Pub Date : 2024-06-12DOI: 10.1109/OJUFFC.2024.3413603
Tony Merrien;Pierre Didier;Emmanuelle Algré
In this paper, a linear lumped-element equivalent circuit model (ECM) for ultrasonic laterally transduced electrostatic bulk-mode air-coupled resonant micro-electro-mechanical systems (MEMS) is described. A single-crystal silicon (SCS) square plate with T-shaped tethers is considered as the geometry of interest with a one-sided electrostatic actuation. This type of sensor can be used for sensitive mass sensing of airborne particles and possesses a large active surface with in-plane vibration modes in the ultrasonic frequency range. Firstly, the eigensolutions and eigenvectors of the problem are obtained using analytical equations and compared with finite-element modeling (FEM) solutions. Secondly, using modal analysis, the number of degrees of freedom is reduced and individual solutions are provided for each vibration mode, leading to various effective masses, stiffnesses and dampings. The first order Taylor expansion of both the electrical current equation and the electrostatic force applied on the resonator allows one to obtain expressions for the additional stiffness and the electro-mechanical transformation coefficient linked to the membrane actuation. Based on theses results, single-input single output (SISO) equivalent circuits are established using electro-mechanical and Butterworth-Van Dyke (BVD) approaches. Electrical admittance simulations resulting from different in-plane vibration modes are proven to be in excellent agreement with FEM simulations. Finally, a numerical mass sensing application is described to evaluate the relevance of both the model and the resonator design to act as a microbalance. The proposed model can be used to design, predict, analyze and optimize the behavior of highly sensitive air-coupled ultrasonic bulk-mode SCS MEMS for various physical applications.
本文描述了超声横向传导静电体模空气耦合谐振微机电系统（MEMS）的线性叠加元件等效电路模型（ECM）。单晶硅 (SCS) 方板与 T 形拴绳被视为具有单面静电驱动的相关几何形状。这种传感器可用于空气颗粒的灵敏质量传感，并具有较大的活动表面，在超声波频率范围内具有面内振动模式。首先，利用分析方程获得了问题的特征解和特征向量，并与有限元建模（FEM）解进行了比较。其次，通过模态分析，减少了自由度的数量，并为每种振动模式提供了单独的解决方案，从而得出各种有效质量、刚度和阻尼。通过对施加在谐振器上的电流方程和静电力进行一阶泰勒展开，可以获得与膜致动相关的附加刚度和电动机械转换系数的表达式。根据这些结果，利用电子机械和巴特沃斯-范戴克（BVD）方法建立了单输入单输出（SISO）等效电路。不同面内振动模式产生的电导纳模拟结果与有限元模拟结果非常吻合。最后，描述了一个数值质量传感应用，以评估模型和谐振器设计作为微天平的相关性。所提出的模型可用于设计、预测、分析和优化高灵敏度空气耦合超声波体模 SCS MEMS 的行为，适用于各种物理应用。
{"title":"Equivalent Circuit Modeling of Air-Coupled Laterally Actuated Electrostatic Bulk-Mode MEMS","authors":"Tony Merrien;Pierre Didier;Emmanuelle Algré","doi":"10.1109/OJUFFC.2024.3413603","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3413603","url":null,"abstract":"In this paper, a linear lumped-element equivalent circuit model (ECM) for ultrasonic laterally transduced electrostatic bulk-mode air-coupled resonant micro-electro-mechanical systems (MEMS) is described. A single-crystal silicon (SCS) square plate with T-shaped tethers is considered as the geometry of interest with a one-sided electrostatic actuation. This type of sensor can be used for sensitive mass sensing of airborne particles and possesses a large active surface with in-plane vibration modes in the ultrasonic frequency range. Firstly, the eigensolutions and eigenvectors of the problem are obtained using analytical equations and compared with finite-element modeling (FEM) solutions. Secondly, using modal analysis, the number of degrees of freedom is reduced and individual solutions are provided for each vibration mode, leading to various effective masses, stiffnesses and dampings. The first order Taylor expansion of both the electrical current equation and the electrostatic force applied on the resonator allows one to obtain expressions for the additional stiffness and the electro-mechanical transformation coefficient linked to the membrane actuation. Based on theses results, single-input single output (SISO) equivalent circuits are established using electro-mechanical and Butterworth-Van Dyke (BVD) approaches. Electrical admittance simulations resulting from different in-plane vibration modes are proven to be in excellent agreement with FEM simulations. Finally, a numerical mass sensing application is described to evaluate the relevance of both the model and the resonator design to act as a microbalance. The proposed model can be used to design, predict, analyze and optimize the behavior of highly sensitive air-coupled ultrasonic bulk-mode SCS MEMS for various physical applications.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"63-76"},"PeriodicalIF":0.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10555284","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141439401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-10DOI: 10.1109/OJUFFC.2024.3411578
Anders Emil Vrålstad;Ole Marius Hoel Rindal;Tore Grüner Bjåstad;Svein-Erik Måsøy
