Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193345
T. Watanabe
If the influence of the electrode film thickness is not considered, the propagation loss can suppress the variation quantity by selecting the cut angle of LST-cut at a practical level at the Rayleigh wave level. The problem which should be solved is an electrode film thickness dependency of the leaky surface acoustic wave on LST-cut quartz. IDT is spatially formed as a method of solving this problem, and the method of exciting the leaky surface acoustic wave is examined. The change of the frequency is 20 ppm within the range of the temperature from - 30/spl deg/C to +110/spl deg/C.
{"title":"An approach to perfection of the characteristics of leaky surface acoustic wave on LST-cut quartz","authors":"T. Watanabe","doi":"10.1109/ULTSYM.2002.1193345","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193345","url":null,"abstract":"If the influence of the electrode film thickness is not considered, the propagation loss can suppress the variation quantity by selecting the cut angle of LST-cut at a practical level at the Rayleigh wave level. The problem which should be solved is an electrode film thickness dependency of the leaky surface acoustic wave on LST-cut quartz. IDT is spatially formed as a method of solving this problem, and the method of exciting the leaky surface acoustic wave is examined. The change of the frequency is 20 ppm within the range of the temperature from - 30/spl deg/C to +110/spl deg/C.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124558268","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192510
A. Abrar, S. Cochran
We report a theoretical investigation of multilayer piezoelectric structures with non-uniform layer thicknesses. Our results come from a study of such structures using computer code based on solving the one-dimensional wave equation by matrix manipulation and validation using finite element analysis. We first show how structures with nonuniform layer thicknesses generate even harmonics in their frequency response as well as the odd harmonics generated by devices with uniform layer thicknesses. We have found that control can be exerted over the complete frequency response by appropriate choice of layer thickness. However, for most transducer configurations, the relationship between frequency response and layer thicknesses is very complicated. To overcome this, we have investigated the stochastic optimisation technique of simulated annealing. This allows a transducer configuration to be obtained with a desired frequency response expressed as a cost function. The cost function reported here maximises uniformity of the fundamental and second and third harmonics of output pressure, which we have achieved to approximately /spl plusmn/3%. The results are promising and may deliver additional bandwidth for applications in underwater sonar and biomedical imaging. To illustrate their potential, we also describe a three-layer 1-3 connectivity piezocomposite transducer with a strong response extending over the fundamental and first two harmonics.
{"title":"Mathematical optimisation of multilayer piezoelectric devices with non-uniform layer thicknesses by simulated annealing","authors":"A. Abrar, S. Cochran","doi":"10.1109/ULTSYM.2002.1192510","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192510","url":null,"abstract":"We report a theoretical investigation of multilayer piezoelectric structures with non-uniform layer thicknesses. Our results come from a study of such structures using computer code based on solving the one-dimensional wave equation by matrix manipulation and validation using finite element analysis. We first show how structures with nonuniform layer thicknesses generate even harmonics in their frequency response as well as the odd harmonics generated by devices with uniform layer thicknesses. We have found that control can be exerted over the complete frequency response by appropriate choice of layer thickness. However, for most transducer configurations, the relationship between frequency response and layer thicknesses is very complicated. To overcome this, we have investigated the stochastic optimisation technique of simulated annealing. This allows a transducer configuration to be obtained with a desired frequency response expressed as a cost function. The cost function reported here maximises uniformity of the fundamental and second and third harmonics of output pressure, which we have achieved to approximately /spl plusmn/3%. The results are promising and may deliver additional bandwidth for applications in underwater sonar and biomedical imaging. To illustrate their potential, we also describe a three-layer 1-3 connectivity piezocomposite transducer with a strong response extending over the fundamental and first two harmonics.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124582803","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192485
H. Masuyama, K. Mizutani, K. Nagai
We present a method for generating a narrow beam such that the direction of radiation is variable using an annular array. A sound source using this method has a clearance between each neighboring element of the array. These clearances are applied to decentring the array elements and the direction of radiated ultrasonic beam becomes controllable. The validity of this method is confirmed with numerical calculations, and it is shown that the beam radiated at a direction of 15 degrees from the perpendicular of the source plane still keeps the sharp profile. The sound source fabricated by this method has small, simple and planar structure, and it suggests the capability of a sound source based on this method developing into various acoustic devices.
