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Ultrasonic guided wave inspection has been in use for more than two decades. Its main advantage is that large sections of pipes can rapidly be screened. However, large area coverage comes at the cost of reduced resolution. Higher resolution can be achieved at higher frequencies-thickness products (> 300 kHz∗mm in steel), where more wave modes are excited; however, this makes the received signals...
Lithium (Li) has long been known to be the best anode material for rechargeable batteries, however, lithium metal batteries (LMB) have never been commercialized due to dendrite formation, resulting in thermal runaway and fire or explosion. During charging, Li ions deposit onto Li anode from the cathode via electrolyte. However, the deposition is not uniform due to the inhomogeneous ion distribution...
Increased myocardial stiffness is characteristic of many diseases, leads to a loss of diastolic function, and is a cause of diastolic heart failure (DHF). Methods to estimate myocardial stiffness include Shear Wave Elastography (SWE). Currently, ultrasound-based cardiac SWE includes acoustic radiation force (ARF)-based methods; however, the in vivo generation and detection of shear waves in myocardium...
Noninvasive imaging of physiologic currents in the body is limited by poor spatial resolution due to the ambiguous conductivity distribution between the current sources and recording electrodes. Acoustoelectric imaging (AEI), based on the interaction between pressure and resistivity, provides higher spatial resolution. Although we have demonstrated AEI of the cardiac activation wave in the live rabbit...
Diverging wave imaging is the most prominent transmit sequence in fast cardiac imaging. Indeed, as this type of ultrasound transmit insonifies a significant part of the region of interest at once, less transmit events are required to reconstruct an entire image leading to an improved time resolution. However, the flipside of this approach is that image quality reduces in terms of spatial resolution,...
Elastic properties of the ocular tissues are significantly affected by intraocular pressure (IOP) in the eye. For example, the speed of the elastic wave in the cornea dramatically increases with IOP. In our previous studies using ultrasound shear wave imaging we demonstrated that, for the lens, the increase in IOP does not result significant changes in the wave velocity. Compared with ultrasound imaging,...
We have studied C-mode and B-mode imaging using high-frequency ultrasonic waves through a thin fiber for direct observation of the microscopic image of tissue. We reported previously that the C-mode images of the tissue on the glass and B-mode image of animal bone placed in water were obtained using a fused quartz fiber as the needle-type ultrasound probe. In this paper, we propose a method for the...
Photoacoustic (PA) imaging aims for the reconstruction of acoustic sources that originate in pulsed light absorption. While the speed of sound (SOS) in biological tissue is heterogeneous, standard reconstruction algorithms usually assume a constant SOS. This results in deformations of the reconstructed sources, which are referred to as aberration and can have a severe impact on the spatial resolution...
One of the primary motivations for using ultrasound reflectometry for fingerprint imaging is the promise of increased spoof resistance over conventional optical or capacitive sensing approaches due to the ability for ultrasound to determine the elastic impedance of the imaged material. A fake 3D printed plastic finger can therefore be easily distinguished from a real finger. However, ultrasonic sensors...
For many diseases, such as cancer, simultaneous imaging of different targets can lead to improved diagnosis, better patient prognosis, and therapy guidance/monitoring. PET-CT multiplexing can be cumbersome, costly, and involve radiation exposure. Other modalities such as fluorescent imaging lack clinical and pre-clinical relevance. Therefore, clinically relevant multiplexed imaging is of interest...
Piezoelectric ultrasonic motors (PUMs) are based on the concept of driving the runner by a mechanical vibration excited on the stator via the converse piezoelectric effect. They exhibit merits of small size, simple structure, quick response, high accuracy and resolution, self-locking when power off and a lack of electromagnetic radiation. The linear PUMs become the research focus in recent years as...
The k-Wave MATLAB toolbox is widely used to conduct medical ultrasound simulations. It uses a Fourier collocation method to numerically solve the governing model equations, and introduces sources by adding acoustic pressure at points on an orthogonal grid. This approach introduces two errors when sources don't exactly align with the grid. These are phase errors arising from shifting source points...
Pulse wave velocity (PWV) is a reliable index of arterial stiffness. To date, reflected pulse wave interference is still a major challenge for regional PWV estimation using ultrasound imaging methods. In this study, a high-resolution Radon transform (HRT) method is proposed to eliminate the reflected wave interferences in PWV estimation.
We have previously proposed the use of acoustic microbubble delivery in blood vessels to improve the efficacy of acoustic targeted drug therapy. The technical requirement is the detailed visualization of the blood vessel network for navigation around a target such as a tumor. For this purpose, we have used three-dimensional (3D) Doppler-mode volumes to obtain the blood vessel structure. However, since...
Previous study has demonstrated that pulsed HIFU with tens of microseconds pulse duration (PD) and 10kHz PRF is effective for cavitation generation. Meanwhile, with the assistance of PFC nanodroplets, cavitation can be further enhanced. Despite of higher efficiency, we also need cavitation to be precisely controlled and confined for sake of therapeutic safety, especially during the implementation...
The constantly rising demand for higher data rates is addressed by advanced communication standards like carrier aggregation (CA) in combination with LTE. The increased complexity of the RF frontend has put tremendous pressure on improving linear performance of BAW filters over the last years. On top of that a large number of intermodulation (IMD) specification have been added to safeguard all CA...
Rodents are used extensively in research to study disease and evaluate drugs. Preclinical imaging systems allow for non-invasive assessments of animals. High frequency ultrasound systems have emerged over the last 15 years as valuable tools for evaluating numerous diseases and organs. When compared against other anatomical imaging systems, such as MRI and CT, ultrasound is the most cost effective,...
Displacement estimation is a critical component of elastography. The measurement of sub-resolution displacements relies on high cross-correlation (CC) between repeated collinear RF acquisitions. CCs are degraded by common sources of acoustic noise, such as reverberation clutter, in addition to the displacement of scatterers within the radiation force field. CCs are also degraded spatially across the...
In this paper, we fabricated a hybrid on-chip acoustic and field-effect device to investigate the acoustic carrier transportation in graphene. The device fabrication exploited aluminum nitride (AlN)-based surface micromachining process on a silicon wafer, facilitating an integration of a surface acoustic wave (SAW) delay line and a graphene field-effect transistor (GFET). The SAW device induced an...
Multi-frequency transducers may have a number of emerging applications including multi-scale imaging, superharmonc contrast imaging and imaging-therapy applications. For imaging-therapy applications low-frequencies are typically needed for therapeutic heating or contrast agent destruction, while higher-frequencies are required for high-resolution imaging. However, development of these multi-frequency...
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