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As new flow imaging methods are actively being developed, there is a growing need to devise appropriate phantoms that can holistically assess the accuracy of the derived flow estimates. Straight-tube models simply cannot serve this purpose, nor can spinning discs that simulate tissue motion instead of flow dynamics. Anthropomorphic bifurcation models are also not ideal, because their geometry does...
Amorphous thin films are used as components of acoustic resonators because they could control temperature coefficient of resonator. Because elastic constants of thin films are often different from those of bulk materials, the direct measurement of sound velocity and temperature coefficient of velocity (TCV) for individual thin films becomes important in designing resonators. Because The TCV of amorphous...
In most studies on vascular shear wave imaging (SWI), longitudinal section is mainly concerned, and the radial motion and reflected waves are not considered in cross section. It is important to investigate the SWI in cross section when evaluating the anisotropy of the vessel wall or the complete plaque composition. In our previous study, a novel method based on coordinate transformation and directional...
This paper presents an equivalent circuit model of a piezoelectric micromachined ultrasonic transducer (PMUT) array, combining an acoustic coupling model originally developed for capacitive micromachined ultrasonic transducer (CMUT) arrays and an electro-mechanical model of the individual PMUTs in the array. This model is experimentally validated with PMUT arrays of varied sizes and accurately predicts...
Modification of dissolved gas content by nucleation of acoustic droplet vaporization (ADV) has been proposed for several therapeutic applications. Reducing dissolved oxygen could inhibit reactive oxygen species production during reperfusion of ischemic tissue, such as during coronary interventions to rescue myocardium. Localization of the effect may be achieved using intravascular ultrasound (IVUS),...
In this paper, we describe a 920 MHz band long range wireless SAW passive tag system (WSPTS) for vibration monitoring, which achieves more than 10m reading distance. For the purpose of structural health monitoring (SHM) of aging infrastructures (e.g. bridge, building, and so forth), passive wireless sensor systems are an attractive option because they are operated battery-less and almost maintenance...
Single Track Location Shear Wave Elasticity Imaging (STL-SWEI) creates high resolution shear wave speed maps by comparing the tissue motion at each tracking location between spatially-offset radiation force excitations. While STL-SWEI circumvents the resolution-limiting effects of speckle noise, it requires a series of excitation-tracking ensembles to build up a lateral field of view, increasing the...
Acoustic streaming effects are usually treated using perturbation theory by writing the field variables as perturbation expansions utilizing a small scale parameter and solving the ensuing equation systems. When conducting numerical simulations, this approach can help reducing the computational effort drastically. In most cases, the zero-order velocity is assumed to be zero, which is an applicable...
This paper presents the characterization of frequency response and mode shape at the 1st harmonic frequency of a Micro-Opto-Mechanical Acoustic Sensors (MOMAS) with a Mach-Zehnder Interferometer (MZI) readout system. In previous research, the static modeling and characterization has been demonstrated. In this paper, we investigate the capability of using MOMAS in ultrasound domain as a Micro-Opto-Mechanical...
Structure-property relationships in bulk materials can be important in establishing sensing methods to assess the state of material microstructure. This is particularly true for nuclear graphites since these materials can display anisotropy and can become oxidized under service conditions. Both anisotropy and oxidation-induced porosity can influence structural integrity and this must be confirmed...
Leukemia commonly leads to hypoxia in the bone marrow, which can then result in increased resistance to chemotherapy. However, the relationship between local hypoxia and disease progression is not well understood, and it is unclear whether hypoxia in the bone marrow is diffuse or focal in presentation. Spectroscopic photoacoustic (PA) imaging-based estimation of blood oxygen saturation (SO2) can be...
Spontaneous preterm birth, the foremost source of neonatal mortality, could potentially be prevented by objectively detecting abnormal changes in the uterine cervix. Shear Wave Elasticity Imaging (SWEI) biomarkers can quantify cervical softening that precedes vaginal delivery. This task can be complicated by biological (i.e., heterogeneity of cervical stiffness and pregnancy history) and experimental...
I describe recent progress in machine learning in medical ultrasound imaging. At a high level, the two technologies appear to be well-matched as the former attempts to make sense of complex patterns, and the latter can generate images of complex acoustic patterns. Thus, the general challenge to the image analysis practitioner is to design machine learning architectures that model the patterns in real...
Waveguiding layer acoustic waves (WLAW) technology is considered as a packageless solution for extreme miniaturization of acoustic wave devices. WLAW solution is also original and suitable for high-temperature applications. Indeed, the achievement of a stable high-temperature packaging still constitutes a technological lock, in particular regarding sealing performance. In this context, we consider...
To prevent unauthorized access to ICs, encryption can be enabled via extremely small and practically invisible microscale chips that are embedded inside the packaging of ICs. The authors lately demonstrated an acoustic power link based on AlN HBAR-like structures operating at 500 MHz [1]. Enormous acoustic losses introduced by air at such large frequencies necessitate tight coupling between the transducers...
Endoscopy and colonoscopy are the clinically recognised standards for imaging and diagnosis of diseases of the gastrointestinal (GI) tract. While 'scope-based approaches combine optical and ultrasound imaging to allow both imaging of the surface and full thickness of the bowel wall, they are limited in their ability to access the full length of the GI tract particularly the small bowel. Wireless video...
Flow cytometer plays a key role in cell sorting and analysis. For a higher detection precision, sheath flow is adopted to avoid the turbulent or vortex effect when the cell flowing through a capillary tube during the cell counting in many commercial cytometers. This method works well when the low flow velocity is relatively low. However, in order to have a higher analysis efficiency for clinical laboratories,...
It is critical to use a proper spatial sampling, otherwise images suffer from grating lobes. However, the cost of a medical ultrasound scanner is strongly related to the channel count of the receive electronics. This has led to channel reduction using multiplexing or in-probe pre-beamforming methods at the cost of image quality or frame rate. An alternative is to reduce the receive channel count and...
Accurate diagnosis of non-alcoholic steatohepatitis (NASH) is a critical issue in current clinical practice. Non-invasive diagnosis of NASH can be achieved by quantitative ultrasound (QUS), which requires a detailed understanding tissue-specific acoustic microstructure at cellular scale (i.e., 10 μm). Therefore, QUS methods would benefit from the knowledge of the acoustic properties of organelles...
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