The Experts below are selected from a list of 2283 Experts worldwide ranked by ideXlab platform
Hugues Duflo - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of an ascending air bubble in a viscous fluid/fiber matrix medium using a Phased Array Transducer
European Journal of Mechanics B-fluids, 2015Co-Authors: Naim Samet, Pierre Marechal, Hugues DufloAbstract:Abstract Detecting porosities of different scales, both micro and macro, is a current problem in the development of composite materials. This is especially true for composite materials manufactured using Resin Transfer Molding (RTM). When injecting resin in the fibrous preform porosities appear, originating essentially because of air trapped in the fiber matrix. Consequently, the interaction between air bubbles and fibers has been the subject of several numerical investigations. In this study, we propose an original experimental method to monitor the interaction of air bubbles with a fibrous matrix. A 10 MHz center frequency ultrasonic Phased Array Transducer is used to monitor air bubbles in the millimeter range. The ultrasonic imaging method is first tested only with bubbles ascending in a channel containing silicone oil. Then it is tested again in a sample of fiber matrix immersed in the same channel. The results prove the effectiveness of the measurement process. These results then can be used to find a correlation between the appearance of porosities and the processes that generate them in order to consider how to improve RTM. They can also be used to understand the interaction phenomena between bubbles and folds in order to improve RTM process.
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monitoring of an ascending air bubble in a viscous fluid fiber matrix medium using a Phased Array Transducer
European Journal of Mechanics B-fluids, 2015Co-Authors: Naim Samet, Pierre Marechal, Hugues DufloAbstract:Abstract Detecting porosities of different scales, both micro and macro, is a current problem in the development of composite materials. This is especially true for composite materials manufactured using Resin Transfer Molding (RTM). When injecting resin in the fibrous preform porosities appear, originating essentially because of air trapped in the fiber matrix. Consequently, the interaction between air bubbles and fibers has been the subject of several numerical investigations. In this study, we propose an original experimental method to monitor the interaction of air bubbles with a fibrous matrix. A 10 MHz center frequency ultrasonic Phased Array Transducer is used to monitor air bubbles in the millimeter range. The ultrasonic imaging method is first tested only with bubbles ascending in a channel containing silicone oil. Then it is tested again in a sample of fiber matrix immersed in the same channel. The results prove the effectiveness of the measurement process. These results then can be used to find a correlation between the appearance of porosities and the processes that generate them in order to consider how to improve RTM. They can also be used to understand the interaction phenomena between bubbles and folds in order to improve RTM process.
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ultrasound monitoring of bubble size and velocity in a fluid model using Phased Array Transducer
Ndt & E International, 2011Co-Authors: Naim Samet, Pierre Marechal, Hugues DufloAbstract:Abstract Experimental studies on composite materials highlighted the existence of gas bubbles (voids) at different scales (micro and macro). These voids, resulting from the fabrication process, are sources of weakness for the end-user material. Therefore, several studies focus on the evaluation and the minimization of void rate. During injection of resin into the fibrous matrix, bubbles appear. Some are dispersed while others persist and diminish the overall quality of the finished product. This study consists in detecting bubbles during the resin transfer molding (RTM) process using an original method based on ultrasound. However, in practice we have to face with several problems due to the heterogeneity of the environment, such as the differentiation of a bubble from a strand or fiber. Due to the complexity of the problem, an experimental setup was built in order to detect bubbles using an ultrasonic Phased Array Transducer in a flow of viscous fluid only, without the presence of fiber matrix. The study deals with the flow of a model fluid, which simulates the injected resin, with presence of air bubbles trapped in a channel production. Since the ultrasonic characteristics of the experimental setup are well known and characterized, the number, velocity and size of air bubbles could be evaluated.
