Piezoelectric Micromachined Ultrasonic Transducer-Integrated Helmholtz Resonator with Microliter-Sized Volume-Tunable Cavity

In this study, a piezoelectric micromachined ultrasonic transducer (PMUT) is integrated with a microliter-sized volume-tunable Helmholtz resonator. The passive Helmholtz resonator is constructed using an SU8 photolithography-defined square opening plate as the neck portion, a 3D-printed hollow struc...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2022-10, Vol.22 (19), p.7471
Main Authors: Feng, Guo-Hua, Chen, Wen-Sheng
Format: Article
Language:English
Subjects:
Acoustics
Actuators
Bandwidths
Cavity resonators
Design
Electrodes
Energy
Equipment Design
Helmholtz resonator
Helmholtz resonators
Micromachining
Parameter modification
Photolithography
piezoelectric film
Piezoelectric films
Potash
Potassium
Power series
Pressure
Silver
Simulation
Sound pressure
Titanium
Transducers
two-term power series curve
ultrasonic
Ultrasonic transducers
Ultrasonics
volume-tunable cavity
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Summary:In this study, a piezoelectric micromachined ultrasonic transducer (PMUT) is integrated with a microliter-sized volume-tunable Helmholtz resonator. The passive Helmholtz resonator is constructed using an SU8 photolithography-defined square opening plate as the neck portion, a 3D-printed hollow structure with a threaded insert nut, and a precision set screw to form the volume-controllable cavity of the Helmholtz resonator. The fabricated piezoelectric films acted as ultrasonic actuators attached to the surface of the neck SU8 plate. Experimental results show that the sound pressure level (SPL) and operation bandwidth could be effectively tuned, and a 200% SPL increase and twofold bandwidth enhancement are achieved when setting the cavity length to 0.75 mm compared with the open-cavity case. A modified Helmholtz resonator model is proposed to explain the experimental results. The adjusting factors of the effective mass and viscous damper are created to modify the existing parameters in the conventional Helmholtz resonator model. The relationship between the adjusting factors and cavity length can be described well using a two-term power series curve. This modified Helmholtz resonator model not only provides insight into this active-type Helmholtz resonator operation but also provides a useful estimation for its optimal design and fabrication.
ISSN:1424-8220
1424-8220
DOI:10.3390/s22197471