Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers

Capacitive micromachined ultrasonic transducers (CMUTs) have been developed for air-coupled applications to address key challenges such as noise, prolonged ringing, and side-lobe interference. This study introduces an optimized CMUT design that leverages the squeeze-film damping effect to achieve a...

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Main Authors: Amirhossein Moshrefi, Abid Ali, Mathieu Gratuze, Frederic Nabki
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Micromachines
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Online Access:https://www.mdpi.com/2072-666X/16/7/797
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author Amirhossein Moshrefi
Abid Ali
Mathieu Gratuze
Frederic Nabki
author_facet Amirhossein Moshrefi
Abid Ali
Mathieu Gratuze
Frederic Nabki
author_sort Amirhossein Moshrefi
collection DOAJ
description Capacitive micromachined ultrasonic transducers (CMUTs) have been developed for air-coupled applications to address key challenges such as noise, prolonged ringing, and side-lobe interference. This study introduces an optimized CMUT design that leverages the squeeze-film damping effect to achieve a low-quality factor, enhancing resolution and temporal precision for imaging as one of the suggested airborne application. The device was fabricated using the PolyMUMPs process, ensuring high structural accuracy and consistency. Finite element analysis (FEA) simulations validated the optimized parameters, demonstrating improved displacement, reduced side-lobe artifacts, and sharper main lobes for superior imaging performance. Experimental validation, including Laser Doppler Vibrometer (LDV) measurements of membrane displacement and mode shapes, along with ring oscillation tests to assess Q-factor and signal decay, confirmed the device’s reliability and consistency across four CMUT arrays. Additionally, this study explores the implementation of multi-frequency CMUT arrays, enhancing imaging versatility across different air-coupled applications. By integrating multiple frequency bands, the proposed CMUTs enable adaptable imaging focus, improving their suitability for diverse diagnostic scenarios. These advancements highlight the potential of the proposed design to deliver a superior performance for airborne applications, paving the way for its integration into advanced diagnostic systems.
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spelling doaj-art-7db947b7ee584dab8d0cd004d04bf5602025-08-20T03:36:12ZengMDPI AGMicromachines2072-666X2025-07-0116779710.3390/mi16070797Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic TransducersAmirhossein Moshrefi0Abid Ali1Mathieu Gratuze2Frederic Nabki3Department of Electrical Engineering, École de Technologie Supérieure (ETS), Montreal, QC H3C 1K3, CanadaDepartment of Electrical Engineering, École de Technologie Supérieure (ETS), Montreal, QC H3C 1K3, CanadaDepartment of Electrical Engineering, École de Technologie Supérieure (ETS), Montreal, QC H3C 1K3, CanadaDepartment of Electrical Engineering, École de Technologie Supérieure (ETS), Montreal, QC H3C 1K3, CanadaCapacitive micromachined ultrasonic transducers (CMUTs) have been developed for air-coupled applications to address key challenges such as noise, prolonged ringing, and side-lobe interference. This study introduces an optimized CMUT design that leverages the squeeze-film damping effect to achieve a low-quality factor, enhancing resolution and temporal precision for imaging as one of the suggested airborne application. The device was fabricated using the PolyMUMPs process, ensuring high structural accuracy and consistency. Finite element analysis (FEA) simulations validated the optimized parameters, demonstrating improved displacement, reduced side-lobe artifacts, and sharper main lobes for superior imaging performance. Experimental validation, including Laser Doppler Vibrometer (LDV) measurements of membrane displacement and mode shapes, along with ring oscillation tests to assess Q-factor and signal decay, confirmed the device’s reliability and consistency across four CMUT arrays. Additionally, this study explores the implementation of multi-frequency CMUT arrays, enhancing imaging versatility across different air-coupled applications. By integrating multiple frequency bands, the proposed CMUTs enable adaptable imaging focus, improving their suitability for diverse diagnostic scenarios. These advancements highlight the potential of the proposed design to deliver a superior performance for airborne applications, paving the way for its integration into advanced diagnostic systems.https://www.mdpi.com/2072-666X/16/7/797ultrasonic sensorquality factor optimizationarray designCMUTMEMS
spellingShingle Amirhossein Moshrefi
Abid Ali
Mathieu Gratuze
Frederic Nabki
Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers
Micromachines
ultrasonic sensor
quality factor optimization
array design
CMUT
MEMS
title Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers
title_full Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers
title_fullStr Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers
title_full_unstemmed Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers
title_short Design and Fabrication of Multi-Frequency and Low-Quality-Factor Capacitive Micromachined Ultrasonic Transducers
title_sort design and fabrication of multi frequency and low quality factor capacitive micromachined ultrasonic transducers
topic ultrasonic sensor
quality factor optimization
array design
CMUT
MEMS
url https://www.mdpi.com/2072-666X/16/7/797
work_keys_str_mv AT amirhosseinmoshrefi designandfabricationofmultifrequencyandlowqualityfactorcapacitivemicromachinedultrasonictransducers
AT abidali designandfabricationofmultifrequencyandlowqualityfactorcapacitivemicromachinedultrasonictransducers
AT mathieugratuze designandfabricationofmultifrequencyandlowqualityfactorcapacitivemicromachinedultrasonictransducers
AT fredericnabki designandfabricationofmultifrequencyandlowqualityfactorcapacitivemicromachinedultrasonictransducers