Naim Samet - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of an ascending air bubble in a viscous fluid/fiber matrix medium using a Phased Array Transducer
European Journal of Mechanics B-fluids, 2015Co-Authors: Naim Samet, Pierre Marechal, Hugues DufloAbstract:Abstract Detecting porosities of different scales, both micro and macro, is a current problem in the development of composite materials. This is especially true for composite materials manufactured using Resin Transfer Molding (RTM). When injecting resin in the fibrous preform porosities appear, originating essentially because of air trapped in the fiber matrix. Consequently, the interaction between air bubbles and fibers has been the subject of several numerical investigations. In this study, we propose an original experimental method to monitor the interaction of air bubbles with a fibrous matrix. A 10 MHz center frequency ultrasonic Phased Array Transducer is used to monitor air bubbles in the millimeter range. The ultrasonic imaging method is first tested only with bubbles ascending in a channel containing silicone oil. Then it is tested again in a sample of fiber matrix immersed in the same channel. The results prove the effectiveness of the measurement process. These results then can be used to find a correlation between the appearance of porosities and the processes that generate them in order to consider how to improve RTM. They can also be used to understand the interaction phenomena between bubbles and folds in order to improve RTM process.
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monitoring of an ascending air bubble in a viscous fluid fiber matrix medium using a Phased Array Transducer
European Journal of Mechanics B-fluids, 2015Co-Authors: Naim Samet, Pierre Marechal, Hugues DufloAbstract:Abstract Detecting porosities of different scales, both micro and macro, is a current problem in the development of composite materials. This is especially true for composite materials manufactured using Resin Transfer Molding (RTM). When injecting resin in the fibrous preform porosities appear, originating essentially because of air trapped in the fiber matrix. Consequently, the interaction between air bubbles and fibers has been the subject of several numerical investigations. In this study, we propose an original experimental method to monitor the interaction of air bubbles with a fibrous matrix. A 10 MHz center frequency ultrasonic Phased Array Transducer is used to monitor air bubbles in the millimeter range. The ultrasonic imaging method is first tested only with bubbles ascending in a channel containing silicone oil. Then it is tested again in a sample of fiber matrix immersed in the same channel. The results prove the effectiveness of the measurement process. These results then can be used to find a correlation between the appearance of porosities and the processes that generate them in order to consider how to improve RTM. They can also be used to understand the interaction phenomena between bubbles and folds in order to improve RTM process.
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ultrasound monitoring of bubble size and velocity in a fluid model using Phased Array Transducer
Ndt & E International, 2011Co-Authors: Naim Samet, Pierre Marechal, Hugues DufloAbstract:Abstract Experimental studies on composite materials highlighted the existence of gas bubbles (voids) at different scales (micro and macro). These voids, resulting from the fabrication process, are sources of weakness for the end-user material. Therefore, several studies focus on the evaluation and the minimization of void rate. During injection of resin into the fibrous matrix, bubbles appear. Some are dispersed while others persist and diminish the overall quality of the finished product. This study consists in detecting bubbles during the resin transfer molding (RTM) process using an original method based on ultrasound. However, in practice we have to face with several problems due to the heterogeneity of the environment, such as the differentiation of a bubble from a strand or fiber. Due to the complexity of the problem, an experimental setup was built in order to detect bubbles using an ultrasonic Phased Array Transducer in a flow of viscous fluid only, without the presence of fiber matrix. The study deals with the flow of a model fluid, which simulates the injected resin, with presence of air bubbles trapped in a channel production. Since the ultrasonic characteristics of the experimental setup are well known and characterized, the number, velocity and size of air bubbles could be evaluated.
Jørgen Arendt Jensen - One of the best experts on this subject based on the ideXlab platform.
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Transverse oscillation vector velocity estimation using a Phased Array Transducer
2012 IEEE International Ultrasonics Symposium, 2012Co-Authors: Jønne Marchery, Michael Johannes Pihl, Gert Seerup, Per Haugaard, Svetoslav Ivanov Nikolov, Jørgen Arendt JensenAbstract:The Transverse Oscillation method has shown its commercial feasibility, providing the user with 2D velocity information. Todays implementation on commercial ultrasound platforms only support linear Array Transducers and are limited in depth. Extending the implementation to a Phased Array Transducer, vector velocity echocardiography will become possible. This paper describes the general modification made on the BK Medical 2202 Pro Focus UltraView using a 64 element Phased Array Transducer and the simulations and measurements performed. The results show that velocities can be obtained at depths even greater than 100 mm. Tests at depths of 72 mm and 82 mm with a peak velocity of 0.5 m/s, showed a relative mean bias B̃vx that varied from 0% and to 21% and a relative mean standard deviation σ̃vx that varied from 18% and to 51%. The investigation showed an increasing bias with respect to depth, which leaves room for optimization. Despite the bias, the method has shown to work and produce reliable results, and 2D velocity estimates are provided within the entire color-box down to a depth of more than 100 mm making vector velocity imaging possible in the entire heart.
