High-velocity laser Doppler vibrometry measurements on an aluminum nitride bimorph wedge resonator

Recent advances in microelectromechanical systems (MEMS) have advanced inertial sensor technology. For resonant gyroscopes, sensitivity scales with the maximum velocity of the resonating mass, as higher velocities amplify the Coriolis force for faster and more accurate inertial signal detection-critical in navigation applications. Conventional MEMS remain in linear regimes, with velocities typically below 5 m/s. A recent Defense Advanced Research Projects Agency (DARPA) initiative challenges researchers to push resonator speeds toward material fracture limits, targeting up to 200 m/s and exploring regimes dominated by strong nonlinearities. This work investigates velocity limits in piezoelectrically driven mechanical resonators imposed by nonlinear dynamics and material constraints. We experimentally demonstrate an AlN bimorph wedge resonator reaching 50 m/s, achieving a ten-fold improvement over current limits. These results highlight the feasibility of operating MEMS devices at much higher velocities, paving the way for next-generation inertial sensors with increased performance. The resonator operates at a higher-order mode near 1.81 MHz, with clear evidence of Duffing-type nonlinearities at large drive amplitudes, as confirmed in time-domain and frequency-domain measurements.