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Atherosclerosis in the carotid artery (CA) elevates the risk for cerebral events. Strain imaging has demonstrated to be a technique capable of identifying plaque composition. For strain imaging of carotid cross-sections, compound techniques have been developed to solve the poor strain estimation quality perpendicular to the ultrasound beam direction. This study assesses the performance of radial and...
Ultrasound-mediated drug delivery using microbubbles is a growing field with applications ranging from targeted chemotherapy to permeating the blood brain barrier. Despite the potential clinical impact of this technique, the precise parameters needed to reliably induce cell sonoporation, or increased cellular permeability, are not well understood. The goal of this work is to use high frame rate imaging...
Partial substitution of Al by Sc in AlN wurtzite films leads to a strong enhancement of the piezoelectric properties as long as the wurtzite phase is maintained. This is very promising for improving piezoelectric MEMS devices and enlarging their application range. Nucleation of (0001)-AlScN works particularly well on Pt (111) thin films. However, in some applications, the growth on insulating substrates...
It was estimated that annual cost of measurable medical errors was higher than $17 billion in 2008. Phantoms are objects manufactured using a tissue mimicking material (TMM) and largely used to test protocols and mimic clinical environment for medical training. TMM should reproduce at least one biological property to allow the association with clinical situation. The gel made by the copolymer styrene-ethylene/butylene-styrene...
Measuring broadband signals demands complex calibration of a detector over a sufficient bandwidth. For inertial cavitation emissions, the shock waves will be convolved with the transfer function of the hydrophone, and introduce artefacts to the measurement. Use of appropriately calibrated detectors would thus facilitate meaningful comparison of the cavitation emission data reported from groups using...
Investigating biomechanical properties of the cornea can have many clinical applications, including the diagnosis of keratoconus and post-refractive keratectasia. However, ascertaining the biomechanical properties of cornea remains a challenge because of the low resolution of currently available modalities cannot provide a point-to-point stiffness mapping of cornea. In this study, we reported a high-resolution...
Acoustic wave characteristics are numerically investigated and compared in AlN/ZnO/diamond and Al2O3/GaN/sapphire with Pt electrodes. These structures have been previously reported as candidates for application in packageless sensors. They include a low-velocity guiding piezoelectric layer sandwiched between two high-velocity materials. The anisotropy of the combined materials, their symmetry and...
In the last decade the number of beamforming methods has exploded. Many innovative ideas have been proposed, but we lack the tools to compare the different techniques efficiently. The PICMUS challenge (IUS 2016, Tours) was a pioneering step that made clear that two things are required to establish a fair comparison: a common data format, and a body of methods to process that data.
Histotripsy uses high-pressure, microsecond-length pulses to generate cavitation microbubbles to fractionate targeted tissue. After the collapse of a cavitation cloud, remnant microbubbles can persist for a second or longer before passively dissolving. These bubbles can act as seed nuclei for subsequent cavitation events reducing treatment efficiency because the nuclei are not well distributed through...
In last decade, composite materials have been used widely in industrial area. Structural elements produced from the composites possess more complicate mechanical properties than components manufactured from isotropic materials. Therefore, imaging algorithms of defects in anisotropic materials have not yet been developed well, because of anisotropic properties of elastic media affect much on the shape...
Histotripsy is considered a non-invasive therapeutic modality capable of mechanically fractionating tissue using cavitation bubbles induced by high intensity focused ultrasound pulses. Histotripsy-induced cavitation region over relatively large focal volume is effective in treating sizable lesion, while compromising its treatment precision. We demonstrate high-precision cavitation treatment using...
Patients with a 70–99% stenosed carotid artery will undergo surgery to prevent rupture of the plaque. However, the degree of stenosis does not determine the vulnerability of the plaque, since vulnerability depends on the plaque's morphology, mechanical properties and the force acting on the plaque. Mechanical models of the carotid artery can improve decision-making of the surgeon by quantifying and...
Energy harvesting from surrounding electromagnetic wave can satisfy the increasing demand of trillions of wireless sensors for IoT. RF energy harvesting is generally achieved by RF-DC conversion using a rectifying antenna (called rectenna). For weak RF signal, however, RF-DC conversion efficiency significantly decreases because weak RF signal cannot activate the diode in the rectenna. Therefore, in...
Shear wave elastography is useful for quantitatively evaluating tissue elasticity by measuring the speed of a shear wave induced within the body by acoustic radiation force. We proposed a pushing-and-tracking sequence, coded push-pulse excitation to increase the signal-to-noise ratio (SNR) of the observed shear wave propagation without increasing measurement time and push-pulse amplitude1). In this...
Reactive oxygen species (ROS) are hypothesized to play a role in the sonoporation mechanisms. Sofar, the production of ROS has been mainly reported inside the cytoplasm of cells after sonoporation. However, the acoustical phenomenon triggering the production of ROS is unknown. In this context, we investigated whether the interaction between microbubbles (MBs) and ultrasound (US) induce the production...
Pulmonary embolism (PE) is the third-leading cause of death from cardiovascular disease. Currently, PE is treated via catheter-delivered, ultrasound-enhanced thrombolysis using side-fired, low-intensity ultrasound energy (0.5 W/cm2) at ∼2 MHz to reduce the required dose of thrombolytic drugs because of the enhanced drug penetration into the clot. However, several clinical studies have shown that the...
Hydroxyapatite (HAp) is a useful biocompatible material and is used for the surface coating of artificial bone. It has been reported that the oriented HAp promotes rapid recovery of the bone fracture[1], although most of coating HAp layers on the commercial artificial Titanium (Ti) bones are not oriented. As a new coating layer, our group has reported the highly oriented HAp film on Ti substrate fabricated...
A transparent transducer array is desired in backward-mode photoacoustic imaging (PAI). CMUT technology is especially suitable for this application because of its wide bandwidth and a wide selection of processing materials. We have previously demonstrated a single-element CMUT with an ITO bottom electrode for improved transparency. The device showed 40% to 70% optical transmission from 700 nm to 900...
The matching layer inserted between the front protection metal and piezoelectric layer has been designed when the protection metal is half-wavelength thick. This matching layer plays the role of a bonding layer. The optimum thickness ranges from λ/4 to 3λ/8 in the Mason model simulation, which has been confirmed by experiments. In the optimum range, the sensitivity was much higher and the bandwidth...
High-intensity focused ultrasound (HIFU) have been an attractive research topic for some time now. HIFU studies have started with single-element transducers, but using arrays provide the opportunity to scan the focal point electronically. Modular and scalable driving systems that can adapt to custom-made transducer elements to drive these arrays are needed and at the present time there are few such...
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