Design considerations and performance of MEMS acoustoelectric ultrasound detectors

Zhaohui Wang, Pier Ingram, Charles L. Greenlee, Ragnar Olafsson, Robert A Norwood, Russell S Witte

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure. The device exploits the AE effect, an interaction between electrical current flowing through a material and a propagating pressure wave. Previous designs required imprecise fabrication methods using common laboratory supplies, making it difficult to control basic features such as shape and size. This study describes a different approach based on microelectromechanical systems (MEMS) processing that allows for much finer control of several design features. In an effort to improve the performance of the AE hydrophone, we combine simulations with bench-top testing to evaluate key design features, such as thickness, shape, and conductivity of the active and passive elements. The devices were evaluated in terms of sensitivity, frequency response, and accuracy for reproducing the beam pattern. Our simulations and experimental results both indicated that designs using a combination of indium tin oxide (ITO) for the active element and gold for the passive electrodes (conductivity ratio = ~20) produced the best result for mapping the beam of a 2.25-MHz ultrasound transducer. Also, the AE hydrophone with a rectangular dumbbell configuration achieved a better beam pattern than other shape configurations. Lateral and axial resolutions were consistent with images generated from a commercial capsule hydrophone. Sensitivity of the bestperforming device was 1.52 nV/Pa at 500 kPa using a bias voltage of 20 V. We expect a thicker AE hydrophone closer to half the acoustic wavelength to produce even better sensitivity, while maintaining high spectral bandwidth for characterizing medical ultrasound transducers. AE ultrasound detectors may also be useful for monitoring acoustic exposure during therapy or as receivers for photoacoustic imaging.

Original languageEnglish (US)
Article number6587399
Pages (from-to)1906-1916
Number of pages11
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume60
Issue number9
DOIs
StatePublished - 2013

Fingerprint

Hydrophones
hydrophones
microelectromechanical systems
MEMS
Ultrasonics
Detectors
detectors
Acoustics
sensitivity
acoustics
Transducers
Acoustoelectric effects
transducers
bandwidth
Bandwidth
conductivity
Photoacoustic effect
Monitoring
Piezoelectric materials
capsules

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Acoustics and Ultrasonics
  • Instrumentation

Cite this

Design considerations and performance of MEMS acoustoelectric ultrasound detectors. / Wang, Zhaohui; Ingram, Pier; Greenlee, Charles L.; Olafsson, Ragnar; Norwood, Robert A; Witte, Russell S.

In: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 60, No. 9, 6587399, 2013, p. 1906-1916.

Research output: Contribution to journalArticle

@article{0c4c0227e091424da87d412047272daf,
title = "Design considerations and performance of MEMS acoustoelectric ultrasound detectors",
abstract = "Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure. The device exploits the AE effect, an interaction between electrical current flowing through a material and a propagating pressure wave. Previous designs required imprecise fabrication methods using common laboratory supplies, making it difficult to control basic features such as shape and size. This study describes a different approach based on microelectromechanical systems (MEMS) processing that allows for much finer control of several design features. In an effort to improve the performance of the AE hydrophone, we combine simulations with bench-top testing to evaluate key design features, such as thickness, shape, and conductivity of the active and passive elements. The devices were evaluated in terms of sensitivity, frequency response, and accuracy for reproducing the beam pattern. Our simulations and experimental results both indicated that designs using a combination of indium tin oxide (ITO) for the active element and gold for the passive electrodes (conductivity ratio = ~20) produced the best result for mapping the beam of a 2.25-MHz ultrasound transducer. Also, the AE hydrophone with a rectangular dumbbell configuration achieved a better beam pattern than other shape configurations. Lateral and axial resolutions were consistent with images generated from a commercial capsule hydrophone. Sensitivity of the bestperforming device was 1.52 nV/Pa at 500 kPa using a bias voltage of 20 V. We expect a thicker AE hydrophone closer to half the acoustic wavelength to produce even better sensitivity, while maintaining high spectral bandwidth for characterizing medical ultrasound transducers. AE ultrasound detectors may also be useful for monitoring acoustic exposure during therapy or as receivers for photoacoustic imaging.",
author = "Zhaohui Wang and Pier Ingram and Greenlee, {Charles L.} and Ragnar Olafsson and Norwood, {Robert A} and Witte, {Russell S}",
year = "2013",
doi = "10.1109/TUFFC.2013.2775",
language = "English (US)",
volume = "60",
pages = "1906--1916",
journal = "IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control",
issn = "0885-3010",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "9",

