School of Engineering, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC, CanadaV1V 1V7.
Lab Chip. 2010 Jun 7;10(11):1429-35. doi: 10.1039/b925665b. Epub 2010 Mar 10.
Real-time characterization of digital microfluidic lab-on-a-chip devices is important for biological and chemical applications in which the properties of the microdroplet are time variant. In this paper, a method for in situ characterization of microdroplet interfacial properties is introduced. The proposed characterization method relies on two submodules, namely the contact angle and capacitance sampling submodules, in a digital microfluidic system. In the contact angle measurement submodule, the microdroplet profile is acquired and an accurate contact angle is determined. In the capacitance sampling submodule, the capacitance of the system is measured by means of an activation voltage signal. For verification purposes, the results obtained from the proposed method are compared to the Lippmann-Young equation. The results are in excellent agreement with previously reported values. Finally, the proposed submodules are used to characterize the interfacial properties of a microdroplet containing an aqueous solution of bovine serum albumin (BSA) in which adsorption is a predominant effect. The results show the temporal behaviour of both microdroplet interfacial properties and dielectric characteristics.
实时表征数字微流控芯片设备对于生物和化学应用非常重要，因为在这些应用中微滴的性质随时间变化。本文提出了一种用于微滴界面特性原位表征的方法。该方法依赖于数字微流控系统中的两个子模块，即接触角和电容采样子模块。在接触角测量子模块中，获取微滴轮廓并确定准确的接触角。在电容采样子模块中，通过激活电压信号测量系统的电容。为了验证目的，将所提出方法的结果与 Lippmann-Young 方程进行了比较。结果与之前报道的值非常吻合。最后，使用所提出的子模块来表征含有牛血清白蛋白（BSA）水溶液的微滴的界面特性，其中吸附是主要作用。结果显示了微滴界面特性和介电特性的时间行为。
