Design of Crescent Splitting Electrodes in EWOD Device

High control voltage and low success rate limit the application of droplet cutting on digital microfluidic chip, hence, the traditional square electrode was designed to crescent electrode to solve these problems in this paper. First, the relationship between the EWOD tension of micro-droplet and the chord length of effective Triple Contact Line (TCL) was analyzed based on the theory of electrowetting-on-dielectric. Then, the droplet cutting processes of different electrodes were numerically simulated and the results were analyzed. Finally, the effect of droplet cutting on four kinds of chips were tested. The results revel that the crescent electrode can decrease the applied voltage for droplet cutting and the minimum voltage required for cutting on crescent electrode (A=1.41) was at least 13.9% lower than that of square electrode. In addition, the success rates of droplet cutting on crescent electrode at different channel heights are higher than that of square electrode.