Fabrication and characterization of liquid metal-based micro-electromechanical DC-contact switch for RF applications

E. Cagatay, Y. Damgaci, B.A. Cetiner, N. Biyikli
Bilkent University - UNAM, TR

Keywords: micro-electromechanical, liquid metal, micro-fabrication, electro-wetting, droplet actuation, RF-switch, DC-contact switch


Electrowetting-on-dielectric (EWOD) is the phenomenon in which the wetting properties of a liquid are modified by the influence of an applied electric field. By EWOD, a conducting or non-conducting liquid can be moved using a device consisting of a dielectric layer on top of a metal electrode to which the electrostatic actuation voltage is applied. Our aim in this study is to characterize and examine the actuation of metallic liquid droplets, namely Eutectic Gallium Indium (EGaIn) and Gallium Indium Tin alloy (Galinstan), using EWOD for potential RF-swithcing applications. The devices were fabricated using a 5-level microwave-compatible microfabrication process. Characterization of the test devices involved visual inspection with optical microscope and SEM, I-V measurement with parameter analyzer and contact angle measurements of DI-water on hydrophobic surfaces. With the application of 120-140V voltage difference across the actuation electrode and the ground electrode, the metallic liquid droplets were observed to be actuated. Actuation experiments in closed-pack microfluidic channels were also successful with slightly higher actuation voltages. The effect of dielectric layer material and thickness on the actuation voltage was studied as well.