{"title":"Sound source with direction-variable beam using annular transducer array","authors":"H. Masuyama, K. Mizutani, K. Nagai","doi":"10.1109/ULTSYM.2002.1192485","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192485","url":null,"abstract":"We present a method for generating a narrow beam such that the direction of radiation is variable using an annular array. A sound source using this method has a clearance between each neighboring element of the array. These clearances are applied to decentring the array elements and the direction of radiated ultrasonic beam becomes controllable. The validity of this method is confirmed with numerical calculations, and it is shown that the beam radiated at a direction of 15 degrees from the perpendicular of the source plane still keeps the sharp profile. The sound source fabricated by this method has small, simple and planar structure, and it suggests the capability of a sound source based on this method developing into various acoustic devices.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114639217","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192611
R. Barkmann, C. Gluer
Quantitative ultrasound (QUS) methods have been shown to be useful in the assessment of bone status. Nevertheless, ultrasound transmission depends on a variety of skeletal parameters, and a detailed understanding of ultrasound propagation through bone is important for the accurate interpretation of QUS results. We determined correlations between morphometrical and QUS parameters at the shaft of human finger phalanges using ultrasound transmission under different angles. 54 phalanges were measured in vitro using QUS and micro computed tomography (/spl mu/-CT). /spl mu/-CT was used for the derivation of geometrical parameters and cortical porosity. Significant and in part independent correlations between QUS and morphometry could be found indicating that QUS methods might be able to estimate different aspects of bone quality.
{"title":"Associations between parameters of ultrasound transmission and structural parameters of cortical bone","authors":"R. Barkmann, C. Gluer","doi":"10.1109/ULTSYM.2002.1192611","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192611","url":null,"abstract":"Quantitative ultrasound (QUS) methods have been shown to be useful in the assessment of bone status. Nevertheless, ultrasound transmission depends on a variety of skeletal parameters, and a detailed understanding of ultrasound propagation through bone is important for the accurate interpretation of QUS results. We determined correlations between morphometrical and QUS parameters at the shaft of human finger phalanges using ultrasound transmission under different angles. 54 phalanges were measured in vitro using QUS and micro computed tomography (/spl mu/-CT). /spl mu/-CT was used for the derivation of geometrical parameters and cortical porosity. Significant and in part independent correlations between QUS and morphometry could be found indicating that QUS methods might be able to estimate different aspects of bone quality.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123587976","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193445
J. Black, R. White, J. Grate
A standing acoustic field excited by an ultrasonic flexural plate wave (FPW) device is shown to trap microspheres and cells suspended in a pressure-driven flowing liquid. Capture is achieved by counteracting the viscous drag forces on a particle with acoustic radiation pressure. The suitability of this technique for biochemical analysis is demonstrated with two experiments: (1) acoustically trapped streptavidin-coated 1 /spl mu/m microspheres conjugated to fluorescent 200 nm biotinylated microspheres; and (2) perfusion of the membrane permeant fluorescein diacetate across acoustically trapped cells. Biochemical interaction was monitored with a fluorescence microscope. Efforts to integrate acoustic traps with on-chip FPW microfluidic pumps are also described.
