Dual-Frequency Aluminum Scandium Nitride Piezoelectric Microphones with Wide Bandwidth, Large Dynamic Range, and High Sensitivity for Wind Tunnel Testing

A dual-frequency piezoelectric micro-electro-mechanical system (MEMS) microphone based on highly doped aluminum scandium nitride (AlSc30%N) thin films have been developed for wind tunnel testing with strict requirements of wide bandwidth, large dynamic range, and high sensitivity. Compared to the MEMS sample based on lead zirconate titanate (PZT), the new AlSc30%N MEMS sample has much higher sensitivity and requires no DC bias. The preliminary aeroacoustic tests, conducted on the BACCHUS test bench of Airbus, show that the sensitivity and signal-to-noise ratio (SNR) is 3.2 mV/Pa and 60.2 dB, and the upper limits of frequency range and dynamic range >55 kHz and >147 dB SPL. The overall performance is better than the state of art microphones for aeroacoustic measurements.