In beamforming, retrospective change in sound speed and recalculation of focusing delays is attractive both for improving image quality and for using it in an iterative image quality optimization process. Modifying the speed of sound retrospectively for focused transmits is challenging because the transmit focus position is a function of sound speed error. The virtual source model is a common way to calculate the transmit focusing delays where using the correct transmit focus position is imperative. In this paper, we provide the methods necessary to perform a retrospective sound-speed correction by compensating the receive grid and by calculating the effective transmit focus needed to perform proper synthetic transmit focusing. To evaluate the efficacy of our method, we simulate wave propagation and measure the resolution of in vitro images using both phased and curvilinear arrays. The results of the suggested virtual source estimation method match the simulated wave propagation for multiple F-numbers and both positive and negative sound speed errors. We compare beamformed images using correct/incorrect sound speeds and correct/incorrect virtual source positions. The results demonstrate that the Corrected Virtual Source (CVS) method generates artifact-free images with superior quality compared to images with incorrect sound speed. Furthermore, the image beamformed with the correct sound speed, but incorrect virtual source position, exhibits image artifacts and inferior focusing quality compared to the CVS image.
在波束成形中，追溯性地改变声速和重新计算聚焦延迟对提高图像质量和在迭代图像质量优化过程中使用都很有吸引力。由于发射聚焦位置是声速误差的函数，因此追溯性地修改聚焦发射的声速具有挑战性。虚拟声源模型是计算发射聚焦延迟的常用方法，在这种情况下，必须使用正确的发射聚焦位置。在本文中，我们提供了通过补偿接收网格和计算正确合成发射聚焦所需的有效发射聚焦来进行声速回溯校正的必要方法。为了评估我们方法的有效性，我们模拟了波的传播，并使用相位阵列和曲线阵列测量了体外图像的分辨率。所建议的虚拟声源估算方法的结果与模拟的多 F 数和正负声速误差的波传播相吻合。我们比较了使用正确/不正确声速和正确/不正确虚拟声源位置的波束形成图像。结果表明，与声速错误的图像相比，校正虚拟声源（CVS）方法生成的无伪影图像质量更高。此外，与 CVS 图像相比，采用正确声速但虚拟声源位置不正确的波束成形图像会出现图像伪影，聚焦质量较差。
{"title":"Sound Speed and Virtual Source Correction in Synthetic Transmit Focusing","authors":"Anders Emil Vrålstad;Ole Marius Hoel Rindal;Tore Grüner Bjåstad;Svein-Erik Måsøy","doi":"10.1109/OJUFFC.2024.3411578","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3411578","url":null,"abstract":"In beamforming, retrospective change in sound speed and recalculation of focusing delays is attractive both for improving image quality and for using it in an iterative image quality optimization process. Modifying the speed of sound retrospectively for focused transmits is challenging because the transmit focus position is a function of sound speed error. The virtual source model is a common way to calculate the transmit focusing delays where using the correct transmit focus position is imperative. In this paper, we provide the methods necessary to perform a retrospective sound-speed correction by compensating the receive grid and by calculating the effective transmit focus needed to perform proper synthetic transmit focusing. To evaluate the efficacy of our method, we simulate wave propagation and measure the resolution of in vitro images using both phased and curvilinear arrays. The results of the suggested virtual source estimation method match the simulated wave propagation for multiple F-numbers and both positive and negative sound speed errors. We compare beamformed images using correct/incorrect sound speeds and correct/incorrect virtual source positions. The results demonstrate that the Corrected Virtual Source (CVS) method generates artifact-free images with superior quality compared to images with incorrect sound speed. Furthermore, the image beamformed with the correct sound speed, but incorrect virtual source position, exhibits image artifacts and inferior focusing quality compared to the CVS image.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"52-62"},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10552357","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sandwich panels, composed of two steel faces and a rigid foam core, are an inexpensive and lightweight option for construction industry. However, voids can form in the foam core during the manufacturing process. This paper uses ultrasonic testing to detect such voids in the foam core of sandwich panels, buried a few millimeters below the surface. The testing setup employs both air-coupled and non-contact ultrasonic testing. Different frequencies are investigated for their influence on the detection capabilities. Two air-coupled experimental setups are constructed, one at 40kHz and the other one at 200kHz. Artificial defects are carved into the sandwich panel at different depths. The results are compared to a simulation. We found that detecting buried voids in these sandwich panels is feasible. The 40-kHz setup has a larger penetration depth of 14mm, while the 200-kHz setup has a smaller penetration depth of 2.5mm. The 200-kHz setup shows a better contrast, i.e. the amplitude at the defect increases by 27% compared to 6% with the 40-kHz setup. These methods enable air-coupled, non-contact ultrasonic testing of buried defects in sandwich panels. They have the potential to be integrated into production lines, contributing to improved material efficiency and quality control for these sandwich panels.
