Dielectrically stabilized electrowetting on AF1600/Si 3N 4/TiO 2 dielectric composite film

Abstract

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 (Si 3N 4), and titanium dioxide (TiO 2). Although TiO 2 can reduce the electrowetting voltage owing to its high relative permittivity, κ, an EWOD platform composed of only TiO 2 is vulnerable to current leakage. The proposed AF1600/Si 3N 4/TiO 2 (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 Si 3N 4 film has excellent dielectric strength as compared to AF1600 and TiO 2 films, it can safeguard the EWOD platform from both current leakage and dielectric breakdown. The electrowetting capability of the AF1600/Si 3N 4/TiO 2 EWOD platform was improved by means of a thin fluoropolymer film with a thickness of less than 20 nm.