Abstract: A resonator device for measuring stress comprises at least two resonators, each resonator comprising an inter-digitated transducer structure arranged between two reflecting structures on or in a piezoelectric substrate, wherein the at least two resonators are arranged and positioned such that they have two different wave propagation directions, and each resonator comprises at least two parts with the area between the two parts of the at least two resonators forming a cavity, wherein the cavity is shared by the at least two resonators and wherein for at least one resonator, in particular, all resonators, the inter-digitated transducer structure comprises a first material and the reflecting structures a second material different from the first material and/or the inter-digitated transducer structure and the reflecting structures have different geometrical parameters. A differential sensing device comprises at least one resonator device as described herein.