Push–pull actuated MEMS piezoelectric speaker for enhanced sound pressure level

MEMS loudspeakers combine high miniaturization, low power consumption, and seamless integration with on-chip electronics, making them attractive for modern consumer devices. However, their acoustic output still lags behind that of conventional drivers, requiring further optimization. In this work, we present a novel piezoelectric MEMS loudspeaker designed for in-ear applications, featuring a tailored actuation scheme that enhances sound pressure while maintaining a compact footprint. The proposed device employs a piezoelectric diaphragm patterned with 5 µm slits to reduce stiffness while preventing acoustic short-circuiting, and two distinct piezoelectric patches driven with 180 out-of-phase sinusoidal signals to maximize displacement. The proposed device achieves a Sound Pressure Level (SPL) exceeding 109.5 dB from 100 Hz onward under a 30 Vpp excitation, within a 4.5 4.5 mm 2 footprint. Compared with a single-patch piezoelectric speaker of equal capacitance and footprint, the proposed device demonstrates SPL improvements of 1 dB at 100 Hz and 2 dB at 1 kHz, in close agreement with predictions from a full-order Finite Element Model (FEM).