Authors: A. Ahmadi, K.D. Devlin, H. Najjaran, J.F. Holzman, M. Hoorfar
Affilation: University of British Columbia, Canada
Pages: 452 - 455
Keywords: digital microfluidic, electrowetting, biomolecular adsorption
Digital microfluidic lab-on-a-chip technology has been a new trend in miniaturizing biomedical platforms. However, nonspecific adsorption of these biomolecules has proven to be one the greatest sources of uncertainties for these biofluidic chips. Unwanted adsorption ultimately decreases the device sensitivity and severely limits the device performance. An accurate understanding of the adsorption process on these biochips is needed to allow for successful device design and its implementation. In this paper, the protein adsorption process in electrowetting-based digital microfluidic devices is investigated and modeled. An analytical method is used to develop a new formulation for the relationship between the time-varying contact angle and applied voltage. It is found that the contact angle is a strong function of the protein bulk concentration as well as the protein molecular characteristics. The model describes the kinetics of the diffusion-controlled interfacial changes as well as the conformational changes of the adsorbed molecules. The accuracy of the model is verified by a direct comparison of these findings with experimental data. The comparison of the experimental and modeling results shows that the presented model is able to describe accurately the underlying physics of the biomolecular adsorption process, and insight is gained into the complexities of protein-based biochips.