Fig. 1: Piezoelectric resonance sensors operating at Fano-like resonances.

a The equivalent circuit representation of the piezoelectric resonator, and an external shunt capacitor is connected to the resonator. b Schematic diagram and partial SEM image of the fabricated SAW resonator for humidity sensing. c The measured admittance (Y11) as a function of frequency for different shunt capacitances. d The measured scattering parameter (S11) as a function of frequency for different shunt capacitances. Cp = 0 in (c, d) corresponds to the as-fabricated resonator