微渦漩混和器之研究

Abstract

這項混和器的研究利用到一個由三維對轉旋轉流場作為高速混和的混和機制。其特色在於表面鍍金膜的懸浮震盪結構所造成的穩態流場。此震盪結構中央為一200μm × 100μm的微平板，兩端以500μm長的懸樑支撐之。為結構通以交流電壓，微結構下方的外加磁場可使其在平面上因著勞倫茲力的作用下震盪。兩相異流體，以背景流速36.4mm/s(Pe= 6.61×104, Re= 1.72)流經震盪微元件，在三維旋轉流場的作用下可以在900μm的長度內增加72%的混和效率。而相同的長度900μm之下，背景流速10mm/s，5mm/s則分別可以提昇71%以及56%的混和效率。此三流速之下的混和效提昇率顯示雷諾數與混和效率的不相關，在高雷諾數(Re≧1)下仍能有70%的混和效率提升。此實驗的應用則為分別通入紅血球以及紅血球裂解液至微元件中，紅血球裂解率的提昇則作為此元件混和效率的參酌。結果顯示在一公分的距離內，元件可提供68%的裂解率；而在長直流到內，紅血球及其裂解液藉由擴散只能達到1.7%的裂解率。結果亦顯示了藉由控制共震平板導通電壓可提供不同的裂解率。此特性可利用於血球的純化，提供目標血球免於受到因人為的操作產生變異或過量壓迫的裂解環境。

This work presents an ultra-fast micromixer via a pair of 3D, counter-rotating, circulatory flow structure. This feature is secondary steady streaming induced by a resonating gold-coated suspended structure, consisting of two long beams (400um length) supporting a microplate (100um × 200um) at the center. As AC current passes through this structure, an external magnet placed underneath forcing the microplate to in-plane resonance as result of Lorentz law. Two heterogeneous streams passes the 3D circulatory flow results in a mixing efficiency increase of 72% within 900μm mixing length, under background flow speed of 36.4mm/s, Pèclet number of 6.61×104, Reynold’s number of 1.72. For background flow speed of 10mm/s and 5mm/s, 71% and 56% of increase mixing efficiency under same mixing length of 900μm, implies a mixing efficiency independent of Reynold’s number. Application of the device to enhance lysis of erythrocytes is made by in-flowing of the cells in one stream and lysis solution in another. Results showed a 68% lysis rate could be obtained within 1cm mixing length, where as only 0.7% for a straight channel. Furthermore, lysis rate could be controlled by excited AC voltage on the oscillating plate according to results obtained, which could provide an environment for erythrocyte lysis and prevent stress target cells for extended period in macroscale isolation, which could avoid differentiations caused by manual manipulation.