石英共振微天平應用於接觸角分析及微液滴生物感測器

Abstract

在微觀世界中，表面張力比重力影響更大，因此獲得表面張力的資訊在微流體系統研究中是很重要的課題。然而，要直接量測表面能是一件困難的事情，一般是藉由接觸角的量測計算反推而得。光學分析系統是傳統獲得接觸角的方法，但其具有光學性質的限制諸如：折射、反射、繞射和散射。尤其當系統中含有兩相液體時 (如水在油中) ，此問題更趨嚴重。因此，發展一不需光學做為媒介的接觸角量測系統乃至關緊要之事。 自1950年迄今，石英共振微天平 (QCM) 已成為一常見之質量量測技術，被廣泛應用在沉積系統控制、薄膜研究以及分析化學上。在稍後的研究中，石英共振微天平更被發現可以有效的量測液體黏滯度、密度甚至是表面接觸角。在本論文研究中，利用石英共振微天平進行介電濕潤中接觸角之量測，建立起單一相及兩相液體之模型並驗證於實驗。另一方面，初步地測試了數位微流體系統與石英共振微天平之結合，在石英共振微天平上驅動微升等級的液滴，並且利用螢光觀察和接觸角分析，確定了Strepavidin固定化機制，以利後續研究。

In the microscopic world, surface tension is more powerful than the gravity; hence it is an important issue to get the information of surface energy in the research of microfluidic system. However, it is hard to measure the surface energy directly but easy to calculate it from the contact angle. Optical analysis system is a conventional method to measure the contact angle, but it is confined by the optical property such as refraction, reflection, diffraction, and scattering. This issue occurs while the system includes two liquid phases (e.g., water in oil). As a result of it, developing a method to measure the contact angle without optical method is important. Quartz crystal microbalance (QCM) is a well known and promising technology of mass-sensor such as deposition process control, thin film study, and analytical chemistry since 1950. In the later publication, QCM is also found to be an effective method of studying the property of fluidics such as viscosity, density, and the contact angle on the surface. In this research, QCM was employed for the contact angle measurement in EWOD phenomena, the models of one and two liquid phases were built and proved. In the other hand, the combination of digital microfluidic system and QCM were tested preliminarily. Micro scale droplet manipulation was demonstrated on QCM and the strepavidin immobilization was also confirmed by contact angle measurement and fluorescence.