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Phased-Array vector velocity estimation using transverse oscillations
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2012Co-Authors: Michael Johannes Pihl, Jonne Marcher, Jørgen Arendt JensenAbstract:A method for estimating the 2-D vector velocity of blood using a Phased-Array Transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a Phased-Array geometry and to broaden the potential clinical applicability of the method. A Phased-Array Transducer has a smaller footprint and a larger field of view than a linear Array, and is therefore more suited for, e.g., cardiac imaging. The method relies on suitable TO fields, and a beamforming strategy employing diverging TO beams is proposed. The implementation of the TO method using a Phased-Array Transducer for vector velocity estimation is evaluated through simulation and flow-rig measurements are acquired using an experimental scanner. The vast number of calculations needed to perform flow simulations makes the optimization of the TO fields a cumbersome process. Therefore, three performance metrics are proposed. They are calculated based on the complex TO spectrum of the combined TO fields. It is hypothesized that the performance metrics are related to the performance of the velocity estimates. The simulations show that the squared correlation values range from 0.79 to 0.92, indicating a correlation between the performance metrics of the TO spectrum and the velocity estimates. Because these performance metrics are much more readily computed, the TO fields can be optimized faster for improved velocity estimation of both simulations and measurements. For simulations of a parabolic flow at a depth of 10 cm, a relative (to the peak velocity) bias and standard deviation of 4% and 8%, respectively, are obtained. Overall, the simulations show that the TO method implemented on a Phased-Array Transducer is robust with relative standard deviations around 10% in most cases. The flow-rig measurements show similar results. At a depth of 9.5 cm using 32 emissions per estimate, the relative standard deviation is 9% and the relative bias is -9%. At the center of the vessel, the velocity magnitude is estimated to be 0.25 ± 0.023 m/s, compared with an expected peak velocity magnitude of 0.25 m/s, and the beam-to-flow angle is calculated to be 89.3° ± 0.77°, compared with an expected angle value between 89° and 90°. For steering angles up to ±20° degrees, the relative standard deviation is less than 20%. The results also show that a 64-element Transducer implementation is feasible, but with a poorer performance compared with a 128-element Transducer. The simulation and experimental results demonstrate that the TO method is suitable for use in conjunction with a Phased-Array Transducer, and that 2-D vector velocity estimation is possible down to a depth of 15 cm.
Kirk K. Shung - One of the best experts on this subject based on the ideXlab platform.
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fabrication and characterization of a miniaturized 15 mhz side looking Phased Array Transducer catheter
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2019Co-Authors: Nestor E Cabreramunoz, Chi Tat Chiu, Payam Eliahoo, Jay A. Williams, Robert Wodnicki, Hayong Jung, Qifa Zhou, Guang-zhong Yang, Kirk K. ShungAbstract:This paper describes the development of a miniaturized 15-MHz side-looking Phased-Array Transducer catheter. The Array features a 2–2 linear composite with 64 piezoelectric elements mechanically diced into a piece of PMN-30% PT single crystal and separated by nonconductive epoxy kerfs at a $50-\mu \text{m}$ pitch, yielding a total active aperture of 3.2 mm in the azimuth direction and 1.8 mm in the elevation direction, with an elevation natural focal depth of 8.1 mm. The Array includes nonconductive epoxy backing and two front matching layers. A custom flexible circuit connects the Array piezoelectric elements to a bundle of 64 individual 48-AWG microcoaxial cables enclosed within a 1.5-m-long 10F catheter. Performance characterization was evaluated via finite-element analysis simulations and afterward compared against obtained measurement results, which showed an average center frequency of 17.7 MHz, an average bandwidth of 52.2% at −6 dB, and crosstalk less than −30 dB. The imaging of a tungsten fine-wire phantom resulted in axial and lateral spatial resolutions of approximately 90 and 420 $\mu \text{m}$ , respectively. The imaging capability was further evaluated with colorectal tissue-mimicking phantoms, demonstrating the potential suitability of the proposed Phased-Array Transducer for the intraoperative assessment of surgical margins during minimally invasive colorectal surgery procedures.
