Design of crescent driving electrodes for digital electrowetting-on-dielectric devices

To reduce the driving voltage of the digital microfluidic device, the traditional square electrode structure was designed to crescent shapes, and the driving effects of crescent shape electrode structures with different parameters were investigated. First, the effect of different electrode shapes on reducing the driving voltage was analyzed based upon the theory of electrowetting-on-dielectric. Then, the moving process was numerically simulated by means of Volume of Fluid (VOF). Based upon simulation results, the moving process of the same droplet in different electrode structures was analyzed. Finally, four electrodes with different crescent shapes was designed and their driving effects for the same droplet were verified. The experimental results show that the crescent electrode device with the arc diameter equal to the length of the electrode is able to reduce the driving voltage by 15.6% more than those of other three crescent shape electrode devices. Besides, the 1 μL droplet on this electrode structure device can be driven successfully with the velocity of 1.6 cm/s when the driving voltage is just 16 V, accordingly, which shows that this configuration design is the optimal structure among various crescent electrode structures. In conclusion, the obtained experimental results validate the feasibility that the crescent electrode with the arc diameter equal to electrode length can reduce the driving voltage effectively.