{"title":"Microsphere capture and perfusion in microchannels using flexural plate wave structures","authors":"J. Black, R. White, J. Grate","doi":"10.1109/ULTSYM.2002.1193445","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193445","url":null,"abstract":"A standing acoustic field excited by an ultrasonic flexural plate wave (FPW) device is shown to trap microspheres and cells suspended in a pressure-driven flowing liquid. Capture is achieved by counteracting the viscous drag forces on a particle with acoustic radiation pressure. The suitability of this technique for biochemical analysis is demonstrated with two experiments: (1) acoustically trapped streptavidin-coated 1 /spl mu/m microspheres conjugated to fluorescent 200 nm biotinylated microspheres; and (2) perfusion of the membrane permeant fluorescein diacetate across acoustically trapped cells. Biochemical interaction was monitored with a fluorescence microscope. Efforts to integrate acoustic traps with on-chip FPW microfluidic pumps are also described.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121988079","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192671
F. Viola, W. Walker
In the breast, prostate and other organs increased tissue stiffness is often associated with the presence of disease. While palpation remains widely used, it has limited sensitivity which is highly dependent upon the skill of the clinician. To overcome this and other limitations a variety of automated approaches have been developed in recent years. These techniques generate tissue deformation by applying acoustic radiation force internally, shear waves superficially, or axial compression. In this paper we propose an alternate approach for elasticity imaging. A shear deformation is applied to the tissue surface. Ultrasound images obtained before and after shear application are processed to yield images of shear strain. We tested this method experimentally on custom acrylamide gel phantoms using a Philips SONOS 5500 imaging system. The phantoms consisted of a 5% acrylamide background with 15% acrylamide inclusions. 50 /spl mu/m sephadex spheres were used in the background and inclusion to introduce ultrasonic scattering. 4% shear rates were generated by translating the upper surface of the 5 cm thick phantoms by 2.0 mm. The shear strains observed within the inclusions of each phantom were roughly one third those seen in the background region. As anticipated, little axial deformation was observed. Experimentally obtained shear strain images clearly delineate the inclusions with few artifacts, although some noise is visible. This noise undoubtedly arises from jitter in the lateral displacement estimates. Theoretical analysis suggests that signal decorrelation under lateral shear will be very small. This, coupled with the minimal artifacts visible in the shear strain images may make shear elastography an attractive alternative to techniques.
在乳腺、前列腺和其他器官中，组织僵硬度的增加通常与疾病的存在有关。虽然触诊仍然广泛使用，但它的灵敏度有限，这高度依赖于临床医生的技能。为了克服这个和其他限制，近年来开发了各种自动化方法。这些技术通过内部施加声辐射力、表面施加剪切波或轴向压缩来产生组织变形。在本文中，我们提出了弹性成像的另一种方法。对组织表面施加剪切变形。对剪切应用前后获得的超声图像进行处理，得到剪切应变图像。我们使用飞利浦SONOS 5500成像系统对定制丙烯酰胺凝胶模型进行了实验测试。幻影由5%丙烯酰胺背景和15%丙烯酰胺内含物组成。采用50 /spl μ m /m的葡聚糖球作为背景和夹杂物，引入超声散射。将5 cm厚的幻影上表面平移2.0 mm，产生4%的剪切速率。在每个幻影的内含物中观察到的剪切应变大约是背景区域中所见的剪切应变的三分之一。正如预期的那样，观察到很少的轴向变形。实验获得的剪切应变图像清晰地描绘了夹杂物，几乎没有伪影，尽管一些噪声是可见的。这种噪声无疑是由侧向位移估计中的抖动引起的。理论分析表明，侧向剪切作用下的信号去相关很小。这一点，加上在剪切应变图像中可见的最小伪影，可能使剪切弹性成像成为一种有吸引力的替代技术。
{"title":"Shear strain elastography","authors":"F. Viola, W. Walker","doi":"10.1109/ULTSYM.2002.1192671","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192671","url":null,"abstract":"In the breast, prostate and other organs increased tissue stiffness is often associated with the presence of disease. While palpation remains widely used, it has limited sensitivity which is highly dependent upon the skill of the clinician. To overcome this and other limitations a variety of automated approaches have been developed in recent years. These techniques generate tissue deformation by applying acoustic radiation force internally, shear waves superficially, or axial compression. In this paper we propose an alternate approach for elasticity imaging. A shear deformation is applied to the tissue surface. Ultrasound images obtained before and after shear application are processed to yield images of shear strain. We tested this method experimentally on custom acrylamide gel phantoms using a Philips SONOS 5500 imaging system. The phantoms consisted of a 5% acrylamide background with 15% acrylamide inclusions. 50 /spl mu/m sephadex spheres were used in the background and inclusion to introduce ultrasonic scattering. 4% shear rates were generated by translating the upper surface of the 5 cm thick phantoms by 2.0 mm. The shear strains observed within the inclusions of each phantom were roughly one third those seen in the background region. As anticipated, little axial deformation was observed. Experimentally obtained shear strain images clearly delineate the inclusions with few artifacts, although some noise is visible. This noise undoubtedly arises from jitter in the lateral displacement estimates. Theoretical analysis suggests that signal decorrelation under lateral shear will be very small. This, coupled with the minimal artifacts visible in the shear strain images may make shear elastography an attractive alternative to techniques.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125840108","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193487
T. Shigematsu, M.K. Kuroswa, K. Asai
