Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0218
R. Takayama, H. Nakanishi, K. Hashimoto
This paper reviews power durability of SAW filters in terms of its dependence on temperature and input power, and discusses how composition and structure of Al alloy electrodes affect power durability. First, the time to fail (TF) measurement is discussed. It is shown that change of the frequency response must be taken into account for the acceleration test. This is because excess temperature causes shift of the passband. Difference of the chip temperature with the environment must be also considered. Two types of four layer electrodes (AlMgCu/Ti/AlMgCu/Ti and AlScCu/Ti/AlScCu/Ti) are used for the discussion. Series of power durability tests are performed for 800 MHz and 1.9 GHz SAW devices, and we reveal how choice of the additives, their content and layer thicknesses influence behavior of the Al migration and affect the TF performances.
{"title":"Impact of composition and structure of Al alloy electrodes to power durability of SAW devices","authors":"R. Takayama, H. Nakanishi, K. Hashimoto","doi":"10.1109/ULTSYM.2014.0218","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0218","url":null,"abstract":"This paper reviews power durability of SAW filters in terms of its dependence on temperature and input power, and discusses how composition and structure of Al alloy electrodes affect power durability. First, the time to fail (TF) measurement is discussed. It is shown that change of the frequency response must be taken into account for the acceleration test. This is because excess temperature causes shift of the passband. Difference of the chip temperature with the environment must be also considered. Two types of four layer electrodes (AlMgCu/Ti/AlMgCu/Ti and AlScCu/Ti/AlScCu/Ti) are used for the discussion. Series of power durability tests are performed for 800 MHz and 1.9 GHz SAW devices, and we reveal how choice of the additives, their content and layer thicknesses influence behavior of the Al migration and affect the TF performances.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131561433","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0437
Diya Wang, Xuan Yang, J. Wan, Bowen Jing, Lei Zhang, M. Wan
Although ultrasound contrast plane wave imaging can avoid the repeated disruption and capture the transient spatial distribution of microbubbles, it is still limited by lower contrast-to-tissue ratio (CTR) due to low negative peak pressure and lacks of transmit focus. The purpose of this paper was to develop an ultrasound contrast plane wave imaging method combined with pulse inversion bubble wavelet transform imaging (PIWI) technique to improve the CTR of plane wave images. First, a pair of “bubble wavelets” was constructed by microbubbles scattering echoes predicted by modified Herring equation driven by two inverted plane waves. Next, the original echoes from such plane waves were performed by bubble wavelet correlation analysis. Then, such echoes replaced by the maximal wavelet correlation coefficients were summed to distinguish echoes of microbubbles and tissues. In vivo rabbit kidney experiments, the CTR of plane wave imaging was improved to 15.19 dB by PIWI technique without the sacrifice of image frame, which was larger 4.48±0.96 dB than that of raw images. In summary, this method could contribute to plane wave imaging by allowing the continuous transient monitoring of the accumulation of microbubbles with higher CTR.
{"title":"Ultrasound contrast plane wave imaging with higher CTR based on pulse inversion bubble wavelet transform","authors":"Diya Wang, Xuan Yang, J. Wan, Bowen Jing, Lei Zhang, M. Wan","doi":"10.1109/ULTSYM.2014.0437","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0437","url":null,"abstract":"Although ultrasound contrast plane wave imaging can avoid the repeated disruption and capture the transient spatial distribution of microbubbles, it is still limited by lower contrast-to-tissue ratio (CTR) due to low negative peak pressure and lacks of transmit focus. The purpose of this paper was to develop an ultrasound contrast plane wave imaging method combined with pulse inversion bubble wavelet transform imaging (PIWI) technique to improve the CTR of plane wave images. First, a pair of “bubble wavelets” was constructed by microbubbles scattering echoes predicted by modified Herring equation driven by two inverted plane waves. Next, the original echoes from such plane waves were performed by bubble wavelet correlation analysis. Then, such echoes replaced by the maximal wavelet correlation coefficients were summed to distinguish echoes of microbubbles and tissues. In vivo rabbit kidney experiments, the CTR of plane wave imaging was improved to 15.19 dB by PIWI technique without the sacrifice of image frame, which was larger 4.48±0.96 dB than that of raw images. In summary, this method could contribute to plane wave imaging by allowing the continuous transient monitoring of the accumulation of microbubbles with higher CTR.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127576095","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0505
S. Doberstein
This paper presents the new balanced SAW filters using fan-shaped IDTs with reduced insertion loss, a fractional bandwidth of 10-24% on 128°YX LiNbO3. The fan-shaped three-transducer structure containing one input IDT and two output IDTs with the split electrodes is used in these filters. The constructional and topological optimization of the SAW filters is provided with a computer simulation using an δ-function model. The 255, 305 MHz samples of the SAW filters have shown 3-dB bandwidth of 30-61 MHz, insertion loss of 5.5-7.5 dB, passband ripple of around 3 dB, shape factor of 1.28-1.5, stopband attenuation over 40 dB in a matched system. The samples were housed in the 5×5×1.35 mm SMD packages and could operate in balanced/unbalanced 50-Ω system.
