Modeling on electrowetting-on-dielectric (EWOD)

Electrowetting induced droplet, bubble dynamics as well as oscillation of interfacial wave have been studied numerically in this paper. The level set method has been used to track the interface of water and air. The capillary wave on the droplet and bubble interface could be seen during the electrowetting effect. The sudden variation of the bubble and droplet base creates a disturbance that propagates along the surface in the form of a capillary wave. As the wetted area is reduced during this transformation, the excess surface energy is converted into kinetic energy which stretches the droplet vertically and eventually leads to the detachment from the substrate; the results have been validated with available experimental data. The boundary between two immiscible fluids is susceptible to waves when disturbed with contact angle changes, as a result of exchange between the kinetic energy of the fluids and the potential energy either due to gravity or surface tension. This gives rise to the use of electrowetting to generate surface waves. The frequency relationship between voltage signal, contact angle and surface wave has been examined. The mechanism of the electrowetting induced surface wave have been explored to detach the bubbles.