Digital microfluidics technology based on the electrowetting-on-dielectric effect is a popular emerging technology whose objects of control are individual droplets on the microliter or even nano-liter scales. It has unique advantages such as rapid response, low reagent consumption, and high integration, so it has drawn widespread attention and use in the biological, medical, and chemical fields. However, to date, there has been relatively little research conducted on the mechanism of droplets transition from stillness to motion by electrowetting-on-dielectric actuation. Here, we studied the polarization mechanism underlying solid–liquid contact surface, thus building upon the previous research. The electric field in chip, internal pressure, and flow field of droplet were modeled and simulated numerically. Then, the process and mechanism of droplet transition from stillness to motion was comprehensively analyzed, and the results obtained from the simulation and discussion were in close agreement with experimental results. It is here shown that the process of droplet from stillness to motion involves four successive steps, which helps to better understand electrowetting-on-dielectric-induced droplet motions and physics of digital microfluidics systems. The aim of this work was to research basic physical mechanisms of electrowetting-on-dielectric droplet motion on a common ground so that the researchers may form a clear picture of the fundamentals.
Digital microfluidics Electrowetting-on-dielectric Droplet motion Hydrostatic pressure Driving mechanism
47.55.D− 68.03.Hj 68.03.Cd 77.22.Ej
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This work was supported in part by the Zhejiang Provincial Natural Science Foundation of China (Grant No. LQ16E050008), the Key Laboratory of Air-driven Equipment Technology of Zhejiang Province (Grant No. 2018E10011), and the National Natural Science Foundation of China (Grant No. 51275327).