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Long term reliability has been a challenging issue in CMUT probe development. Kolo Medical Inc. has worked on improving reliability of CMUT probes for many years. Testing methods were developed and utilized to assess long term reliability and evaluate CMUT design improvements. A large amount of long term reliability test data were collected and analyzed.
Laser Induced Phased Arrays (LIPAs) use post processing to focus and steer the generated ultrasonic beam, synthesizing a phased array. Their principle is based on laser ultrasonics where lasers are used to generate and detect ultrasound. The technique is broadband, non-contact, and couplant free, making LIPAs suitable for large stand-off distances, inspection of components of complex geometries and...
Electromagnetic [1] and acoustic [2] metamaterials that exhibit linear dispersion at a nonzero frequency and a wave vector (k) of zero, leading to a conical dispersion surface or so-called Dirac cone dispersion, have been demonstrated recently. These materials display unusual behavior associated with the occurrence of a finite group velocity at k = 0, leading to a wave which propagates with a uniform...
To facilitate the development and application of ultrasound shear wave elastography (SWE) in arteries, it is necessary to understand the nature of shear waves (SWs) propagating in pressurized anisotropic tubes embedded in softer surrounding tissues and blood. Phantom models are widely used to study SWE in tubular settings mimicking arterial geometry without yet considering anisotropy. To investigate...
Ultrasound elastography is an effective modality for the delineation of thermally ablated regions after liver tumor treatments. Image contrast in elasticity imaging is based on differences in the Young's modulus of local tissue. In this work, we compare our previously introduced electrode displacement elastography (EDE) with a commercially available acoustic radiation force impulse imaging (ARFI)...
Fast cardiac imaging using diverging waves (DW) is receiving much attention. Coherent compounding is important to keep spatial resolution and CNR acceptable. Two approaches have been presented in literature to do so: i) the full aperture of the probe is used and the virtual focus is moved along an arc centered at the center of the probe (ARC); ii) a sub-aperture is used and the virtual focus is linearly...
Automated tow placement has become a widely-used fabrication technique, especially for large aerospace structures. Robotic heads lay down strips of pre-impregnated fiber (called tows) along programmed paths. While the intention is to lay adjacent tows abutted to one another, occasionally a tow is placed leaving a non-zero gap between it and the previously-placed tow. In order to preserve the intended...
Based on the least squares method which is arranged to the problem of fitting theoretical to experimental measured variables, such as phase velocities of acoustic waves and/or resonant frequencies, the environment of the minimum sum of squares (SSQ) has been analyzed, similarly to [1]. This is done by forming a “sensitivity matrix” (or Jacobian matrix: derivatives of measured variables with respect...
Parameters derived from the acoustic backscatter coefficient (BSC) represent quantification on an absolute scale and have been used to characterize tissue microstructure. This motivates their use to detect and quantify microstructural remodeling and ripening of the uterine cervix during pregnancy. This work systematically assessed the ex vivo human cervix microstructure and the effects of cervical...
Super-resolution techniques that localise isolated bubble signals first require detection algorithms to separate the bubble and tissue responses. This work explores the available bubble detection techniques for super-resolution of tumour microvasculature. Pulse inversion (PI), differential imaging (DI) and singular value decomposition (SVD) filtering were compared in terms of the localisation accuracy,...
Harmonic imaging techniques are widely used in B-mode abdominal imaging and motion tracking in shear wave elasticity imaging (SWEI) to reduce clutter and improve data quality. Harmonic imaging can be both signal-to-noise (SNR) and penetration depth (PD) limited, resulting in decreased diagnostic utility. This work evaluates B-mode harmonic imaging and SWEI harmonic tracking data quality between imaging...
We present an ultrasonic transit-time gas flow meter (UFM) that features a 40-kHz 8×8 2D-phased array for transmitting ultrasonic sound waves up- and downstream to two single element receivers. This allows us to electronically compensate for the well-known parasitic sound drift effect, resulting in larger measurement range and better signal-to-noise-ratio (SNR). The UFM fabricated consists of a pipe...
A row-column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. Since the transmit and receive 1-D arrays are orthogonal to each other, only one-way focusing is possible in each transmit or receive plane. By transmitting with row elements and receiving the echoes through column elements, a rectilinear volume in front of the array can be beamformed. This study suggests to use...
The development of ultrafast ultrasound imaging brings great opportunities to improve imaging technologies such as shear wave elastography and ultrafast Doppler imaging. In ultrafast imaging, there are trade-offs among image signal-to-noise ratio (SNR), resolution, and the high frame rate. Multiplane wave (MW) imaging is proposed to solve this tradeoff by encoding multiple plane waves with positive/negative...
The aim of this study is to investigate how the intracellular ROS responds to different degrees of sonoporation. Using a customized platform for 1.5-MHz ultrasound exposure (13.33-μs duration and 0.70-MPa peak negative pressure) and observing the dynamics of sonoporation and intracellular ROS at the single-cell level, we quantified the exogenous molecular uptake and intracellular ROS indicator to...
Performance of AlN-based electroacoustic devices directly tie with piezoelectric and metal electrode film quality. In this paper, sputter techniques for the reactive sputtering of AlN and ScAlN thin films, for the deposition of highly textured metal electrodes, and for the deposition of multilayer Bragg acoustic reflectors for SMR devices using dual-target S-gun magnetrons are described and some film...
Ultrasound based carotid strain imaging (CSI) developed in our laboratory utilizes physiological deformation in response to arterial pressure variations. We have shown that strain indices are capable of quantifying vulnerability of carotid plaque, enhancing their validity as vascular biomarkers. However, a critique of CSI has been the lack of normalization of the maximum and peak-to-trough strain...
A piezoelectric plate, poled along its thickness, that supports on its top surface a periodic grating of electrodes is considered. If wave propagation is assumed along the length of the plate, one demonstrates that an electrical Bragg band gap can be observed, depending on the electrical boundary conditions applied on the electrodes. This gap is associated with a discontinuity of the electric field...
Based on the linear relationship of channel data between synthetic transmit aperture (STA) and apodized plane wave (PW) firings, we previously proposed compressed sensing (CS) based STA (CS-STA) for linear array, which achieves higher frame rate and higher contrast-to-noise ratio (CNR) than STA while maintaining its high resolution. Because diverging wave (DW) instead of PW is usually adopted in phased...
Intravascular ultrasound (IVUS) is a well-established diagnostic method that has been applied frequently for providing high-resolution images of vessel wall and atherosclerotic plaques. Side looking transducer has been employed in a catheter for delineating the structure of vessel wall and lesions. However, it is difficult to get the flow distribution in the vessel by side looking transducer as the...
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