The MEMS microphone is a representative device among the MEMS family, which has attracted substantial research interest, and those tailored for human voice have earned distinct success in commercialization. Although sustained development persists, challenges such as residual stress, environmental noise, and structural innovation are posed. To collect and summarize the recent advances in this subject, this paper presents a concise review concerning the transduction mechanism, diverse mechanical structure topologies, and effective methods of noise reduction for high-performance MEMS microphones with a dynamic range akin to the audible spectrum, aiming to provide a comprehensive and adequate analysis of this scope.

This letter conducts a thorough comparison between two temperature compensation methods for resonant micro-electro-mechanical-system (MEMS) sensors, i.e., 1) a newly proposed in-situ temperature compensation technique based on a multiple parameter decoupling (MPD) using a single resonant MEMS sensor subject to blue-sideband excitation, and 2) the prevailing method utilizing a temperature sensor, which, in this letter, is a resonant thermometer in close vicinity of the sensor. Experimental results show that the MPD-based in-situ temperature compensation method offers better noise performance, long-term stability (fourfold at 1000s integration time) and application simplicity, compared with the compensation method using an additional thermometer, affirming that the proposed subject is of considerable potential for true in-situ temperature compensation for high-precision resonant MEMS sensors.

This work introduces a novel tunable piezoelectric MEMS microphone, featuring a fully clamped membrane and dual-sensing electrodes. The device achieves a baseline sensitivity of -39.31 dB, with tunability enabled by a DC tuning mechanism. The key innovations of this subject include: 1) a discrete electrode design enabling simultaneous tuning of sensitivity and resonant frequency while preserving acoustic sensing functionality; 2)utilizing the reverse piezoelectric effect to achieve large tunable ranges with minimal tuning voltages; and 3) a cost-effective performance tuning methodology that eliminates the need for structural modifications; 4) ascertain the tuning mechanism. Furthermore, a refined equivalent circuit model provides insights into the electromechanical behavior of the device, enabling the optimization of tunable microphones and acoustic transducers. Experimental results demonstrate the tuning ability successfully. The acoustic experiment shows that the output amplitude can be changed by up to 182.18% under ±0.5 V DC tuning under 1 kHz acoustic input. The electrical experiment reveals a maximum resonant frequency change of 6.85% with ±10 V DC. The proposed microphone is a promising candidate to be employed in many next-generation audio applications, such as adaptive voice systems, AI-driven speech recognition, and noise cancellation.[2025-0005]

This study introduces a bio-inspired AlN-piezoelectric MEMS microphone that showcases a cantilever structure offering adjustable performance, fully emulating the dynamics and tunability observed in the basilar membrane of the mammalian cochlea. Through the incorporation of piezoelectric and converse piezoelectric effects alongside dual parametric modulation mechanisms, the device successfully replicates three crucial aspects of cochlear mechanics: i) sensory transduction characteristic of inner hair cell (IHC); ii) local stiffness modulation enabled by outer hair cell (OHC) somatic motility; and iii) energy redistribution in coupled-system recapitulating the energy transfer of cochlear traveling wave dynamics. The device performance was systematically characterized through electrical characterizations, optical analysis, and acoustic measurements. Experimental results demonstrate a baseline sensitivity of −25.38 dB/Pa and signal-to-noise ratios up to 79.28 dB within an operation bandwidth from 1.755 to 2.261 kHz (3 dB cut-on and cut-off bandwidth), while the quality factor (Q) can be tuned to a value ranging from −55.38% to 180.10% of initial values, representing a 124.72% tuning span. In essence, the critical innovations encompass: i) a MEMS microphone that pioneers the first fully mimicking simultaneous sensing/tuning functionality of the mammalian cochlea, through piezoelectric and converse piezoelectric effects; ii) a combination of two novel tuning mechanisms, i.e., AC (through parametric modulation) and mechanical coupling, are applied without the necessity for mechanical structure modification. It can be envisioned that such a technology enables next-generation hearing aids with bio-inspired auditory adaptation, bridging a critical gap in prosthetic sound processing, while also catering to the ever-increasing demands of intelligent acoustic sensors.