{"title":"Air-Coupled Lamb Wave Testing of Buried Air-Voids in Foam-Filled Sandwich Panels","authors":"Christoph Haugwitz;Andre Reinartz;Jan-Helge Dörsam;Sonja Wismath;Gianni Allevato;Jan Hinrichs;Paulina Gorol;Annalena Kühn;Thomas Hahn-Jose;Jörg Lange;Mario Kupnik","doi":"10.1109/OJUFFC.2024.3410169","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3410169","url":null,"abstract":"Sandwich panels, composed of two steel faces and a rigid foam core, are an inexpensive and lightweight option for construction industry. However, voids can form in the foam core during the manufacturing process. This paper uses ultrasonic testing to detect such voids in the foam core of sandwich panels, buried a few millimeters below the surface. The testing setup employs both air-coupled and non-contact ultrasonic testing. Different frequencies are investigated for their influence on the detection capabilities. Two air-coupled experimental setups are constructed, one at 40kHz and the other one at 200kHz. Artificial defects are carved into the sandwich panel at different depths. The results are compared to a simulation. We found that detecting buried voids in these sandwich panels is feasible. The 40-kHz setup has a larger penetration depth of 14mm, while the 200-kHz setup has a smaller penetration depth of 2.5mm. The 200-kHz setup shows a better contrast, i.e. the amplitude at the defect increases by 27% compared to 6% with the 40-kHz setup. These methods enable air-coupled, non-contact ultrasonic testing of buried defects in sandwich panels. They have the potential to be integrated into production lines, contributing to improved material efficiency and quality control for these sandwich panels.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"150-159"},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10549941","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes a new 3D spatial sensing approach via compressed sensing (CS) by using a single-channel air-coupled piezoelectric micromachined ultrasonic transducer (PMUT) operated with multi-frequency. Our study focuses on a single-channel transducer with a PMUT array composed of several diaphragms with different radius sizes. It is known that small variations in the radius size can cause distinct transmission signals of all diaphragms that are excited by the same excitation signal. In this way, the acoustic field distribution of a region of interest (ROI) can be distorted especially in the direction perpendicular to the wave propagation, which could help to obtain more distinctive information about the scatterers at different locations in any 3D ROI. Therefore, a compressed 3D spatial sensing approach is proposed and used for acquiring measurements of the designed single-channel transducer. The information of any object in a 3D ROI can be mapped onto a collection of basis functions constructed via the nearly mutual orthogonal echo signals from all scatterers in the ROI. Furthermore, the proposed approach is verified with simulated acoustic measurements obtained from the established PMUT equivalent circuit model and the K-Wave acoustic propagation model via an obstacle-sensing application. Based on the sparsity nature of objects in the ROI, the reconstruction of 2D/3D images of objects can be accomplished via a CS-based algorithm. The obtained image reconstruction results show that the proposed approach allows not only for detecting localization but also for reconstructing descriptive features of an object.
