High-Performance Piezoelectric MEMS Speakers for in-ear Applications

This work presents a series of high performance piezoelectric Micro Electro Mechanical System (MEMS) loudspeakers for in-ear applications. They consist of piezoelectrically actuated thin plates implementing narrow gaps, and an optimized geometry configuration to improve the system linearity and power consumption. The devices feature a Sound Pressure Level (SPL) up to 109 dB SPL from 100 Hz onward for an actuation of 30 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\mathrm{p}\mathrm{p}}$</tex>, a Total Harmonic Distortion (THD) lower than 1 % at 1 kHz and at 94 dB SPL and a compact footprint of 4, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5\mathrm{x}4.5\text{mm}^{2}$</tex>.