A flexible supporting layer-based cross beam-cantilever type piezoelectric MEMS speaker with reliability

The rapid progression of micro electro mechanical systems (MEMS) technology has made it possible for piezoelectric MEMS speakers to replace traditional ones. However, the traditional thin film-type, piston-type and cantilever-type piezoelectric MEMS speakers with Si supporting layer still suffer from the key problem of small sound pressure level (SPL) and reliability. In this paper, a flexible supporting layer-based cross beam-cantilever type piezoelectric MEMS speaker with reliability is proposed, which four trapezoidal cantilevers symmetrically distributed along the cross beam within a square with a side length of 4 mm, realizing a comparable SPL compared with the aforementioned traditional three types of piezoelectric MEMS ones based on Si supporting layer, and achieving good reliability. The measurement results in acoustics test adaptor show that under a driving voltage of 1 Vrms, within the range of human hearing spans from 20 Hz to 20 kHz, the SPL exceeds 50.3 dB, meeting the basic requirements for human hearing. The multiple tests also exhibit relatively consistent SPL curves, and the total harmonic distortion is less than 3.8% when the frequency is greater than 430 Hz. Furthermore, the experiments also reveal that the device does not exhibit any significant change in SPL when dropped from a height of 3 m or when playing music continuously for 3 h, further demonstrating its reliability. The designed cross beam-cantilever piezoelectric MEMS speaker offers fresh perspectives for researchers and enterprises, with the potential to speed up their development and practical implementation.