本文提出了一种新的三维空间传感方法，即使用单通道空气耦合压电微机械超声换能器（PMUT）进行多频压缩传感（CS）。我们的研究侧重于单通道换能器，其 PMUT 阵列由多个半径不同的膜片组成。众所周知，半径大小的微小变化会导致被同一激励信号激发的所有膜片产生不同的传输信号。这样，感兴趣区域（ROI）的声场分布就会失真，特别是在垂直于波传播的方向上，这有助于获得有关任何三维 ROI 中不同位置散射体的更多独特信息。因此，我们提出了一种压缩三维空间传感方法，并将其用于获取所设计的单通道传感器的测量结果。三维 ROI 中任何物体的信息都可以映射到通过来自 ROI 中所有散射体的几乎相互正交的回波信号构建的基函数集合上。此外，通过障碍物感应应用，利用已建立的 PMUT 等效电路模型和 K 波声传播模型获得的模拟声学测量结果，对所提出的方法进行了验证。基于 ROI 中物体的稀疏性，可以通过基于 CS 的算法重建物体的 2D/3D 图像。获得的图像重建结果表明，所提出的方法不仅能检测定位，还能重建物体的描述性特征。
{"title":"Theoretical Validation of a Single-Channel Air-Coupled PMUT With Multi-Frequency Operation for Compressed 3D Spatial Sensing","authors":"Tingzhong Xu;Zhongjie Zhang;Rodrigo Tumolin Rocha;Liang Zeng;Chunlei Xu","doi":"10.1109/OJUFFC.2024.3408138","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3408138","url":null,"abstract":"This paper proposes a new 3D spatial sensing approach via compressed sensing (CS) by using a single-channel air-coupled piezoelectric micromachined ultrasonic transducer (PMUT) operated with multi-frequency. Our study focuses on a single-channel transducer with a PMUT array composed of several diaphragms with different radius sizes. It is known that small variations in the radius size can cause distinct transmission signals of all diaphragms that are excited by the same excitation signal. In this way, the acoustic field distribution of a region of interest (ROI) can be distorted especially in the direction perpendicular to the wave propagation, which could help to obtain more distinctive information about the scatterers at different locations in any 3D ROI. Therefore, a compressed 3D spatial sensing approach is proposed and used for acquiring measurements of the designed single-channel transducer. The information of any object in a 3D ROI can be mapped onto a collection of basis functions constructed via the nearly mutual orthogonal echo signals from all scatterers in the ROI. Furthermore, the proposed approach is verified with simulated acoustic measurements obtained from the established PMUT equivalent circuit model and the K-Wave acoustic propagation model via an obstacle-sensing application. Based on the sparsity nature of objects in the ROI, the reconstruction of 2D/3D images of objects can be accomplished via a CS-based algorithm. The obtained image reconstruction results show that the proposed approach allows not only for detecting localization but also for reconstructing descriptive features of an object.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"37-51"},"PeriodicalIF":0.0,"publicationDate":"2024-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10545345","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141333959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1109/OJUFFC.2024.3398595
Anders Emil Vrålstad;Magnus Dalen Kvalevåg;Ole Marius Hoel Rindal;Svein-Erik Måsøy
REFoCUS (Retrospective Encoding For Conventional Ultrasound Sequences) offers great flexibility by enabling synthetic aperture beamforming from conventional ultrasound sequences. This flexibility is beneficial for many aspects in medical ultrasound beamforming, including e.g. combination of different transmit waves, distributed sound speed estimation and common-midpoint gathers. REFoCUS beamforming also has image quality comparable to state-of-art methods such as Retrospective Transmit Beamforming (RTB). However, the previously published implementations of REFoCUS do not address clutter from sidelobes and grating lobes present in the data before the recovery. This reduces image quality due to potentially strong sidelobes and grating lobes, particularly when using REFoCUS in combination with micro-beamforming and matrix array probes. Recordings from micro-beamforming probes may thus not be compliant with the existing REFoCUS methods. We propose to solve the sidelobes and grating lobe issues by introducing a reformulation of REFoCUS that performs multistatic data recovery and beamforming in the time domain, allowing spatial weighting to remove clutter and noise. Spatial weighting is based on common beamforming principles and incorporates element directivity, dynamic F-number, beam geometry weighting, and grating lobe suppression. We also discuss how aperture sampling affects beamforming with REFoCUS. Spatially Weighted REFoCUS (SWR) and critical sampling of the transmit aperture show suppression of receive grating lobes in an in vivo setting with two different micro-beamforming matrix-array probes, leading to an increase in gCNR contrast from 0.44 to 0.96 in a fetal image and from 0.39 to 0.89 in a cardiac image.
