以電極化力操控介電流體於數位流體平台之研究

Abstract

以液滴為主體的微流體 (如數位微流體)，對於光學、電學和實驗室晶片的應用潛力上受到很大的矚目。不同的液滴在平行板中的驅動機制也被研究探討著，其中以電的方法，如介電泳及介電濕潤來驅動和設計晶片為主要。然而這些的驅動機制都是建立在導電的水溶液上，如人的生理流體；而非水溶液的液滴雖然也可以被介電濕潤所驅動，但不導電 (介電) 的液滴卻無法成功地被驅動。所以，若能驅動導電及介電液滴，數位化的實驗室晶片或微全分析系統將具更完備的的功能。在本論文中，我們成功地在間距為150 □m的平行板晶片上以電極化力操控介電流體，如矽油、癸烷、正十六烷等液滴，使得數位微流體系統，從原本僅能操控導電流體延伸到介電流體。我們並在實驗中以不同黏滯度的矽油，20、50 cSt， 在不同間距的平行板中利用電極化力來運輸、切割及合併油滴，並對初始及切割的電壓作測量和比較。針對黏滯度與驅動電壓的關係在本論文裡也做相關的研究及探討。

Droplet-based microfluidics, i.e., digital microfluidics, has drawn much attention for its potential applications in optics, electrics, and lab-on-a-chip. Several droplet driving mechanisms have been investigated in a parallel plate device. Among them, electrical means are intensively researched for their simple actuation and device design, such as dielectrophoresis (DEP) and electrowetting-on-dielectric (EWOD). However, in most DEP and EWOD droplet manipulations, conductive and aqueous solutions were usually examined, including human physiological fluids. Although non-aqueous solvents and solutions were previously actuated by EWOD, dielectric droplets have not been successfully pumped. To realize a digital□□-TAS, driving both conductive and dielectric droplets is mandatory. In this thesis, Dielectric droplets are successfully manipulated by electropolarization forces in a parallel plate device, which extends the liquid handling capability of digital microfluidics from merely conductive droplets to dielectric ones. Actuations of silicone oil, decane, and hexadecane droplets in a 150-μm-high gap between parallel plates are demonstrated. Silicone oil droplets of different viscosities, 20 and 50 cSt, are transported and split in various gaps heights, demonstrating the manipulation capabilities of electropolarization forces. The threshold and splitting voltages are measured and compared. Moreover, the relationship between the velocity and driving voltage is studied.