本文介绍了采用扇形idt的新型平衡SAW滤波器，在128°YX LiNbO3上降低了插入损耗，分数带宽为10-24%。这些滤波器采用扇形三换能器结构，其中包含一个输入IDT和两个带分裂电极的输出IDT。利用δ函数模型对声表面波滤波器的结构和拓扑进行了计算机仿真。在255、305 MHz采样下，SAW滤波器的3-dB带宽为30-61 MHz，插入损耗为5.5-7.5 dB，通带纹波约为3 dB，形状因子为1.28-1.5，阻带衰减超过40 dB。样品被安置在5×5×1.35 mm SMD封装中，可以在平衡/不平衡50-Ω系统中运行。
{"title":"Balanced wide band fan-shaped three-tranducer SAW filters with reduced insertion loss and improved frequency response","authors":"S. Doberstein","doi":"10.1109/ULTSYM.2014.0505","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0505","url":null,"abstract":"This paper presents the new balanced SAW filters using fan-shaped IDTs with reduced insertion loss, a fractional bandwidth of 10-24% on 128°YX LiNbO3. The fan-shaped three-transducer structure containing one input IDT and two output IDTs with the split electrodes is used in these filters. The constructional and topological optimization of the SAW filters is provided with a computer simulation using an δ-function model. The 255, 305 MHz samples of the SAW filters have shown 3-dB bandwidth of 30-61 MHz, insertion loss of 5.5-7.5 dB, passband ripple of around 3 dB, shape factor of 1.28-1.5, stopband attenuation over 40 dB in a matched system. The samples were housed in the 5×5×1.35 mm SMD packages and could operate in balanced/unbalanced 50-Ω system.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"556 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133633516","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0109
S. Harput, J. Mclaughlan, D. Cowell, S. Freear
In medical ultrasound, B-mode images are log-compressed and displayed with a grayscale map, typically on a 40-60 dB dynamic range. The image formation process is the same for an ultrasound pulse compression system using coded excitation. Metrics, such as full width at half maximum (FWHM), peak sidelobe level (PSL) and integrated sidelobe level (ISL), used to evaluate pulse compression systems were adopted from radar and communications. These metrics are utilized to evaluate the performance of an auto-correlation function, which is the ideal case. In medical ultrasound imaging however, the combination of frequency and depth dependent attenuation, dispersion, harmonic generation, beamforming errors, and limited transducer bandwidth create a more complicated case for a pulse compressed system that is far from the ideal.
{"title":"New performance metrics for ultrasound pulse compression systems","authors":"S. Harput, J. Mclaughlan, D. Cowell, S. Freear","doi":"10.1109/ULTSYM.2014.0109","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0109","url":null,"abstract":"In medical ultrasound, B-mode images are log-compressed and displayed with a grayscale map, typically on a 40-60 dB dynamic range. The image formation process is the same for an ultrasound pulse compression system using coded excitation. Metrics, such as full width at half maximum (FWHM), peak sidelobe level (PSL) and integrated sidelobe level (ISL), used to evaluate pulse compression systems were adopted from radar and communications. These metrics are utilized to evaluate the performance of an auto-correlation function, which is the ideal case. In medical ultrasound imaging however, the combination of frequency and depth dependent attenuation, dispersion, harmonic generation, beamforming errors, and limited transducer bandwidth create a more complicated case for a pulse compressed system that is far from the ideal.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133639161","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0490
Jing Cui, Jianke Du, Ji Wang
An analytical approach is taken to investigate SH wave propagation in a layered viscoelastic/piezoelectric structure loaded with nonconductive liquid. The interface between the viscoelastic layer and the piezoelectric substrate is perfect. The dispersion relations are obtained for electrically shorted and open case, respectively. The effects of the dynamic viscous coefficient of the liquid on the phase velocity and the attenuation are figured and presented.