{"title":"Universal REFoCUS Beamforming With Spatial Weighting","authors":"Anders Emil Vrålstad;Magnus Dalen Kvalevåg;Ole Marius Hoel Rindal;Svein-Erik Måsøy","doi":"10.1109/OJUFFC.2024.3398595","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3398595","url":null,"abstract":"REFoCUS (Retrospective Encoding For Conventional Ultrasound Sequences) offers great flexibility by enabling synthetic aperture beamforming from conventional ultrasound sequences. This flexibility is beneficial for many aspects in medical ultrasound beamforming, including e.g. combination of different transmit waves, distributed sound speed estimation and common-midpoint gathers. REFoCUS beamforming also has image quality comparable to state-of-art methods such as Retrospective Transmit Beamforming (RTB). However, the previously published implementations of REFoCUS do not address clutter from sidelobes and grating lobes present in the data before the recovery. This reduces image quality due to potentially strong sidelobes and grating lobes, particularly when using REFoCUS in combination with micro-beamforming and matrix array probes. Recordings from micro-beamforming probes may thus not be compliant with the existing REFoCUS methods. We propose to solve the sidelobes and grating lobe issues by introducing a reformulation of REFoCUS that performs multistatic data recovery and beamforming in the time domain, allowing spatial weighting to remove clutter and noise. Spatial weighting is based on common beamforming principles and incorporates element directivity, dynamic F-number, beam geometry weighting, and grating lobe suppression. We also discuss how aperture sampling affects beamforming with REFoCUS. Spatially Weighted REFoCUS (SWR) and critical sampling of the transmit aperture show suppression of receive grating lobes in an in vivo setting with two different micro-beamforming matrix-array probes, leading to an increase in gCNR contrast from 0.44 to 0.96 in a fetal image and from 0.39 to 0.89 in a cardiac image.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"15-26"},"PeriodicalIF":0.0,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10525686","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141084871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study demonstrated the first air-coupled pMUT using sol-gel PZT thin film that could deliver ultrasonic waves to mid-air. First, the deposition conditions for making PZT thin film with high remanent polarization were determined. Then, air-coupled pMUTs with resonance frequencies close to 40 kHz were designed using the circular plate model. According to the design, pMUTs with radii measuring $600~mu $ m to $775~mu $ m were fabricated to evaluate the acoustic output pressure. Among these, the pMUT with the $725~mu $ m radius achieved a maximum sound pressure output of 4.42 Pa at 3 cm above when driven with 10 Vpp, and the resonance frequency was 40.48 kHz. Finally, the output pressure of a phased array consisting of sol-gel PZT-based pMUTs with a $725~mu $ m radius was calculated using the k-Wave toolbox. The output pressure of the $11times 11$ pMUT array reached 365.62 Pa when focused at 3 cm above it. This result revealed that the output pressure of the proposed pMUT array could fulfill the requirement for most mid-air ultrasound applications.
{"title":"Development of an Air-Coupled Piezoelectric Micromachined Ultrasonic Transducer Using Sol-Gel PZT Thin Film for Fast-Prototyping","authors":"Ya-Han Liu;Hsiao-Chi Lin;Chih-Ying Li;Chien-Lun Kao;Han-Jen Hsu;Yeong-Her Wang;Chih-Hsien Huang","doi":"10.1109/OJUFFC.2024.3397630","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3397630","url":null,"abstract":"This study demonstrated the first air-coupled pMUT using sol-gel PZT thin film that could deliver ultrasonic waves to mid-air. First, the deposition conditions for making PZT thin film with high remanent polarization were determined. Then, air-coupled pMUTs with resonance frequencies close to 40 kHz were designed using the circular plate model. According to the design, pMUTs with radii measuring \u0000<inline-formula> <tex-math>$600~mu $ </tex-math></inline-formula>\u0000m to \u0000<inline-formula> <tex-math>$775~mu $ </tex-math></inline-formula>\u0000m were fabricated to evaluate the acoustic output pressure. Among these, the pMUT with the \u0000<inline-formula> <tex-math>$725~mu $ </tex-math></inline-formula>\u0000m radius achieved a maximum sound pressure output of 4.42 Pa at 3 cm above when driven with 10 Vpp, and the resonance frequency was 40.48 kHz. Finally, the output pressure of a phased array consisting of sol-gel PZT-based pMUTs with a \u0000<inline-formula> <tex-math>$725~mu $ </tex-math></inline-formula>\u0000m radius was calculated using the k-Wave toolbox. The output pressure of the \u0000<inline-formula> <tex-math>$11times 11$ </tex-math></inline-formula>\u0000 pMUT array reached 365.62 Pa when focused at 3 cm above it. This result revealed that the output pressure of the proposed pMUT array could fulfill the requirement for most mid-air ultrasound applications.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"27-36"},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10521570","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141084766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-29DOI: 10.1109/OJUFFC.2024.3371913
Martin Angerer;Jonas Welsch;Carlos D. Gerardo;Nicole V. Ruiter;Edmond Cretu;Robert Rohling
The objective of this work was to investigate changes in the acoustic characteristics of micromachined transducers caused by acoustic cross-coupling between cells. We used hexagonal, polymer-based capacitive micromachined ultrasonic transducers (polyCMUTs) consisting of 127 cells connected in parallel. The distances between the cells were varied, while the cell dimensions and number of cells remained constant. The resulting changes in characteristics were evaluated in terms of peak frequency $f_{pk}$ , fractional bandwidth $FBW$ , peak transmit sensitivity $S_{pk}$ and opening angle $Phi _{t}$ . The study relies on results from an analytic multicell model (MCM) which considers cross-coupling effects between cells through a mutual acoustic impedance matrix. The results are compared with finite element (FE) analyses and measurements on fabricated prototypes. The manufacturing processes used to produce the polyCMUT prototypes are explained in detail. We found significant changes in all acoustic characteristics: as cell spacing increases, $f_{pk}$ and $Phi _{t}$ decrease, while $S_{pk}$ gradually rises to about twice the initial value. The $FBW$ varies due to the change in $f_{pk}$ , peaking at small to intermediate cell-to-cell distances. While both modeling approaches cover the general effects, discrepancies in comparison to the measurements were identified. The FE model provided better fits than the analytic MCM, albeit at significantly higher computational costs. The effects on the acoustic characteristics were found strongest at lower frequencies and if many cells are in close proximity to each other. Hence, rotational symmetric or square transducers operating at lower frequencies are affected most. The results demonstrate that design approaches based on modeling single cells may lead to significant deviations from design goals. Both, analytic and FE models are suitable tools to estimate the effects of acoustic interactions and to predict the performance. This aids in meeting design requirements of micromachined ultrasound transducers consisting of multiple radiators.
