# A Fixed-End Beam–Cantilever Piezoelectric MEMS Speaker with Flexible Supporting Layer

## TL;DR

This paper introduces a new piezoelectric MEMS speaker design with a flexible support layer that achieves high sound quality and reliability.

## Contribution

A novel fixed-end beam–cantilever MEMS speaker with a flexible supporting layer is proposed, offering improved reliability and sound performance.

## Key findings

- The speaker achieves over 51.6 dB SPL at 1 Vrms in the audible frequency range.
- THD remains below 3.4% above 430 Hz, meeting human auditory requirements.
- The design shows no fractures after drops and retains 92% SPL after 100 h of playback.

## Abstract

Conventionally designed piezoelectric micro-electro-mechanical systems (MEMS) speakers with thin-film-type, piston-type, and cantilever-type vibration membranes still adopt a Si supporting layer, which not only hinders the improvement of sound pressure level (SPL) but also lacks characterization of reliability. In this paper, we propose a fixed-end beam–cantilever piezoelectric MEMS speaker with a flexible supporting layer, achieving an SPL comparable to that of traditional three types of piezoelectric MEMS speakers with a Si supporting layer, and displaying good reliability. The measured results performed on encapsulated prototypes mounted to an acoustic test adaptor demonstrate that under a driving voltage of 1 Vrms, the SPL exceeds 51.6 dB in the human audible frequency range of 20 Hz–20 kHz, the total harmonic distortion (THD) remains below 3.4% above 430 Hz, satisfying the basic requirements for human auditory perception. Moreover, further experiments also prove its reliability by revealing no abnormal sound output, no fracture after being dropped from heights of 1 to 5 m, and the retention of over 92% SPL following 100 h of continuous music playback. This fixed-end beam–cantilever piezoelectric MEMS speakers with a flexible supporting layer provide researchers and enterprises with brand-new design ideas and a fresh perspective, which may potentially promote their development and practical application.