Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849309
W. Walker, L.A. Negron, T. Mondzelewski, M. J. McAllister, F. Fernández, C. Toth
Tissue elasticity estimation is a major topic of ultrasound research. While most research focuses on cancer detection, the authors have concentrated on the detection of mechanical changes in the vitreous body of the eye. These changes are believed to contribute to retinal detachment. Thus, an accurate method of imaging vitreous mechanical properties might enable identification of patients at high risk before the presentation of symptoms. The authors are developing a new method of vitreous imaging which attempts to image tissue stiffness by applying acoustic radiation force. Force is applied at either a single location or along a line, with resultant target displacements estimated from returned echoes. This approach yields the dynamic response of targets to the applied forces. Images can be formed of the maximum induced displacement, or the relative elasticity and relative viscosity found by fitting experimental data to the Voigt model. The authors present B-Mode, maximum displacement, relative elasticity, and relative viscosity images of tissue mimicking phantoms and an enzymatically modified porcine eye. Images show the expected correlation between material stiffness and measured displacement. The potential of radiation force imaging was further explored by using a clinical ultrasound system to interrogate a phantom. At 84 mW/cm/sup 2/ small displacements were visible in the B-Mode image, suggesting that measurable displacements may be generated at 50 mW/cm/sup 2/, the historical FDA ophthalmic power limit.
{"title":"Imaging the stiffness of the vitreous body with acoustic radiation force","authors":"W. Walker, L.A. Negron, T. Mondzelewski, M. J. McAllister, F. Fernández, C. Toth","doi":"10.1109/ULTSYM.1999.849309","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849309","url":null,"abstract":"Tissue elasticity estimation is a major topic of ultrasound research. While most research focuses on cancer detection, the authors have concentrated on the detection of mechanical changes in the vitreous body of the eye. These changes are believed to contribute to retinal detachment. Thus, an accurate method of imaging vitreous mechanical properties might enable identification of patients at high risk before the presentation of symptoms. The authors are developing a new method of vitreous imaging which attempts to image tissue stiffness by applying acoustic radiation force. Force is applied at either a single location or along a line, with resultant target displacements estimated from returned echoes. This approach yields the dynamic response of targets to the applied forces. Images can be formed of the maximum induced displacement, or the relative elasticity and relative viscosity found by fitting experimental data to the Voigt model. The authors present B-Mode, maximum displacement, relative elasticity, and relative viscosity images of tissue mimicking phantoms and an enzymatically modified porcine eye. Images show the expected correlation between material stiffness and measured displacement. The potential of radiation force imaging was further explored by using a clinical ultrasound system to interrogate a phantom. At 84 mW/cm/sup 2/ small displacements were visible in the B-Mode image, suggesting that measurable displacements may be generated at 50 mW/cm/sup 2/, the historical FDA ophthalmic power limit.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121400363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849313
C. Sumi, M. Kubota
The authors developed a suitable ultrasonic (US) strain-measurement-based shear modulus reconstruction method for superficial tissues. The suitability was demonstrated on in vitro pork rib and in vivo breast tissues.
{"title":"Method demonstration on shear modulus reconstruction on superficial tissues","authors":"C. Sumi, M. Kubota","doi":"10.1109/ULTSYM.1999.849313","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849313","url":null,"abstract":"The authors developed a suitable ultrasonic (US) strain-measurement-based shear modulus reconstruction method for superficial tissues. The suitability was demonstrated on in vitro pork rib and in vivo breast tissues.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121427825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849276
D. Kruse, R. Silverman, D. Coleman, S. Erickson, K. Ferrara
A new high frequency ultrasound system has been developed to visualize and measure blood flow parameters in the superficial microvasculature with a resolution of 40 /spl mu/m. A recently reported method (D.E. Kruse et al., 1998, R.H. Silverman et al., 1999), which the authors call swept-scan or swept Doppler, has been developed to rapidly acquire 2-D frames data for blood velocity estimation using sweeping scans of a single element focused transducer. Using this new method combined with the M-mode technique, experiments were performed to quantify blood flow in the highly vascular, anterior segment of the eye. Scans of radial vessels in the rabbit iris indicate that blood flow can be mapped in arterioles down to 40 /spl mu/m in diameter with velocities as low as 0.5 mm/sec. Furthermore, preliminary estimates of the effect of vasoactive drugs show that blood flow changes due to application of topical atropine can be measured in the 200 /spl mu/m rabbit major arterial circle with both M-mode and swept-scan techniques. In particular, the M-mode technique was sufficiently sensitive to detect changes in peak systolic and diastolic blood flow, and these velocity measurements were consistent with those obtained from the swept-scan.