{"title":"Studying the Effects of Mutual Acoustic Impedance on the Performance of Polymer-Based CMUTs","authors":"Martin Angerer;Jonas Welsch;Carlos D. Gerardo;Nicole V. Ruiter;Edmond Cretu;Robert Rohling","doi":"10.1109/OJUFFC.2024.3371913","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3371913","url":null,"abstract":"The objective of this work was to investigate changes in the acoustic characteristics of micromachined transducers caused by acoustic cross-coupling between cells. We used hexagonal, polymer-based capacitive micromachined ultrasonic transducers (polyCMUTs) consisting of 127 cells connected in parallel. The distances between the cells were varied, while the cell dimensions and number of cells remained constant. The resulting changes in characteristics were evaluated in terms of peak frequency \u0000<inline-formula> <tex-math>$f_{pk}$ </tex-math></inline-formula>\u0000, fractional bandwidth \u0000<inline-formula> <tex-math>$FBW$ </tex-math></inline-formula>\u0000, peak transmit sensitivity \u0000<inline-formula> <tex-math>$S_{pk}$ </tex-math></inline-formula>\u0000 and opening angle \u0000<inline-formula> <tex-math>$Phi _{t}$ </tex-math></inline-formula>\u0000. The study relies on results from an analytic multicell model (MCM) which considers cross-coupling effects between cells through a mutual acoustic impedance matrix. The results are compared with finite element (FE) analyses and measurements on fabricated prototypes. The manufacturing processes used to produce the polyCMUT prototypes are explained in detail. We found significant changes in all acoustic characteristics: as cell spacing increases, \u0000<inline-formula> <tex-math>$f_{pk}$ </tex-math></inline-formula>\u0000 and \u0000<inline-formula> <tex-math>$Phi _{t}$ </tex-math></inline-formula>\u0000 decrease, while \u0000<inline-formula> <tex-math>$S_{pk}$ </tex-math></inline-formula>\u0000 gradually rises to about twice the initial value. The \u0000<inline-formula> <tex-math>$FBW$ </tex-math></inline-formula>\u0000 varies due to the change in \u0000<inline-formula> <tex-math>$f_{pk}$ </tex-math></inline-formula>\u0000, peaking at small to intermediate cell-to-cell distances. While both modeling approaches cover the general effects, discrepancies in comparison to the measurements were identified. The FE model provided better fits than the analytic MCM, albeit at significantly higher computational costs. The effects on the acoustic characteristics were found strongest at lower frequencies and if many cells are in close proximity to each other. Hence, rotational symmetric or square transducers operating at lower frequencies are affected most. The results demonstrate that design approaches based on modeling single cells may lead to significant deviations from design goals. Both, analytic and FE models are suitable tools to estimate the effects of acoustic interactions and to predict the performance. This aids in meeting design requirements of micromachined ultrasound transducers consisting of multiple radiators.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10453524","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140114040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-22DOI: 10.1109/OJUFFC.2023.3344372
Mohammad Mohajery;Sebastien Salles;Torvald Espeland;Solveig Fadnes;Lasse Lovstakken
The mechanical wave (MW) propagation velocity in the heart is related to the tissue stiffness and its measurement mainly relies on manual evaluation of the 1D wave projection. This study presents an automated method for 3D wave visualization and velocity estimation in the heart using 3D ultrasound imaging of the left ventricle (LV). High-quality (HQ, 19 vps) and high-frame-rate (HFR, 823 vps) volumes were acquired. Deep learning models automatically segmented the LV and extracted the apical standard views from the HQ data which were used to derive the anatomical M-lines and myocardial segmentation. The clutter filter wave imaging (CFWI) and tissue Doppler imaging (TDI) generated wave propagation maps from HFR data, and the aortic valve closure (AVC) and atrial contraction/kick (AK) waves were automatically detected. LV segmentation and anatomical M-lines were used for 3D wave propagation extraction and its 1D projection, respectively. The 1D wave propagation velocity was determined through automatic slope detection, while the 3D velocity map was derived from the gradient of the time-of-flight (TOF) map. Results showed varying 1D velocity across views and myocardial regions, with the AVC propagation velocity surpassing that of the AK wave. The pipeline remained stable and generated results consistent with expert measurements. Comparing 3D and 1D propagation highlighted errors from 1D projection and demonstrated the benefits of the 3D method in assessing regional velocities and the validity of the 1D approach. This study demonstrated an automatic evaluation of 3D MW propagation velocities in the entire LV, leading to improved accuracy and standardized measurements of myocardial tissue properties.
