A 12–18 GHz electrostatically tunable liquid metal RF MEMS resonator with quality factor of 1400–1840

In this paper we present a novel tunable RF MEMS resonator that is based upon electrostatic control over the morphology of a liquid metal droplet (LMD). We demonstrate a LMD evanescent-mode cavity resonator that simultaneously achieves wide analog tuning from 12 to 18 GHz with a measured quality factor of 1400-1840. A droplet of 250-μm diameter is utilized and the applied bias is limited to 100 V. This device operates on a principle called Electro-Wetting On Dielectric (EWOD). The liquid metal employed is a non-toxic eutectic alloy of Gallium, Indium and Tin known as Galinstan. This device also exploits interfacial surface energy and viscous body forces that dominate at nanoliter scale.