Abstract
Digital microfluidics has the incomparable advantages over the traditional ones, making the research of manipulating, mixing and separating of droplets a major topic. The mixing efficiency, implemented by the effect of EWOD, can be highly improved by actuation of droplets under its resonance frequency which creating the maximal amplitude and internal flow vortex while oscillation. The results show that two-plate EWOD, limited by the space, has larger resonant frequency with comparison of single planar EWOD. Also this article demonstrated that the narrower the gap between the electrodes is, the wider the droplet’s contact areas are. The result complies with the literature. Conclusion is that droplet of 7 μl volume has better mixing efficiency when actuated under the resonant frequency. Among the resonant frequencies, 165 Hz attains the best result, with the time for only about 6.7% of mixing by natural diffusion. In addition, we found that, by alternating periodically two driving frequencies, can the mixing efficiency be achieved to a greater extent.