Sensitivity improvement of split-ring resonators for thin-film sensing using floating electrodes

An implementation of split-ring resonators for thin-film sensing is proposed. By creating a cavity with a floating electrode and under-etching of the gap of the split-ring resonator, the electric field lines are concentrated in the material under test. Simulations of the proposed structure yield a relative frequency shift of 19 % for a variation of the relative permittivity between 1 and 5 at an operation frequency of 303 GHz.