MEMS Acoustic Sensor Technologies

Microelectromechanical systems acoustic sensors have transformed sound detection by integrating microscopic diaphragms with signal-processing electronics on a single chip. These devices employ capacitive, piezoelectric, electrodynamic or thermoacoustic transduction mechanisms to convert pressure fluctuations into electrical signals. Advances in microfabrication and thin-film materials have enabled the production of sensors with minimal footprints, low power consumption and high sensitivity across audio and ultrasonic bands. Design strategies to alleviate diaphragm stress, optimise backplate geometry and control cavity dimensions have led to improved frequency response, reduced noise and enhanced linearity. Bio-inspired architectures, modelled on the hearing apparatus of the Ormia fly, have yielded compact directional sensors capable of sub-degree localisation accuracy. Such technologies underpin a wide range of applications—from consumer electronics and hearing aids to environmental monitoring and industrial diagnostics—while ongoing developments in broadband detection and machine-learning integration promise further gains in performance and functionality.

Research from Nature Portfolio

Recent studies have demonstrated a miniature directional sensor inspired by the coupled ears of a parasitic fly. This design features two mechanically linked wings that resonate in bending mode around 1.7 kHz, producing a cosine-like directional pattern with angle uncertainty below 0.3° near the normal axis and under 3.4° at ±60°, and an output sensitivity around 25 V/Pa. Building on this, a bio-inspired piezoelectric microphone employs torsional beam coupling to achieve broadband sound source localisation across key audio bands. By carefully optimising diaphragm geometry and etching the substrate underside, the device attains cosine-dependent directionality and an equivalent-input noise under 26 dB SPL, demonstrating practical suitability for low-noise hearing-aid applications and real-world acoustic scene analysis.

Research from all publishers

A comprehensive review of MEMS capacitive microphones has collated four decades of innovation, analysing trends in diaphragm materials, backplate protrusion designs and chamber architectures, and benchmarking performance parameters such as sensitivity, noise floor and bandwidth. In a separate development, a semiconstrained polysilicon diaphragm supported by central and peripheral backplate protrusions achieved an 85 % increase in effective diaphragm area, yielding a sensitivity of –38 dB (ref. 1 V/Pa at 1 kHz) and an SNR of 67 dBA within a 3.25 mm × 1.9 mm × 0.9 mm packaged ASIC. Furthermore, an electret-augmented electrostatic actuator has been shown to generate 50 dB SPL in out-of-plane motion using only an AC drive, thanks to integrated quasi-permanent charge, pointing to low-power microspeaker applications without external bias circuitry.

MEMS Acoustic Sensor Technologies publication trend

The graph below shows the total number of articles in mems acoustic sensor technologies across all publications each year (not limited to Nature Index journals).

Technical terms

Microelectromechanical systems (MEMS): Miniaturised devices combining mechanical structures with electronic circuits on a single chip.

Capacitive transduction: Conversion of sound-induced diaphragm deflection into electrical signals via changes in capacitance between a diaphragm and backplate.

Piezoelectric transduction: Generation of electrical charge from mechanical strain in piezoelectric materials under acoustic excitation.

Resonance frequency: The frequency at which a sensor’s mechanical structure exhibits maximal vibration amplitude.

Signal-to-noise ratio (SNR): The ratio of desired signal level to background noise level, expressed in decibels.

Directional response: Variation in sensor sensitivity as a function of the incident sound angle.

References

1. Bio-Inspired Miniature Direction Finding Acoustic Sensor. Scientific Reports (2016).
2. Sound source localization by Ormia ochracea inspired low–noise piezoelectric MEMS directional microphone. Scientific Reports (2020).
3. A Review of MEMS Capacitive Microphones. Micromachines (2020).
4. A Novel MEMS Capacitive Microphone with Semiconstrained Diaphragm Supported with Center and Peripheral Backplate Protrusions. Micromachines (2021).
5. An Electret-Augmented Low-Voltage MEMS Electrostatic Out-of-Plane Actuator for Acoustic Transducer Applications. Micromachines (2020).