A Center-Bound Type Piezoelectric MEMS Speaker With Flexible Supporting Layer

Conventionally designed edge-bound type piezoelectric Micro Electro Mechanical Systems (MEMS) speakers with Si supporting layer still suffer from the problem of low sound pressure level (SPL) and high total harmonic distortion (THD). In this paper, we demonstrate a center-bound type piezoelectric MEMS speaker based on flexible supporting layer, which meets the minimum SPL requirement for human hearing, and achieves a lower THD over a wider continuous frequency band compared with the reported state-of-the-art works, and demonstrates good reliability and durability. Test results in an acoustics test adaptor show that at a driving voltage of 1 V${}_{\mathbf {rms}}$, greater than 52dB SPLs are obtained in the human audible range of 20Hz-20kHz, basically meeting the minimum auditory requirements for human beings. The applicable working frequency range for THD of this device spans the medium and high frequency band of 500 Hz-20 kHz. Compared with state-of-the-art reported works, it achieves a THD of$\le 5$% over a significantly wider continuous frequency range. Moreover, this speaker produces no abnormal sound, shows no fracture after dropping from a height of 5meters, and maintain at least 90% of the SPLs after playing music continuously for 100 hours. The proposed center-bound type piezoelectric MEMS speaker with flexible supporting layer is expected to drive its own development and practical application by offering new perspectives and design concepts to researchers and enterprises. [2025-0116]