- 學位論文
以非穩態流場開發多功能微流體裝置之研究
Development of Multifunctional Unsteady Flow Microfluidic Device
摘要
摘要 本研究之目的為以非穩態流之流場特性開發一多功能微流體裝置，以作為未來實驗室晶片或是微型全分析系統之流體前置處理之應用，本裝置可以完成實驗室晶片或微型全分析系統在分析前之流體混合與微粒子分離的需求，本研究主要是利用非對稱擋體結構配合PZT壓電片的震動，可在裝置內產生一非穩態流場，此流場是本裝置擁有高混合效率與粒子分離效能的基礎。透過壓電片驅動電壓與工作頻率的改變，可以控制流體的流動方向。在工作頻率為1.0kHz時，可以分別在注入區與三叉型區域得到95%以上混合效率與接近100%的微粒子分離效率。 本裝置的體積為 ，而且只需一道光罩與一次電感耦合電漿蝕刻製程，就可以完成整個微流體裝置的製作，相較於前人開發的繁複製程，不僅簡化以提高良率，更大幅縮小元件的體積。本裝置於微流道中央配置一非對稱擋體，並於流道二側分別設置三個交錯排列的凸塊，再配合壓電片所產生的非穩態流場，而得到一高效能的微混合機制，此外，在另一裝置中，設置了三個注入流道的輸入口，使得流道在流經非對稱擋體前就可以預先進行混合，此設計的優點是二種待混合流體可以同時流經流道中的最窄處，充分發揮非對稱擋體後方流場迴流區的功能，達到良好的混合效果，有效縮短混合所需的長度與時間。 在非穩態流場狀況下，流體流經三叉型區域會有三個現象促使微粒子往二側輸出流道移動，首先流體在主流道流動時，微粒子會往流道二側靠近。其次，當流體移動至三叉型區域時，會因截面積擴大而降低流速，並在二側產生迴流區，此迴流區會將微粒子往三叉型區域二側帶動，最後在中央流道入口端會產生一對稱之渦漩流場，此渦漩可作為一阻擋微粒子前進之擋體，造成中央輸出流道的截面積縮減與流阻提昇，且由於渦漩的旋轉方向是由中央流道往二側輸出流道旋轉，因此可帶動微粒子往側邊輸出流道前進，在上述三種現象的配合下，可以有效達到分離微粒子的效果。 此外，本研究應用微粒子顯像測速儀配合同步觸發裝置，以全域照亮法將欲觀測之微流道全域照亮，以完整了解注入區之非穩態流場的速度結構與流場特性，並對觀測結果加以分析歸納。本研究預期整合上述的研究成果進行一系統開發，配合理論分析並結合相關影像處理技術將實驗結果量化，以對此一多功能微流體裝置的研究開發獲得完整成果，並建立起一套微流體系統開發的流程。
並列摘要
Abstract In this study, the results of two unsteady flow microfluidic devices with multifunctions of fluid pumping, mixing and particle removal are presented. This present device was developed by utilizing the microchannel unsteady flow phenomenon, which was due to the oscillation of a PZT membrane. The flow direction can be controlled by the amplitude and the frequency of the driving power on the vibrating membrane. At a driving frequency of 1.0 kHz, the optimum mixing (over 95%) and particle removal efficiency (close to 100%) are observed at the inlet region and the trifurcate zone. The fabrication process of this device was simple since only one photo mask, one ICP etching step and anodic glass bonding were required. As for the design of valveless micropump, one asymmetric obstacle was used for the flow-directing device instead of the diffuser/nozzle elements used in previous studies. A mixing region with triangular-wave structures and a trifurcate zone with triple outlet channels were integrated with an obstacle-type valveless micropump for the present multifunctional device. Two side inlet channels with an incline angle of 40° were placed on both sides of the center inlet channel. The fluids from the center and the side inlet channels flow through the throat between the obstacle and the side-wall. Two recirculation zones occurred upstream the obstacle to enhance the mixing efficiency. Downstream the oscillating chamber, the main channel was connected to a trifurcate zone. The flow velocity in the main channel was measured by flow visualization. At the trifurcate zone, two recirculation zones and two vortices were induced on the both sides of the trifurcate zone and upstream the inlet of the center outlet channel due to the unsteady flow. These vortices served as obstacles to increase the flow resistance of the center channel. Based on the rotating direction of these recirculation zones and vortices, the particles were driven towards side outlet channels to achieve the removal effect. Micro-particle-image-velocimetry (μ-PIV) with external trigger was used to measure the flow characteristics of the inlet region. Streamtrace patterns were obtained at the inlet region in a time period. Image processing was used to count the number of particles and to analyze the removal efficiency. This study indicates that this device fulfills the demands for sample preparing of bio-chemical or bio-medical systems. Moreover, the present device can be applied to μ-or lab-on-achip with integration of biosensors in the future.