We propose a method to evaluate the Total Harmonic Distortion generated by a cantilever-based PZT loudspeaker inside an IEC 60318-4 coupler. The model is validated using experimental data of a commercial loudspeaker. Using the time domain equations of the equivalent electrical circuit of the loudspeaker inside the coupler and a state space formulation, the acoustic pressure response is calculated and compared to the measurement of the manufacturer. Next, the stiffness, transduction and capacitance nonlinear functions are evaluated with a Double-Beam Laser Interferometer (DBLI) and a nanoindenter on test devices and on the commercial loudspeaker. By introducing the nonlinear functions into the model as amplitude-dependent parameters, the THD generated by the loudspeaker is calculated and compared to the value provided by the manufacturer. The good agreement between the measurement and the simulation could allow for a rather quick simulation of the performance of similarly designed loudspeakers at the early stage of the design, by only estimating the static linearity of the main nonlinearity sources.

At the era of powerful computers, it is tempting to employ finite element models early in the design phase of a device. However, especially for MEMS devices, the dimensional ratios and short wavelengths compared to the device’s dimensions, along with the involvement of multiple physics, can necessitate complex and computationally intensive models, making them impractical for optimization processes. Hence, reduced order models, like the lumped element model, are often preferred as they accurately represent complex system behaviour within a defined frequency range. This review explores the use of lumped element models and their corresponding electrical equivalent circuits for simulating MEMS electro-acoustic devices, offering insights into their diverse applications within this specific domain.

Miniaturized loudspeakers are increasingly relevant for wearable and transparent electronics, but achieving consistent acoustic performance, particularly at low frequencies, remains a challenge. Here we show a polymer-based loudspeaker that features a partially stiffened membrane actuated by a transferred thin film of lead zirconate titanate. The flexible polymer reduces overall stiffness, while the localized stiffening broadens the frequency response. The piezoelectric film is integrated through a transfer process that employs a donor substrate. We evaluate functionality through electrical, mechanical, acoustic, and optical measurements, including sound pressure level and resonance frequency, in both open field and in-ear conditions. The results confirm the device’s ability to operate under different acoustic loads and demonstrate compatibility of the fabrication process with flexible and transparent substrates. This approach enables the integration of transparent piezoelectric actuators and is suitable for compact, bendable, and optically transparent audio systems.

In this paper, we present the modeling and characterization of AlN-based piezoelectric micromachined ultrasonic transducers (PMUTs) dedicated to biomedical applications. Our study encompasses detailed analytical modeling of these transducers in both air and water environments. The model is confronted with finite element simulations that account for realistic issues such as imperfect clamping. To validate the model’s relevance, we compare its predictions with results from optical, electrical, and acoustical characterization. This comprehensive approach provides a robust framework for understanding PMUT behavior and facilitates efficient modeling of future devices.