}

TY - JOUR

T1 - Design considerations and performance of MEMS acoustoelectric ultrasound detectors

AU - Wang, Zhaohui

AU - Ingram, Pier

AU - Greenlee, Charles L.

AU - Olafsson, Ragnar

AU - Norwood, Robert A

AU - Witte, Russell S

PY - 2013

Y1 - 2013

N2 - Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure. The device exploits the AE effect, an interaction between electrical current flowing through a material and a propagating pressure wave. Previous designs required imprecise fabrication methods using common laboratory supplies, making it difficult to control basic features such as shape and size. This study describes a different approach based on microelectromechanical systems (MEMS) processing that allows for much finer control of several design features. In an effort to improve the performance of the AE hydrophone, we combine simulations with bench-top testing to evaluate key design features, such as thickness, shape, and conductivity of the active and passive elements. The devices were evaluated in terms of sensitivity, frequency response, and accuracy for reproducing the beam pattern. Our simulations and experimental results both indicated that designs using a combination of indium tin oxide (ITO) for the active element and gold for the passive electrodes (conductivity ratio = ~20) produced the best result for mapping the beam of a 2.25-MHz ultrasound transducer. Also, the AE hydrophone with a rectangular dumbbell configuration achieved a better beam pattern than other shape configurations. Lateral and axial resolutions were consistent with images generated from a commercial capsule hydrophone. Sensitivity of the bestperforming device was 1.52 nV/Pa at 500 kPa using a bias voltage of 20 V. We expect a thicker AE hydrophone closer to half the acoustic wavelength to produce even better sensitivity, while maintaining high spectral bandwidth for characterizing medical ultrasound transducers. AE ultrasound detectors may also be useful for monitoring acoustic exposure during therapy or as receivers for photoacoustic imaging.

AB - Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure. The device exploits the AE effect, an interaction between electrical current flowing through a material and a propagating pressure wave. Previous designs required imprecise fabrication methods using common laboratory supplies, making it difficult to control basic features such as shape and size. This study describes a different approach based on microelectromechanical systems (MEMS) processing that allows for much finer control of several design features. In an effort to improve the performance of the AE hydrophone, we combine simulations with bench-top testing to evaluate key design features, such as thickness, shape, and conductivity of the active and passive elements. The devices were evaluated in terms of sensitivity, frequency response, and accuracy for reproducing the beam pattern. Our simulations and experimental results both indicated that designs using a combination of indium tin oxide (ITO) for the active element and gold for the passive electrodes (conductivity ratio = ~20) produced the best result for mapping the beam of a 2.25-MHz ultrasound transducer. Also, the AE hydrophone with a rectangular dumbbell configuration achieved a better beam pattern than other shape configurations. Lateral and axial resolutions were consistent with images generated from a commercial capsule hydrophone. Sensitivity of the bestperforming device was 1.52 nV/Pa at 500 kPa using a bias voltage of 20 V. We expect a thicker AE hydrophone closer to half the acoustic wavelength to produce even better sensitivity, while maintaining high spectral bandwidth for characterizing medical ultrasound transducers. AE ultrasound detectors may also be useful for monitoring acoustic exposure during therapy or as receivers for photoacoustic imaging.

UR - http://www.scopus.com/inward/record.url?scp=84883753252&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84883753252&partnerID=8YFLogxK

U2 - 10.1109/TUFFC.2013.2775

DO - 10.1109/TUFFC.2013.2775

M3 - Article

VL - 60

SP - 1906

EP - 1916

JO - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

JF - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

SN - 0885-3010

IS - 9

M1 - 6587399

ER -