Excitation of Vibrational Eigenstates of Coupled Microcantilevers Using Ultrasound Radiation Force

A coupled pair of 500 μm length microcantilevers was excited using the ultrasound radiation force. The excitation was produced using the difference frequency between the two sidebands of a double-sideband suppressed carrier AM (DSB-SC-AM) waveform centered on 500 kHz that was emitted by a focused ultrasound transducer. A laser Doppler vibrometer measured the frequency response and deflection shapes of the cantilever pair. The measured frequencies of the symmetric and antisymmetric eigenstates of the first transverse mode at 10 kHz excited using the ultrasound radiation force were consistent with frequencies measured using a scanning-probe microscopy system. The ultrasound radiation force was also used to excite the symmetric and antisymmetric eigenstates of the 60 kHz second transverse and 86 kHz first torsional modes. These results demonstrate the capability of using the ultrasound radiation force for excitation of structures in air that are significantly smaller, and with higher resonance frequencies, than in any previous study.