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Fabrication and Characterization of a Miniaturized 15-MHz Side-Looking Phased-Array Transducer Catheter
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2019Co-Authors: Nestor E. Cabrera-munoz, Chi Tat Chiu, Payam Eliahoo, Jay A. Williams, Robert Wodnicki, Hayong Jung, Qifa Zhou, Guang-zhong Yang, Kirk K. ShungAbstract:This paper describes the development of a miniaturized 15-MHz side-looking Phased-Array Transducer catheter. The Array features a 2-2 linear composite with 64 piezoelectric elements mechanically diced into a piece of PMN-30% PT single crystal and separated by nonconductive epoxy kerfs at a 50-μm pitch, yielding a total active aperture of 3.2 mm in the azimuth direction and 1.8 mm in the elevation direction, with an elevation natural focal depth of 8.1 mm. The Array includes nonconductive epoxy backing and two front matching layers. A custom flexible circuit connects the Array piezoelectric elements to a bundle of 64 individual 48-AWG microcoaxial cables enclosed within a 1.5-m-long 10F catheter. Performance characterization was evaluated via finite-element analysis simulations and afterward compared against obtained measurement results, which showed an average center frequency of 17.7 MHz, an average bandwidth of 52.2% at -6 dB, and crosstalk less than -30 dB. The imaging of a tungsten finewire phantom resulted in axial and lateral spatial resolutions of approximately 90 and 420 μm, respectively. The imaging capability was further evaluated with colorectal tissue-mimicking phantoms, demonstrating the potential suitability of the proposed Phased-Array Transducer for the intraoperative assessment of surgical margins during minimally invasive colorectal surgery procedures.
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forward looking 30 mhz Phased Array Transducer for peripheral intravascular imaging
Sensors and Actuators A-physical, 2018Co-Authors: Nestor E Cabreramunoz, Chi Tat Chiu, Payam Eliahoo, Jay A. Williams, Robert Wodnicki, Hayong Jung, Qifa Zhou, Kirk K. ShungAbstract:Abstract This paper describes the design, fabrication, and testing of a forward-looking 30-MHz Phased-Array Transducer for peripheral intravascular imaging. The Array features 32 piezoelectric elements arranged in a linear 2-2 composite configuration dry etched into a piece of PMN-30%PT single crystal and separated by non-conductive epoxy kerfs at a 25-μm pitch, yielding a total active aperture of 0.8 mm in the azimuth direction and 1.0 mm in the elevation direction, with an elevation natural focal depth of 5.0 mm. The Array includes non-conductive epoxy backing and two front matching layers. A custom flexible circuit connects the Array piezoelectric elements to a bundle of 32 individual 48-AWG micro-coaxial cables enclosed within a 0.6-m long 8 F catheter. Performance characterization was evaluated via finite element analysis simulations and afterwards compared to measured results, which showed an average center frequency of 28.9 MHz, an average bandwidth of 36.4% at -6 dB, and crosstalk less than -26.5 dB. Imaging of a tungsten fine-wire phantom resulted in axial and lateral spatial resolutions of approximately 65 μm and 215 μm, respectively. The imaging capability was further evaluated with a porcine carotid artery phantom, demonstrating the suitability of the proposed Phased-Array Transducer for peripheral intravascular imaging.