{"title":"Effects of viscous liquid on SH wave propagation in layered viscoelastic/piezoelectric structure","authors":"Jing Cui, Jianke Du, Ji Wang","doi":"10.1109/ULTSYM.2014.0490","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0490","url":null,"abstract":"An analytical approach is taken to investigate SH wave propagation in a layered viscoelastic/piezoelectric structure loaded with nonconductive liquid. The interface between the viscoelastic layer and the piezoelectric substrate is perfect. The dispersion relations are obtained for electrically shorted and open case, respectively. The effects of the dynamic viscous coefficient of the liquid on the phase velocity and the attenuation are figured and presented.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134027819","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0136
Andreas Schroder, B. Henning
Code division multiple access is a well-known method to minimize crosstalk between unsynchronized ultrasonic distance sensors. Thereby orthogonal signals are used which are generated by modulating orthogonal codes to a carrier signal. In this contribution PSK modulation is used to transmit gold sequences. Here narrow band air ultrasound transducers are used. Due to the limited bandwidth of the transducer there is a partial cross correlation between the electrical received signals. This can increase the error rate identifying the signals. By optimizing the modulation parameters the error rate can be reduced. Therefore the influence of an offset of the carrier frequency for different symbol lengths to the properties of the electrical received signals is investigated.
{"title":"Signal optimization of PSK modulated gold-sequences for narrow band transducers","authors":"Andreas Schroder, B. Henning","doi":"10.1109/ULTSYM.2014.0136","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0136","url":null,"abstract":"Code division multiple access is a well-known method to minimize crosstalk between unsynchronized ultrasonic distance sensors. Thereby orthogonal signals are used which are generated by modulating orthogonal codes to a carrier signal. In this contribution PSK modulation is used to transmit gold sequences. Here narrow band air ultrasound transducers are used. Due to the limited bandwidth of the transducer there is a partial cross correlation between the electrical received signals. This can increase the error rate identifying the signals. By optimizing the modulation parameters the error rate can be reduced. Therefore the influence of an offset of the carrier frequency for different symbol lengths to the properties of the electrical received signals is investigated.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134049192","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0545
B. Diarra, M. Robini, Emmanuel Roux, H. Liebgott, C. Cachard, P. Tortoli
The non-grid sparse array technique is a promising approach to overcome the connection difficulties of 2D matrix arrays and to partially compensate the energy loss linked to the element number reduction. Being independent from the spatial sampling conditions, this method leads to a significant improvement of the beam pattern when combined to the simulated annealing algorithm. However, in the previous version of this method, the position of the elements cannot be changed during the optimization. In order to add a further degree of freedom and thus to improve the optimization performance, we propose a new strategy in which both element position and apodization can be modified. This new approach improves the sensitivity thanks to a better distribution of the elements on the array footprint.
