Dielectrically stabilized electrowetting on AF1600/Si3N4/TiO2 dielectric composite film

In this paper, we propose a dielectrically stabilized and reversible electrowetting-on-dielectric (EWOD) platform based on a multi-layered insulator composed of amorphous fluoropolymer (AF1600), silicon nitride (Si3N4), and titanium dioxide (TiO2). Although TiO2 can reduce the electrowetting voltage owing to its high relative permittivity, κ, an EWOD platform composed of only TiO2 is vulnerable to current leakage. The proposed AF1600/Si3N4/TiO2 (20 nm/20 nm/20 nm) EWOD platform exhibited enhanced dielectric strength as well as a low contact angle hysteresis within 2° of the droplet. Because a Si3N4 film has excellent dielectric strength as compared to AF1600 and TiO2 films, it can safeguard the EWOD platform from both current leakage and dielectric breakdown. The electrowetting capability of the AF1600/Si3N4/TiO2 EWOD platform was improved by means of a thin fluoropolymer film with a thickness of less than 20 nm.