Motion Characteristics of Orbital Electrowetting-on-Dielectric Droplets on Superhydrophobic Surfaces

Compared with traditional electrowetting-on-dielectric (EWOD), orbital EWOD is a newly observed droplet manipulation phenomenon on a superhydrophobic surface, which has the advantages of high speed, antigravity, and no pollution and has broad application prospects. However, the current research on electrowetting and structured electrodes focuses on the statistical characteristics of droplet collection, and the movement process of single droplets is still unclear. The study of eccentric droplet correction helps us to better understand the influence of local energy on droplets and provide ideas for designing hybrid circuits that can realize more functions. Based on the existing EW driving force models and experiments on superhydrophobic surfaces, the EW force correction factor is introduced, and the phase-field simulation software COMSOL Multiphysics is used to simulate the motion process of 10 μL droplets in 250 V (1000 Hz) with a straight orbit, inclined orbit, circular arc orbit, and eccentricity of coplanar electrodes. The motion characteristics and traveling modes of the droplets are summarized. In a straight orbit, the spreading radius of droplets is about 1.09 times the initial radius, the maximum inclination angle of droplets is 9.8°, and the maximum correction force is about 24.7 μN at an offset of 297 μm.