Electroacoustic parameter extraction of a piezoelectric microelectromechanical systems microphone Free

A novel suite of parameter extraction experiments were used to assess the accuracy of individual elements of a lumped element model for a microelectromechanical systems based piezoelectric microphone. The MEMS microphone was developed via model-based design utilizing the lumped element model for use in aeroacoustic applications. Laser vibrometer scans of the microphone diaphragm while subjected to electrical or pressure excitation provided experimental predictions for the effective electroacoustic piezoelectric coupling coefficient, diaphragm compliance, and mass. The experimental results were compared with analytical predictions from a piezocomposite diaphragm model for these individual lumped elements. Associated lumped element model predictions were also compared with the results of device characterization experiments. Similar trends in theory and experiments were observed, though comparative error in element values was attributed to uncertainty in model-inputs, most notably thin-film residual stresses in the microphone diaphragm. [This work was sponsored by Boeing Corporation.]