心脏中的机械波（MW）传播速度与组织硬度有关，其测量主要依靠人工评估一维波的投影。本研究提出了一种利用左心室三维超声成像进行心脏三维波可视化和速度估算的自动化方法。研究人员采集了高质量（HQ，19 vps）和高帧频（HFR，823 vps）容积。深度学习模型自动分割左心室，并从 HQ 数据中提取心尖标准视图，用于推导解剖 M 线和心肌分割。杂波滤波成像（CFWI）和组织多普勒成像（TDI）从 HFR 数据中生成波传播图，并自动检测主动脉瓣关闭波（AVC）和心房收缩/踢波（AK）。左心室分割和解剖 M 线分别用于三维波传播提取和一维投影。一维波传播速度是通过自动斜率检测确定的，而三维速度图则来自飞行时间（TOF）图的梯度。结果显示，不同视图和心肌区域的一维速度各不相同，AVC 波的传播速度超过了 AK 波。管道保持稳定，生成的结果与专家测量结果一致。对比三维和一维传播，突出了一维投影的误差，证明了三维方法在评估区域速度方面的优势和一维方法的有效性。这项研究证明了三维 MW 传播速度在整个左心室的自动评估，从而提高了心肌组织特性测量的准确性和标准化。
{"title":"Automated 3D Velocity Estimation of Natural Mechanical Wave Propagation in the Myocardium","authors":"Mohammad Mohajery;Sebastien Salles;Torvald Espeland;Solveig Fadnes;Lasse Lovstakken","doi":"10.1109/OJUFFC.2023.3344372","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3344372","url":null,"abstract":"The mechanical wave (MW) propagation velocity in the heart is related to the tissue stiffness and its measurement mainly relies on manual evaluation of the 1D wave projection. This study presents an automated method for 3D wave visualization and velocity estimation in the heart using 3D ultrasound imaging of the left ventricle (LV). High-quality (HQ, 19 vps) and high-frame-rate (HFR, 823 vps) volumes were acquired. Deep learning models automatically segmented the LV and extracted the apical standard views from the HQ data which were used to derive the anatomical M-lines and myocardial segmentation. The clutter filter wave imaging (CFWI) and tissue Doppler imaging (TDI) generated wave propagation maps from HFR data, and the aortic valve closure (AVC) and atrial contraction/kick (AK) waves were automatically detected. LV segmentation and anatomical M-lines were used for 3D wave propagation extraction and its 1D projection, respectively. The 1D wave propagation velocity was determined through automatic slope detection, while the 3D velocity map was derived from the gradient of the time-of-flight (TOF) map. Results showed varying 1D velocity across views and myocardial regions, with the AVC propagation velocity surpassing that of the AK wave. The pipeline remained stable and generated results consistent with expert measurements. Comparing 3D and 1D propagation highlighted errors from 1D projection and demonstrated the benefits of the 3D method in assessing regional velocities and the validity of the 1D approach. This study demonstrated an automatic evaluation of 3D MW propagation velocities in the entire LV, leading to improved accuracy and standardized measurements of myocardial tissue properties.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"210-222"},"PeriodicalIF":0.0,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10372587","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139676159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-21DOI: 10.1109/OJUFFC.2023.3342751
Arthur Chavignon;Baptiste Heiles;Vincent Hingot;Cyrille Orset;Denis Vivien;Olivier Couture
Ultrasound Localization Microscopy (ULM) enables imaging microvessels in the brain with a resolution of a few tens of micrometers in-vivo. The planar architecture of arterioles and venules was revealed with a 2D ultrasound scanner in the cortex of the rat brain. However, deeper in the brain, where the vascularization becomes tri-dimensional, 2D imaging remains limited by the elevation projection. In this study, volumetric ultrasound imaging was performed in the craniotomized rat brain to yield 3D ULM in vivo within 7.5 min of acquisition with a commercial system. For instance, it highlighted the thalamus or the circle of Willis with small vessels down to $21 ~mu text{m}$ . Microbubbles tracking also gave access to the 3D velocity vector of blood flow allowing to distinguish flow directions. Volumetric ULM resolved deep complex tri-dimensional vascular structures and was compared to 2D ULM. It is a safe, simple and repeatable system to image wide field of view in the brain.
