微型流式細胞儀是近年來生醫檢測晶片熱門的發展重點之ㄧ，其優點可以快速檢測樣本內容，無論是細胞尺寸、種類等。並且，近年更有Seki之研究團隊著重於運用流體於微管道內為層流的現象，即可達到不同微粒尺寸之分離。故本研究期結合此兩種微流晶片之優點，達成可分析的自然流場樣本分離晶片。

　　微管道製作方式則是利用微機電製程，製作以polydimethylsiloxane (PDMS)與玻璃為基材之微流體系統。本研究藉由數學推導，獲得矩形管道流場速度分佈關係式，比照電壓與電阻的關係，求出適用於矩形管道的流阻公式(RA.A.D)，並與Hagen-Poiseuille equation比較，由實驗結果成功驗證本研究使用的流阻公式較適用於矩形管道。

　　本研究成功整合微流體力聚焦系統及自然流場微粒分離機制於單一微流系統，本實驗以2 μm與10 μm的乳膠微粒測試，設定640 μl/hr邊鞘流流量與40 μl/hr樣本流(2+10 μm)流量推入管道，由實驗結果可確定微粒均被聚焦至管道中央後流入主管，且流經障礙物後，由於層流擴張的現象，使2 μm與10 μm微粒產生相異的位移路徑而後分別被收集出。統計微粒分佈比例，此二種微粒在出口位置的表現上有相當的鑑別率，故本研究針對微流體聚焦系統提供了另一個有效的微粒分離機制。

　　The micro flow cytometry is an important technology for sample analysis in bio-chip science. The advantage is that bio-particles can be analyze rapidly no matter cell size or type. Among various methods, recently, the development of physical methods (without external forces) by making use of the laminar flow profile inside microchannels has drawn certain attention. In this study, we intend to integrate the above methods in our systems for separation of particles in nature flow and be used for analysis in the future.

　　First, we introduce the theories of micro-hydrodynamic focusing and particle-separation method, then prove the suitable flow resistance equation and explain the design of micro-fluidic chip. The study employed MEMS fabrication technique for building microchannel using PDMS elastomer. The master is formed on silicon wafer using an epoxy-based photoresist. PDMS is cast against the master producing molded layer containing channel then bonded on a glass to build microchannel.

　　Theoretically, by controling the flow rate at the inlet, particles will move along centerline of the channel. When particles flow through the obstacle, they follow different paths according to their sizes due to laminar flow profiles. In this study, we can separate 2 μm and 10 μm diameter particles in an integrated microfluidic chip.

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