compared with other analytical devices.
In order to integrate more capabilities into limited areas of a chip, the current trend is towards the 3D structured microchannel of different planes. However, fundamentals of the flow features of 3D microchannel are not fully understood. A better understanding of the flow mechanism is highly desired to interpret the experimental results and to provide guidance for design of microfluidic devices.
This study explored the effects on fluidic exchange due to the dimensions (width and depth ), experimental conditions (flow rate) and geometries (the cross angle of two channels) in 3D crossing microchannels. The results indicated that the flow exchange at the crossing tangential microchannels was strongly dependent on their aspect ratio. The amount of the fluidic exchange will inversely increase with the aspect ratio (depth /width). In addition, the flow rate’s ratio and the cross angle of the two fluids did also influence the amount of the fluid exchange. The conclusions in this study will benefit the designing of 3D microchannel and its operation of experiment.

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