This study introduces a novel Aluminum Nitride (AlN) piezoelectric MEMS microphone featuring a piezoelectric layer segmentation comprising a circular, fully clamped membrane and multiple circular patterned electrodes. The innovative design achieves simultaneous multi-readout metrics without complex structures, size factors, or challenging manufacturing processes. By leveraging the unique single diaphragm mode-localization-like behavior of the architecture, the performance of the proposed subject is significantly enhanced. The proposed microphone was systematically characterized through electrical measurements and acoustic validation, demonstrating a distinct improvement in acoustic sensitivity compared to conventional counterparts. Baseline experiments over an acoustic pressure range of 0.16 Pa to 1.42 Pa show that the sensitivities measured by the outer electrodes of the proposed subject outperform those of the reference microphone, with the highest sensitivity reaching 66.74 ± 3.18 μV/Pa. Additionally, the sensitivities of the three inner electrodes were consistent across both devices, with the discrepancy being only 9.39 μV/Pa. The electrical characterization results reveal a weak coupling phenomenon in the first modal of the proposed device due to the engineered piezoelectric layer segmentation, facilitating a foundation for the mode-localization-like dynamics. As such, simultaneous multi-readout schemes can be garnered with respect to various acoustic disturbances, particularly encompassing infrasound regime (<1 Hz), i.e., amplitude modulation (AM), frequency modulation (FM), magnitude ratio (MR), frequency ratio (FR) and cross ratio (CR), in terms of both relative (Rel.) sensitivities and absolute (Abs.) sensitivities. Remarkably, a resolution of 16.24 nPa @ 1 Hz is achieved using the FR readout method, demonstrating a six-order-of-magnitude improvement over the AM metric. These findings underscore the effectiveness of piezoelectric layer segmentation in enhancing the performance of piezoelectric MEMS microphones without necessitating structural modifications or extra interface circuit and providing a pathway for design criteria of next-generation high-performance MEMS acoustic devices.

This article presents a novel multiband piezoelectric microelectromechanical systems (MEMS) microphone. Equipped with a fully clamped membrane and a closed-loop frequency-tracking system, the proposed microphone achieves acoustic signal detection in both infrasonic and audible frequency bands (with an experimentally verified bandwidth of 0.1 Hz–3.8 kHz). Key innovations include: 1) concurrent infrasound and audio-band operation via a single structural design; 2) piezoelectric actuation-enabled mechanical modulation of acoustic signals to support frequency and amplitude modulation (FM/AM) readout in the low-frequency regime; 3) an optimized electrode pattern tailored for low frequencies to enhance FM/AM sensitivities; and 4) cost-effective performance realized using standard piezoelectric MEMS processes. Experimentally, for audible detection, the microphone attains a baseline sensitivity of −52 dB (re 1 V/Pa) and a signal-to-noise ratio (SNR) of 61.1 dB. For low-frequency detection, it exhibits an FM sensitivity of 109.3 mHz/Pa and an AM sensitivity of 51.1 $\boldsymbol{\mu}$ V/Pa, achieving 2.7 $\boldsymbol{\times}$ and 2.2 $\boldsymbol{\times}$ SNR improvements over the unmodulated signal at 20 Hz. With customized configurations, the FM and AM sensitivities are further enhanced to 1198.9 mHz/Pa and 457.6 $\boldsymbol{\mu}$ V/Pa, respectively. The FM enhancement stems from reallocating the original sensing electrode to drive the membrane on the same device, while the AM improvement relies on the revised electrode pattern. These findings demonstrate the device’s great potential as a solution for wearable devices targeting both voice capture and biometric monitoring via subsonic and low-frequency signatures, including heart rate, respiration, and facial movements.