Analysis of the quality factor of AlN-actuated micro-resonators in air and liquid

The quality factor (Q) of different modes of self-actuated aluminium nitride beams operated in air and liquid media is analyzed applying different techniques. In air, both optical and electrical techniques are used. In the case of the optical approach, characterization is done with a laser Doppler vibrometer. The values for the Q factors are deduced straight forward from both the frequency spectrum and the transient response, while electrical impedance measurements need a more careful evaluation with two different fitting methods to obtain the Q factor of the vibration modes. In water, only optical measurements, more sensitive than the electrical measurements, could be used to determine the Q factor of selected modes. In addition, the results of finite element model analysis were compared to the experimental data, showing an excellent agreement regarding the modal shape and the resonance frequency of the microresonators.