{"title":"High resolution blood flow mapping in the anterior segment of the eye","authors":"D. Kruse, R. Silverman, D. Coleman, S. Erickson, K. Ferrara","doi":"10.1109/ULTSYM.1999.849276","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849276","url":null,"abstract":"A new high frequency ultrasound system has been developed to visualize and measure blood flow parameters in the superficial microvasculature with a resolution of 40 /spl mu/m. A recently reported method (D.E. Kruse et al., 1998, R.H. Silverman et al., 1999), which the authors call swept-scan or swept Doppler, has been developed to rapidly acquire 2-D frames data for blood velocity estimation using sweeping scans of a single element focused transducer. Using this new method combined with the M-mode technique, experiments were performed to quantify blood flow in the highly vascular, anterior segment of the eye. Scans of radial vessels in the rabbit iris indicate that blood flow can be mapped in arterioles down to 40 /spl mu/m in diameter with velocities as low as 0.5 mm/sec. Furthermore, preliminary estimates of the effect of vasoactive drugs show that blood flow changes due to application of topical atropine can be measured in the 200 /spl mu/m rabbit major arterial circle with both M-mode and swept-scan techniques. In particular, the M-mode technique was sufficiently sensitive to detect changes in peak systolic and diastolic blood flow, and these velocity measurements were consistent with those obtained from the swept-scan.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125277388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849522
N. C. Chaggares, R. K. Tang, A. Sinclair, F. Foster, K. Haraieciwz, B. Starkoski
Ultrasonic testing systems commonly employ voltage limiters to protect the display unit or pre-amp from the large pulses used to excite the transducers. These voltage limiters can seriously distort the shapes of echo signals, and degrade time resolution in signals centered above 30 MHz. The potential to avoid these problems by replacing the limiter with a fast high-voltage switching circuit is measured for two experimental systems.
{"title":"Protection circuitry and time resolution in high frequency ultrasonic NDE","authors":"N. C. Chaggares, R. K. Tang, A. Sinclair, F. Foster, K. Haraieciwz, B. Starkoski","doi":"10.1109/ULTSYM.1999.849522","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849522","url":null,"abstract":"Ultrasonic testing systems commonly employ voltage limiters to protect the display unit or pre-amp from the large pulses used to excite the transducers. These voltage limiters can seriously distort the shapes of echo signals, and degrade time resolution in signals centered above 30 MHz. The potential to avoid these problems by replacing the limiter with a fast high-voltage switching circuit is measured for two experimental systems.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122666217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849298
M. Defontaine, D. Certon, L. Colin, C. Yvon, P. Vince, E. Lacaze, R. Dufait, E. Camus, P. Laugier, F. Patat
In the context of a European Space Agency Technical Research Program, focused on bone activities in micro gravity environment, Matra Marconi Space, Vermon, LIP, ULTRASONS TECHNOLOGIES and GIP Ultrasons have been asked to develop a prototype of an ultrasonic 2D array bone densitometer. This transmission device is composed of two matrices of 24/spl times/24 elements and is functioning at 500 kHz central frequency. The test objects are scanned over a 60/spl times/60 mm/sup 2/ with an active aperture of 30 mm diameter. After the acquisition and reconstruction step, the signals are processed to extract two parametric images of attenuation and celerity. The first experiments, reported in this paper have been performed in immersion. Parametric images of in-vitro phantoms and in-vivo heel bone are presented.
{"title":"A prototype of a 500 kHz ultrasonic matricial device: beam scanner. Application to in-vivo heel bone quantitative characterization","authors":"M. Defontaine, D. Certon, L. Colin, C. Yvon, P. Vince, E. Lacaze, R. Dufait, E. Camus, P. Laugier, F. Patat","doi":"10.1109/ULTSYM.1999.849298","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849298","url":null,"abstract":"In the context of a European Space Agency Technical Research Program, focused on bone activities in micro gravity environment, Matra Marconi Space, Vermon, LIP, ULTRASONS TECHNOLOGIES and GIP Ultrasons have been asked to develop a prototype of an ultrasonic 2D array bone densitometer. This transmission device is composed of two matrices of 24/spl times/24 elements and is functioning at 500 kHz central frequency. The test objects are scanned over a 60/spl times/60 mm/sup 2/ with an active aperture of 30 mm diameter. After the acquisition and reconstruction step, the signals are processed to extract two parametric images of attenuation and celerity. The first experiments, reported in this paper have been performed in immersion. Parametric images of in-vitro phantoms and in-vivo heel bone are presented.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131530666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849502
J. de Rosny, A. Tourin, M. Fink
We report the first evidence of Coherent Backscattering Enhancement for transient elastic waves propagating in a two dimensional chaotic cavity. The intensity at the point source is twice larger than at any other points around the source. Unlike optical experiments, this effect is clearly observable in acoustics on a single realization.
