Multimode characteristics of high-frequency CMOS-MEMS resonators

Multimode resonators offer new opportunities for resonant sensing with multimodality and enhanced degrees of freedom. This digest paper presents experimental measurements of multimode resonances in `dog-bone´-shaped resonators made by Si CMOS-MEMS processes. We have measured >18 modes which include both out-of-plane and in-plane resonances. We compare multimode results from both photo-thermal and capacitive actuations. We show that photo-thermal scheme can simultaneously excite many more modes, while capacitive actuation is more selective in modes and only efficiently couple to certain in-plane modes. The discovery of the many modes in these CMOS-MEMS resonators opens new possibilities for exploiting such devices for multimode resonant sensing, and for exploring coupling effects and spurious mode suppression techniques.