Lithium niobate microphone with high SNR potential

We present a lithium niobate (LN) microphone prototype, the first to explore LN as a transducer material for high signal-to-noise ratio (SNR) applications. The design utilizes a bimorph configuration with opposing polarizations, fabricated through a wafer bonding process. The prototype features a 300-μm thick LN diaphragm, which enables lateral electric field sensing from acoustic pressure-induced deformation. Laser Doppler vibrometry and pitch-catch acoustic tests validate diaphragm performance, supported by finite element and lumped element modeling. While initial measurements demonstrate proof-of-concept only, modeling predicts a potential SNR higher than 70 dB for microphones in a 3.76 mm × 2.95 mm × 1.1 mm package. Future work will focus on realizing such a microphone. This, in-turn, requires thinning the LN diaphragm to 2 μm to enhance sensitivity, while optimizing electrode design to maximize performance.