{"title":"Deep and Complex Vascular Anatomy in the Rat Brain Described With Ultrasound Localization Microscopy in 3D","authors":"Arthur Chavignon;Baptiste Heiles;Vincent Hingot;Cyrille Orset;Denis Vivien;Olivier Couture","doi":"10.1109/OJUFFC.2023.3342751","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3342751","url":null,"abstract":"Ultrasound Localization Microscopy (ULM) enables imaging microvessels in the brain with a resolution of a few tens of micrometers in-vivo. The planar architecture of arterioles and venules was revealed with a 2D ultrasound scanner in the cortex of the rat brain. However, deeper in the brain, where the vascularization becomes tri-dimensional, 2D imaging remains limited by the elevation projection. In this study, volumetric ultrasound imaging was performed in the craniotomized rat brain to yield 3D ULM in vivo within 7.5 min of acquisition with a commercial system. For instance, it highlighted the thalamus or the circle of Willis with small vessels down to \u0000<inline-formula> <tex-math>$21 ~mu text{m}$ </tex-math></inline-formula>\u0000. Microbubbles tracking also gave access to the 3D velocity vector of blood flow allowing to distinguish flow directions. Volumetric ULM resolved deep complex tri-dimensional vascular structures and was compared to 2D ULM. It is a safe, simple and repeatable system to image wide field of view in the brain.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"203-209"},"PeriodicalIF":0.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10368081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139034310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-04DOI: 10.1109/OJUFFC.2023.3338570
Stefano Fiorentini;Svein-Erik Måsøy;Jørgen Avdal
In medical ultrasound, aberration is a phenomenon that causes distortion of the ultrasound wavefront as it travels through an inhomogeneous medium. Aberration has been investigated since the 1960s and is known as a major cause of image quality loss in several applications, such as abdominal, breast, transcranial, and cardiac imaging. In the attempt to improve image quality in the presence of aberration, research has focused on two fronts: to provide deeper understanding of the physics behind aberration, and to develop robust methods for aberration correction based on such knowledge. However, most of the work found in the literature is focused towards improving BMode image quality, whereas little attention is given to other modalities. The aim of this work is to investigate the effects of aberration on two established blood flow imaging and quantification modalities, Pulsed Wave (PW) Doppler and Color Flow. The study was carried out on phantom and in-vivo recordings, using acquisitions and aberration conditions commonly encountered in cardiac imaging. In this work, aberration was modeled as a near-field phase screen, allowing for easier design and manufacturing compared to more realistic models. The results indicate that, as in BMode imaging, aberration degrades signal-to-noise ratio and resolution. Moreover, the increased sample volume size can significantly affect mean velocity and variance estimates in Color Flow, especially in the presence of strong velocity gradients occurring laterally to the beam direction. Similar effects were observed in PW Doppler. The conclusion is that blood flow imaging and quantification modalities in cardiac applications can potentially benefit from the development of aberration correction methods.
{"title":"Analysis of Aberration Effects on Flow Imaging and Quantification in Echocardiography","authors":"Stefano Fiorentini;Svein-Erik Måsøy;Jørgen Avdal","doi":"10.1109/OJUFFC.2023.3338570","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3338570","url":null,"abstract":"In medical ultrasound, aberration is a phenomenon that causes distortion of the ultrasound wavefront as it travels through an inhomogeneous medium. Aberration has been investigated since the 1960s and is known as a major cause of image quality loss in several applications, such as abdominal, breast, transcranial, and cardiac imaging. In the attempt to improve image quality in the presence of aberration, research has focused on two fronts: to provide deeper understanding of the physics behind aberration, and to develop robust methods for aberration correction based on such knowledge. However, most of the work found in the literature is focused towards improving BMode image quality, whereas little attention is given to other modalities. The aim of this work is to investigate the effects of aberration on two established blood flow imaging and quantification modalities, Pulsed Wave (PW) Doppler and Color Flow. The study was carried out on phantom and in-vivo recordings, using acquisitions and aberration conditions commonly encountered in cardiac imaging. In this work, aberration was modeled as a near-field phase screen, allowing for easier design and manufacturing compared to more realistic models. The results indicate that, as in BMode imaging, aberration degrades signal-to-noise ratio and resolution. Moreover, the increased sample volume size can significantly affect mean velocity and variance estimates in Color Flow, especially in the presence of strong velocity gradients occurring laterally to the beam direction. Similar effects were observed in PW Doppler. The conclusion is that blood flow imaging and quantification modalities in cardiac applications can potentially benefit from the development of aberration correction methods.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"194-202"},"PeriodicalIF":0.0,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10341282","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138577996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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