{"title":"Coherent backscattering for elastic waves in a chaotic cavity","authors":"J. de Rosny, A. Tourin, M. Fink","doi":"10.1109/ULTSYM.1999.849502","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849502","url":null,"abstract":"We report the first evidence of Coherent Backscattering Enhancement for transient elastic waves propagating in a two dimensional chaotic cavity. The intensity at the point source is twice larger than at any other points around the source. Unlike optical experiments, this effect is clearly observable in acoustics on a single realization.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131532468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849403
H. Ieki, M. Kadota
Sezawa wave on a ZnO/sapphire substrate is applied to low insertion loss surface acoustic wave (SAW) filters in microwave band of 1.5 GHz to 2.5 GHz range. RF planar magnetron sputtering (RF-Mg) is used for the fabrication of epitaxial ZnO film. Sputtering conditions and the dopant are decided to realize a stable and reproducible process. Details of ZnO epitaxial growth and practical application results are reviewed. To improve the piezoelectric properties of ZnO film, electron cyclotron resonance (ECR) sputtering is investigated. The ZnO/quartz substrate has small temperature coefficient of frequency (TCF) and medium electromechanical coupling coefficient (ks) comparable to ST cut quartz and Li2B4O7 respectively. Theoretical and experimental results are also discussed.
{"title":"ZnO thin films for high frequency SAW devices","authors":"H. Ieki, M. Kadota","doi":"10.1109/ULTSYM.1999.849403","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849403","url":null,"abstract":"Sezawa wave on a ZnO/sapphire substrate is applied to low insertion loss surface acoustic wave (SAW) filters in microwave band of 1.5 GHz to 2.5 GHz range. RF planar magnetron sputtering (RF-Mg) is used for the fabrication of epitaxial ZnO film. Sputtering conditions and the dopant are decided to realize a stable and reproducible process. Details of ZnO epitaxial growth and practical application results are reviewed. To improve the piezoelectric properties of ZnO film, electron cyclotron resonance (ECR) sputtering is investigated. The ZnO/quartz substrate has small temperature coefficient of frequency (TCF) and medium electromechanical coupling coefficient (ks) comparable to ST cut quartz and Li2B4O7 respectively. Theoretical and experimental results are also discussed.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127746239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849275
M.E. Anderson, L. Bohs, S. Gebhart
Spatial quadrature and speckle tracking are both techniques which extend the estimation of flow velocity or tissue motion velocity to two or three dimensions. The authors applied both under similar experimental conditions to assess and compare their performance. They also describe a new spatial quadrature processor that obviates the need for axial alignment under conditions of mixed axial-lateral flow. This processor avoids the estimate bias produced by jitter in the axial alignment step previously described, and thus allows the non-axial component(s) of flow to be tracked without sacrificing axial resolution. In the authors' flow experiment, summed radiofrequency echo data were captured in an M-mode scan geometry using 2:1 parallel receive processing in both spatial quadrature and two-beam speckle tracking configurations using a 7.5 MHz linear array and a modified commercial ultrasound scanner. Laminar flow was established in a wall-less vessel phantom using a computer-controlled pump. The authors captured echo data from this phantom at beam-vessel angles of 60/spl deg/ and 90/spl deg/ (i.e. pure lateral flow). These data were processed off-line to estimate flow velocity profiles. Volume flow rates were calculated from these profiles by integration. The mean volume flow rates estimated with 2-D speckle tracking agreed with the known flow rates with a maximum relative error of 7% for true lateral flow and 10% for mixed axial-lateral flow. The equivalent values for spatial quadrature were 5% and 15%.