{"title":"Optimization of free-moving elements in 2D ultrasound sparse arrays","authors":"B. Diarra, M. Robini, Emmanuel Roux, H. Liebgott, C. Cachard, P. Tortoli","doi":"10.1109/ULTSYM.2014.0545","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0545","url":null,"abstract":"The non-grid sparse array technique is a promising approach to overcome the connection difficulties of 2D matrix arrays and to partially compensate the energy loss linked to the element number reduction. Being independent from the spatial sampling conditions, this method leads to a significant improvement of the beam pattern when combined to the simulated annealing algorithm. However, in the previous version of this method, the position of the elements cannot be changed during the optimization. In order to add a further degree of freedom and thus to improve the optimization performance, we propose a new strategy in which both element position and apodization can be modified. This new approach improves the sensitivity thanks to a better distribution of the elements on the array footprint.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131934226","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0315
Chien-Hao Chiu, Meng-Lin Li
To avoid large grating lobes, using a small element-to-element pitch of ultrasound array transducers for photoacoustic (PA) imaging is necessary. Such constraint introduces higher system cost and complexity, especially when greater than 20-MHz high-frequency arrays are used. As a result, to reduce fabrication difficulties and obtain better signal sensitivity in PA imaging, ultrasound linear array transducers are commonly used in practice instead of phased arrays. However, the field-of-view (FOV) is limited to the full aperture size because linear arrays do not have the ability to steer PA receive beams without the introduction of large grating lobes. In addition, strong PA signals are commonly generated in the near field in the back-ward mode where grating-lobe clutters can even hamper the image contrast seriously. In this study, we proposed a novel compressed-sensing-like grating-lobe suppressed image reconstruction method for PA linear array imaging. To overcome the tradeoff between FOV and grating lobe clutters introduced by using a linear array, compressive sensing (CS) concept is adopted here to reduce the grating lobes. The CS theory relies on an important principle: sparsity. Fortunately, unlike ultrasound imaging, absorption distribution in PA imaging intrinsically owns sparsity in the spatial domain. In consequence, a sparsity constraint minimizing the L1 norm of energy deposition can be introduced to the conventional reconstruction method. By adopting such a constraint and using the nonlinear recovery algorithm based on convex optimization, PA linear array imaging can be reconstructed with grating lobe clutters greatly suppressed. Simulation results demonstrated that the proposed method can reduce the grating lobes caused by using a linear array with large FOV. In the meantime, compared with the image reconstructed by the traditional back-projection method, the image reconstructed by the proposed method has fewer artifacts.
{"title":"Compressive-sensing like grating-lobe suppressed image reconstruction for photoacoustic linear array imaging","authors":"Chien-Hao Chiu, Meng-Lin Li","doi":"10.1109/ULTSYM.2014.0315","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0315","url":null,"abstract":"To avoid large grating lobes, using a small element-to-element pitch of ultrasound array transducers for photoacoustic (PA) imaging is necessary. Such constraint introduces higher system cost and complexity, especially when greater than 20-MHz high-frequency arrays are used. As a result, to reduce fabrication difficulties and obtain better signal sensitivity in PA imaging, ultrasound linear array transducers are commonly used in practice instead of phased arrays. However, the field-of-view (FOV) is limited to the full aperture size because linear arrays do not have the ability to steer PA receive beams without the introduction of large grating lobes. In addition, strong PA signals are commonly generated in the near field in the back-ward mode where grating-lobe clutters can even hamper the image contrast seriously. In this study, we proposed a novel compressed-sensing-like grating-lobe suppressed image reconstruction method for PA linear array imaging. To overcome the tradeoff between FOV and grating lobe clutters introduced by using a linear array, compressive sensing (CS) concept is adopted here to reduce the grating lobes. The CS theory relies on an important principle: sparsity. Fortunately, unlike ultrasound imaging, absorption distribution in PA imaging intrinsically owns sparsity in the spatial domain. In consequence, a sparsity constraint minimizing the L1 norm of energy deposition can be introduced to the conventional reconstruction method. By adopting such a constraint and using the nonlinear recovery algorithm based on convex optimization, PA linear array imaging can be reconstructed with grating lobe clutters greatly suppressed. Simulation results demonstrated that the proposed method can reduce the grating lobes caused by using a linear array with large FOV. In the meantime, compared with the image reconstructed by the traditional back-projection method, the image reconstructed by the proposed method has fewer artifacts.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133024951","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0512
A. Darinskii, M. Weihnacht, H. Schmidt
The harmonic surface acoustic wave (SAW) scattering at 90-degree corners of piezoelectric substrates is studied by FEM. The SAW is incident perpendicular to the vertical border. The dependences of the reflection and transmission coefficients on the radius of the fillet at the corner are found for 128°YX and YZ LiNbO3 as well as ST-X quartz substrates. It is demonstrated that if the substrate is anisotropic, then a SAW can be scattered off differently at the right-hand border and the left-hand border. Computations for YZ LiNbO3 illustrate possible levels of the anisotropy of the scattering for mutually reverse directions of incidence. However, if the substrate is oriented in a specific manner, then the scattering from the right-hand border is identical to the scattering from the left-hand border. There are four types of such orientations.