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Fabrication and Characterization of a 20-MHz Microlinear Phased-Array Transducer for Intervention Guidance
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2017Co-Authors: Chi Tat Chiu, Bong Jin Kang, Payam Eliahoo, Theodore Abraham, Kirk K. ShungAbstract:This paper describes the design and fabrication of a miniature ultrasonic Phased-Array Transducer used for intervention guidance. Currently, ultrasound probes are often placed at the body surface of the patients, leading to several drawbacks including the limitation of penetration and image quality. In order to improve the reliability of the guiding process, we propose a miniature Phased-Array Transducer that can be placed adjacent to the intervention device during the interventional procedure. In this paper, we report the work that has been carried out on the development of this miniature Phased-Array Transducer. It comprised 48 elements housed in a 3-mmdiameter needle. A specially designed flexible circuit was used for accommodating the Transducer Array in the long, thin needle housing. The center frequency and the fractional bandwidth were approximately 20 MHz and 42%, respectively, with an average crosstalk lower than -30 dB. The axial and azimuth resolutions were approximately 80 and 210 μm, respectively. The imaging capability of the Transducer was further evaluated by acquiring the B-mode images of a needle in a cow liver. The performance of the proposed Phased-Array Transducer demonstrates the feasibility of such an approach for interventional guidance.
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Fabrication and characterization of a 20 MHz microlinear Phased Array Transducer for intervention guidance
2014 IEEE International Ultrasonics Symposium, 2014Co-Authors: Chi Tat Chiu, Bong Jin Kang, Theodore Abraham, Jay A. Williams, Kirk K. ShungAbstract:This paper describes the design and fabrication of a miniature ultrasonic Phased Array Transducer used for intervention guidance. Interventional procedures such as biopsy have been widely carried out in clinics for both diagnostic and therapeutic purposes of many different kinds of diseases, including cancer and cardiovascular disease. Due to its real-time imaging capability and non-radiating nature, ultrasound has been one of the common guiding tools for interventional procedures. However, currently the ultrasound probes are often placed at the body surface, which leads to several drawbacks including the limitations of image depth and quality. In this work, a miniature Phased Array Transducer that can be placed adjacent to the intervention device has been developed. The Array Transducer comprised 48 elements and was placed in a 4-mm needle housing. The measured average center frequency and the bandwidth were around 18.5 MHz and 61% respectively. The measured axial and lateral image resolutions of the Transducer were 80 μm and 210 μm respectively. The imaging capability of the Transducer was evaluated by acquiring the B-mode images of a needle in a cow liver. The performance of the proposed Phased Array Transducer demonstrates the feasibility of such an approach for interventional guidance.
Sunita Chauhan - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Phased Array Transducers for surgical applications
2007 6th International Conference on Information Communications & Signal Processing, 2007Co-Authors: Qiong Zhang, Jiabin Huang, Sunita ChauhanAbstract:In this paper, we analyze the performance of the circular Phased Array Transducers for surgical applications. A Phased Array Transducer focuses and steers an acoustic beam by manipulating the phase delay of each Transducer electronically. The quality of the intensity distribution of the Phased Array Transducer is assessed primarily by the production of lesion, the intensity in the region proximal to the focal plane, the presence of grating lobes and other secondary maximum. To analyze the performance of Phased Array Transducers, we have developed a computer simulation model to predict the acoustic field intensity in a 3-dimensional space, study the performance of the Phased Array Transducers with different number of elements, elemental radius, medium attenuation, and gap between each element. We have also analyzed and compared the performance of a circular Phased Array and a square Phased Array. From our analysis, we note that a circular Phased Array with 145 elements and 5 mm diameter per element has the most favorable performance in terms of focusing ability and grating lobes.
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High intensity ultrasound Phased Array for surgical applications
2006 International Conference on Biomedical and Pharmaceutical Engineering, 2006Co-Authors: Sunita ChauhanAbstract:In this paper, we present a method for simulating the field intensity of ultrasound beam using a two dimensional Phased Array Transducer for High Intensity Focused Ultrasound (HIFU) based surgery. The parameters used and the field modeling is based on Huygen's principle. We further simulated the field intensity of ultrasound beam in two media, taking into consideration the effect of different attenuation coefficients and beam refraction at the interface. Simulation results show that a focused HIFU beam can be obtained by means of manipulating the phase of the signal in each of the elements in a generic ntimesn-element square Array Transducer.