A mechanical model of a surface acoustic wave (SAW) motor's stepping motions ranging under 100 nanometers was constructed. The SAW motor had a compliance structure in its movable part to utilize nanometer vibration of SAW for friction drive. The compliance, however, resulted in the two-degree-of-freedom vibration behavior of the movable part. Based on the mechanical model, the system identification was carried out by means of FFT analyses and decay fittings to experimental data. The simulation with the identified model qualitatively represented the experimental results. For more accurate simulations, additional nonlinear effects should be implied to the model.
{"title":"Stepping motion analysis of surface acoustic wave motor toward nanometer resolution positioning system","authors":"T. Shigematsu, M.K. Kuroswa, K. Asai","doi":"10.1109/ULTSYM.2002.1193487","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193487","url":null,"abstract":"A mechanical model of a surface acoustic wave (SAW) motor's stepping motions ranging under 100 nanometers was constructed. The SAW motor had a compliance structure in its movable part to utilize nanometer vibration of SAW for friction drive. The compliance, however, resulted in the two-degree-of-freedom vibration behavior of the movable part. Based on the mechanical model, the system identification was carried out by means of FFT analyses and decay fittings to experimental data. The simulation with the identified model qualitatively represented the experimental results. For more accurate simulations, additional nonlinear effects should be implied to the model.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124647887","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192596
S. Nikolov, J. A. Jensen, R. Dufait, Armin Schoisswohl
Current 3D real-time imaging is done either with sparse 2D arrays, or with mechanically moved phased arrays. The former results in a poor resolution and contrast due to a limited amount of elements. The latter has the disadvantage of low frame rates due to the sequential acquisition of the volume line-by-line and plane-by-plane. This paper describes an approach which combines mechanically moved phased array with synthetic transmit aperture imaging, resulting in high volume acquisition rates without a trade-off in image quality. The scan method uses a conventional fully populated 64 element phased array, which is rotated over the volume of interest. The data is acquired using coded signals and synthetic transmit aperture imaging. Only one group of elements transmits at a time. The delays are set such as to form a cylindrical wave. The back-scattered signal carries information not only from the plane located directly below the transducer, but also from neighboring planes. A complete dataset for all elements for the whole rotation is acquired and stored. The volume is then focused from this complete data set in order to obtain dynamic transmit and receive focusing in all directions.
{"title":"Three-dimensional real-time synthetic aperture imaging using a rotating phased array transducer","authors":"S. Nikolov, J. A. Jensen, R. Dufait, Armin Schoisswohl","doi":"10.1109/ULTSYM.2002.1192596","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192596","url":null,"abstract":"Current 3D real-time imaging is done either with sparse 2D arrays, or with mechanically moved phased arrays. The former results in a poor resolution and contrast due to a limited amount of elements. The latter has the disadvantage of low frame rates due to the sequential acquisition of the volume line-by-line and plane-by-plane. This paper describes an approach which combines mechanically moved phased array with synthetic transmit aperture imaging, resulting in high volume acquisition rates without a trade-off in image quality. The scan method uses a conventional fully populated 64 element phased array, which is rotated over the volume of interest. The data is acquired using coded signals and synthetic transmit aperture imaging. Only one group of elements transmits at a time. The delays are set such as to form a cylindrical wave. The back-scattered signal carries information not only from the plane located directly below the transducer, but also from neighboring planes. A complete dataset for all elements for the whole rotation is acquired and stored. The volume is then focused from this complete data set in order to obtain dynamic transmit and receive focusing in all directions.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125014000","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193541
T. Fujita, K. Toda
A technique for measuring mechanical vibration displacement is proposed using a liquid-delay-line-oscillator, which is composed of two pairs of arch-shaped interdigital transducers (IDTs) on a double-layered substrate composed of a piezoelectric ceramic plate and an acrylic plate, a polymer-film diaphragm as one wall of a liquid cavity, and a water layer. The diaphragm functions as an ultrasound-beam reflector. The acoustical phase change arises corresponding to the pressure exerted on the central part of the diaphragm. The relationship between the mechanical displacement and the oscillation frequency is evaluated experimentally on the basis of the acoustical delay length linearly dependent on the thickness of the water layer. The static and dynamic displacement measurements are demonstrated. The present technique is promising for sensing sound pressure, which could be regarded as a precise and convenient method.