{"title":"Surface acoustic wave scattering by substrate edges","authors":"A. Darinskii, M. Weihnacht, H. Schmidt","doi":"10.1109/ULTSYM.2014.0512","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0512","url":null,"abstract":"The harmonic surface acoustic wave (SAW) scattering at 90-degree corners of piezoelectric substrates is studied by FEM. The SAW is incident perpendicular to the vertical border. The dependences of the reflection and transmission coefficients on the radius of the fillet at the corner are found for 128°YX and YZ LiNbO3 as well as ST-X quartz substrates. It is demonstrated that if the substrate is anisotropic, then a SAW can be scattered off differently at the right-hand border and the left-hand border. Computations for YZ LiNbO3 illustrate possible levels of the anisotropy of the scattering for mutually reverse directions of incidence. However, if the substrate is oriented in a specific manner, then the scattering from the right-hand border is identical to the scattering from the left-hand border. There are four types of such orientations.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"519 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134090291","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 : 2014-10-23DOI: 10.1109/ULTSYM.2014.0319
Tae-Hoon Bok, E. Hysi, Michael C. Kolios
In this paper, high-frequency photoacoustic (PA) imaging is proposed to simultaneously measure erythrocyte aggregation (EA) and oxygen saturation (SO2). EA is a reversible phenomenon where red blood cells aggregate under flowing conditions and it becomes pathological when enhanced in a number of circulatory disorders. Here we investigate the feasibility of PA imaging in detecting EA-induced changes in SO2 in a simulated circulatory flow system. For all optical wavelengths of illumination (750 and 850 nm), the mean PA amplitude inside the region of interest cyclically varied at intervals corresponding to the beat rate (30, 60, and 90 bpm). The vessel diameter also cyclically varied at the same time interval, but the phase of its variation was reversed compared to the PA amplitude variations. This was expected: as the blood velocity decreased, the shear rate in the radial direction also decreased, resulting in increased EA thus enhancing the PA amplitude due to the increased effective absorber size. When the velocity is increased, the aforementioned process is reversed, resulting in decreased EA and PA amplitude. The cyclic variation in SO2 was evident for the highest beat rate, and differences in the mean PA amplitude at 750 and 850 nm were detected for all beat rates. This indicates that the SO2 was varying while blood was flowing with the different beat rates. The temporal variation in SO2 can be correlated to EA, since it has been reported that oxygen release is inhibited by EA.
{"title":"Simultaneous measurement of erythrocyte aggregarion and oxygen saturation under in vitro pulsatile blood flow by high-frequency photoacoustics","authors":"Tae-Hoon Bok, E. Hysi, Michael C. Kolios","doi":"10.1109/ULTSYM.2014.0319","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0319","url":null,"abstract":"In this paper, high-frequency photoacoustic (PA) imaging is proposed to simultaneously measure erythrocyte aggregation (EA) and oxygen saturation (SO2). EA is a reversible phenomenon where red blood cells aggregate under flowing conditions and it becomes pathological when enhanced in a number of circulatory disorders. Here we investigate the feasibility of PA imaging in detecting EA-induced changes in SO2 in a simulated circulatory flow system. For all optical wavelengths of illumination (750 and 850 nm), the mean PA amplitude inside the region of interest cyclically varied at intervals corresponding to the beat rate (30, 60, and 90 bpm). The vessel diameter also cyclically varied at the same time interval, but the phase of its variation was reversed compared to the PA amplitude variations. This was expected: as the blood velocity decreased, the shear rate in the radial direction also decreased, resulting in increased EA thus enhancing the PA amplitude due to the increased effective absorber size. When the velocity is increased, the aforementioned process is reversed, resulting in decreased EA and PA amplitude. The cyclic variation in SO2 was evident for the highest beat rate, and differences in the mean PA amplitude at 750 and 850 nm were detected for all beat rates. This indicates that the SO2 was varying while blood was flowing with the different beat rates. The temporal variation in SO2 can be correlated to EA, since it has been reported that oxygen release is inhibited by EA.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125674140","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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