{"title":"A comparison of flow tracking techniques: spatial quadrature with phase-sensitive axial demodulation versus speckle tracking","authors":"M.E. Anderson, L. Bohs, S. Gebhart","doi":"10.1109/ULTSYM.1999.849275","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849275","url":null,"abstract":"Spatial quadrature and speckle tracking are both techniques which extend the estimation of flow velocity or tissue motion velocity to two or three dimensions. The authors applied both under similar experimental conditions to assess and compare their performance. They also describe a new spatial quadrature processor that obviates the need for axial alignment under conditions of mixed axial-lateral flow. This processor avoids the estimate bias produced by jitter in the axial alignment step previously described, and thus allows the non-axial component(s) of flow to be tracked without sacrificing axial resolution. In the authors' flow experiment, summed radiofrequency echo data were captured in an M-mode scan geometry using 2:1 parallel receive processing in both spatial quadrature and two-beam speckle tracking configurations using a 7.5 MHz linear array and a modified commercial ultrasound scanner. Laminar flow was established in a wall-less vessel phantom using a computer-controlled pump. The authors captured echo data from this phantom at beam-vessel angles of 60/spl deg/ and 90/spl deg/ (i.e. pure lateral flow). These data were processed off-line to estimate flow velocity profiles. Volume flow rates were calculated from these profiles by integration. The mean volume flow rates estimated with 2-D speckle tracking agreed with the known flow rates with a maximum relative error of 7% for true lateral flow and 10% for mixed axial-lateral flow. The equivalent values for spatial quadrature were 5% and 15%.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133188062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849447
C. S. Lee, K. No, D. Wee, J. H. Lee, C. Choi
We designed and fabricated the silicon micromachined flexural plate wave actuator based on piezoelectric PbZrxTi1-xO3 (PZT) thin films for use in angular rate sensor. The working principles of the angular rate sensor utilizing the wave were investigated.
{"title":"A novel angular rate sensor employing flexural plate wave","authors":"C. S. Lee, K. No, D. Wee, J. H. Lee, C. Choi","doi":"10.1109/ULTSYM.1999.849447","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849447","url":null,"abstract":"We designed and fabricated the silicon micromachined flexural plate wave actuator based on piezoelectric PbZr<sub>x</sub>Ti<sub>1-x</sub>O<sub>3</sub> (PZT) thin films for use in angular rate sensor. The working principles of the angular rate sensor utilizing the wave were investigated.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133304871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-17DOI: 10.1109/ULTSYM.1999.849199
K. Niederer, P. Eccardt, H. Meixner, R. Lerch
Due to their low membrane mass capacitive Micromachined Ultrasound Transducers (cMUTs) are very well matched to fluid loads. Besides the excellent transducer performance the good matching leads to an increased acoustic coupling between adjacent membranes and consequently to out of phase modes. These modes are lateral resonances of surface waves with a high quality factor. A method for suppressing the undesirable resonances has been developed and experimental results for the new transducer design are presented. The force of the electrostatic transducer increases with the square of the electric field in the gap. Due to their small gap spacing cMUTs can produce high sound pressures. Here we show how this spacing can be reduced beyond the limit of the CMOS fabrication process. On the other hand, the nonlinear force produces harmonic distortion. A procedure to find designs combining maximum sound pressure with minimum distortion has been developed. As a result, the sound pressure and according design parameters as a function of the distortion are discussed.
{"title":"Micromachined transducer design for minimized generation of surface waves","authors":"K. Niederer, P. Eccardt, H. Meixner, R. Lerch","doi":"10.1109/ULTSYM.1999.849199","DOIUrl":"https://doi.org/10.1109/ULTSYM.1999.849199","url":null,"abstract":"Due to their low membrane mass capacitive Micromachined Ultrasound Transducers (cMUTs) are very well matched to fluid loads. Besides the excellent transducer performance the good matching leads to an increased acoustic coupling between adjacent membranes and consequently to out of phase modes. These modes are lateral resonances of surface waves with a high quality factor. A method for suppressing the undesirable resonances has been developed and experimental results for the new transducer design are presented. The force of the electrostatic transducer increases with the square of the electric field in the gap. Due to their small gap spacing cMUTs can produce high sound pressures. Here we show how this spacing can be reduced beyond the limit of the CMOS fabrication process. On the other hand, the nonlinear force produces harmonic distortion. A procedure to find designs combining maximum sound pressure with minimum distortion has been developed. As a result, the sound pressure and according design parameters as a function of the distortion are discussed.","PeriodicalId":339424,"journal":{"name":"1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133496519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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