{"title":"A mechanical vibration sensing technique using a liquid delay line oscillator","authors":"T. Fujita, K. Toda","doi":"10.1109/ULTSYM.2002.1193541","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193541","url":null,"abstract":"A technique for measuring mechanical vibration displacement is proposed using a liquid-delay-line-oscillator, which is composed of two pairs of arch-shaped interdigital transducers (IDTs) on a double-layered substrate composed of a piezoelectric ceramic plate and an acrylic plate, a polymer-film diaphragm as one wall of a liquid cavity, and a water layer. The diaphragm functions as an ultrasound-beam reflector. The acoustical phase change arises corresponding to the pressure exerted on the central part of the diaphragm. The relationship between the mechanical displacement and the oscillation frequency is evaluated experimentally on the basis of the acoustical delay length linearly dependent on the thickness of the water layer. The static and dynamic displacement measurements are demonstrated. The present technique is promising for sensing sound pressure, which could be regarded as a precise and convenient method.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128235094","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 : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193351
M. Hofer, N. Finger, G. Kovacs, J. Schoberl, U. Langer, R. Lerch
Though loss parameters in SAW propagation are used as input for fast analysis models for the simulation of SAW devices, the quantitatively correct description of loss mechanisms is still a challenging task. Therefore, it is important to develop exact measurement and simulation methods which are able to determine these loss parameters accurately. By the use of special boundary conditions, the finite element method (FEM) is able to fulfill these requirements. Regarding the periodic substructure of common SAW devices, we have incorporated periodic boundary conditions (PBCs) in our simulation code. The piezoelectric substrate of SAW devices operating at high frequencies can be modeled as a semi-infinite half space. Therefore, we introduce newly evolved absorbing boundary conditions. They allow us to examine effects emerging from bulk acoustic wave (BAW) radiation (e.g. bulk wave onset frequencies) and assess propagation loss due to leakage and bulk wave conversion accurately.
{"title":"Finite element simulation of bulk- and surface acoustic wave (SAW) interaction in SAW devices","authors":"M. Hofer, N. Finger, G. Kovacs, J. Schoberl, U. Langer, R. Lerch","doi":"10.1109/ULTSYM.2002.1193351","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193351","url":null,"abstract":"Though loss parameters in SAW propagation are used as input for fast analysis models for the simulation of SAW devices, the quantitatively correct description of loss mechanisms is still a challenging task. Therefore, it is important to develop exact measurement and simulation methods which are able to determine these loss parameters accurately. By the use of special boundary conditions, the finite element method (FEM) is able to fulfill these requirements. Regarding the periodic substructure of common SAW devices, we have incorporated periodic boundary conditions (PBCs) in our simulation code. The piezoelectric substrate of SAW devices operating at high frequencies can be modeled as a semi-infinite half space. Therefore, we introduce newly evolved absorbing boundary conditions. They allow us to examine effects emerging from bulk acoustic wave (BAW) radiation (e.g. bulk wave onset frequencies) and assess propagation loss due to leakage and bulk wave conversion accurately.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127064018","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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