氣控式微粒慣性力聚焦分離微流體晶片

本研究利用慣性力聚焦之原理，配合氣控式側向薄膜之設計，改變流道幾何，進而影響內部流場以控制微粒之行為，最終完成一氣控式微粒聚焦分離微流體晶片。慣性力聚焦是操作在流場雷諾數1~100之區間，在此環境下微粒將受到剪切力梯度誘導升力與壁誘導升力之影響，兩方向相反之力彼此對抗使微粒產生側向位移，而當兩力達平衡時微粒則停止側向位移，微粒即呈現聚焦之狀態。慣性力聚焦為一被動式之聚焦分離方法，具有高通量、設計簡單等優勢。流道晶片之設計主要分為三個階段：第一階段聚焦流道、第二階段聚焦流道與微粒觀測區。第一階段聚焦流道以高深寬比之長方形截面設計，使微粒從原先入口處之散亂隨機狀態，匯聚在兩條聚焦線上；第二階段聚焦流道則在與第一階段流道相同的幾何下，增加設計一上一下、間隔0.5 mm的薄膜結構，單側薄膜數合計15個，且上下兩側之薄膜並不相連可獨立控制，另輔以凹槽結構來補足薄膜缺乏之形變量。當上側薄膜通入高壓氣體時，流場中將形成一副流影響上側聚焦點之穩定性，導致最終只留下下側聚焦點之微粒，反之則形成一反向之副流影響下側聚焦點之穩定性，留下上側聚焦點之微粒。微粒觀測區則為一漸擴流道，使流體流速減慢、顯微鏡視野擴大，便於後續拍攝分析。本研究之晶片在體積流速為300 μl/min (流場雷諾數約83)、單側薄膜通入空氣量為2.6 ml之環境下，直徑10 μm之微粒分離效率已可達75.6 %。此大小之微粒相當於血液中白血球之大小，將來具有應用於分離血液中血球及細菌之潛力。

關鍵字

慣性力；氣動平台；聚焦；分離；側向薄膜

並列摘要

In this work, we design a pneumatic-control microfluidic chip based on the theory of inertial focusing to create a single-stream particle flow at the downstream without sheath flow and external forces. The device consists of two stages of focusing channel and an observation zone. The first stage of focusing channel is a high aspect-ratio straight channel which could preliminarily align randomly dispersed particles to two focusing streams due to fluid inertia. The second stage of focusing channel is composed of a special symmetric notch-membrane structure inducing geometry-induced secondary flow to un-stabilize one of the two focusing stream. By inputting pressurized air to one side of lateral membranes, we could adjust the channel geometry in order to control the strength and the direction of secondary flow. Therefore, we can choose either of two focusing streams at the downstream. The observation zone is made up of a slightly divergent channel for decelerating the particles for the convenience of high-speed camera recording. In summary, we present a controllable single-stream device with separation efficiency (the total number of particles divides the difference of number of particles between two exits) as high as 75.6%. We also demonstrate the ability of separating 1 μm particles from 10 μm-1 μm mixture or 5 μm-1 μm mixture which has potential to application for blood separation.

並列關鍵字

inertial force ； separation ； focusing ； lateral membrane ； pneumatic control

參考文獻

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Chang, Y.-H., C.-J. Huang, and G.-B. Lee, "A tunable microfluidic-based filter modulated by pneumatic pressure for separation of blood cells," Microfluidics and Nanofluidics, 2012, 12(1): p. 85-94.

Choi, S., Sond, S., Choi, C., Park, J. K., "Hydrophoretic Sorting of Micrometer and Submicrometer Particles Using Anisotropic Microfluidic Obstacles," Analytical Chemistry, 2009, 81(1): p. 50-55.

國際替代計量

氣控式微粒慣性力聚焦分離微流體晶片

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