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Composite Overwrapped Pressure Vessels (COPVs) are widely used to contain high-pressure fluids. COPVs consist of a thin metallic liner covered with a composite material based on structural fibres. The main function of the liner is to avoid direct contact between composite and chemical agents which can degrade the resin matrix. In the filament winding process for COPV production, a metallic core is...
In ultrasound shear wave elastography (SWE), phase aberration can impact both push and tracking beams. From the literature, however, it is not clear whether performance loss in tissue stiffness reconstruction should be attributed more to push or tracking. To answer this question, we developed a research prototype based on a commercial ultrasound scanner EPIQ (Philips Healthcare, Andover, MA, USA)...
In this work we implement an experimental setup to quantify the angular momentum transferred by an acoustic vortex (AV) to disk-like samples of flat and helical surface. To produce an AV of m=1, we have fabricated a multitransducer of 123 ultrasonic elements (40 kHz) deployed on a triangular lattice and spatially shifted to create a radiant helicoid. The samples to be rotated by the AV were supported...
Acoustic beam diffraction phenomena for normal beam incidence to a viscoelastic plate, such as resonance frequency downshift, beam narrowing, and axial signal enhancement near certain leaky Lamb modes, have been demonstrated in recent years, as compared to plane-wave analyses. A close correlation between these phenomena and apparantly different guided-wave dispersion phenomena, including negative...
Acoustic radiation force has many applications. One of the related technologies is the ability to noninvasively expel stones from the kidney. To optimize the procedure it is important to develop theoretical approaches that can provide rapid calculations of the radiation force depending in stone size and elastic properties, together with ultrasound beam diameter, intensity, and frequency. We hypothesize...
Beamwidth broadening of an ultrasonic air-coupled transducer is performed by an emitter constituted of an electrostatic transducer and of a cylinder with an opening at the top covering the surface of the transducer. The acoustic emission is thus forced through a hole smaller than the diameter of the transducer's surface. In particular, a cylinder with an upper diameter of 10mm and a height of 5mm...
In shear compounding, shear waves are generated at various angles and individual elasticity maps are averaged to reduce noise and improve accuracy. The steered shear waves tilt the tissue motion direction therefore conventional plane wave tracking is not capable of capturing true shear wave amplitude and direction. The proposed method aligns the tracking beams with the shear wave angles, enables beam-axis...
A new concept for designing an integrated chemical multisensor with only two ports based on surface acoustic waves is presented. Following a principle from antenna theory an acoustic group antenna is assembled consisting of a number of identical interdigital transducers that are fed with currents of equal amplitude, but with a phase difference between neighbors. The propagation of the wave launched...
Acoustic waves in a phononic crystal (PnC) showed properties of band gaps and anisotropic propagation and promised many applications. By arranging the filling fraction of PnCs gradually in space, a gradient-index (GRIN) PnC was proposed to bend the wave propagation. GRIN PnCs were reported and applied as an acoustic lens to focus acoustic waves. Theoretically, this kind of lens has a hyperbolic secant...
We consider the problem of measuring short surface acoustic wave pulses directly in the time domain. The time-shearing differential optical interferometer setup described in this work is extremely sensitive and requires noise calibration. In order to test the accuracy of the response of the interferometer, different parameters of the experimental setup are varied. An input chirp is used to excite...
We have proposed a simple optical technique for visualization of ultrasound fields using the focused shadowgraph technique. To improve the quality of field images, effects of coherency in the illuminating light source were investigated using a laser diode (LD) and a light-emitting diode (LED). An experimental system with the two light sources was developed, and an acoustic field of a 2.5-MHz ultrasound...
Contrast plane wave (PW) imaging has been recently proposed as an improvement in contrast imaging mode. The capability of acquiring contrast images with a high frame rate and with limited bubble destruction [1] led to novel investigation approaches such as the tracking of single bubbles in motion [2][3]. Some of these studies are based on classical contrast sequences using Pulse Inversion (PI) [2]...
This paper presents the modeling and characterization of piezoelectric micromachined ultrasound transducers (PMUT) based on a three-dimensional dome shaped structure fabricated by a lithographic process. The transducer array is based on a high performance PZNT film integrated in a 3D dome shaped structure, which forms the basic resonator cell of the transducer. Acoustic and electromechanics simulations...
Mechanisms for non-invasive target drug delivery using microbubbles and ultrasound have attracted growing interest. Microbubbles can be loaded with a therapeutic payload and tracked via ultrasound imaging to selectively release their payload at ultrasound-targeted locations. In this study, an ultrasonic trapping method is proposed for simultaneously imaging and controlling the location of microbubbles...
The spot size of HIFU lesion depends on many parameters like size of the transducer, frequency of operation, sonication time etc. A recently developed CMUT based HIFU application for corneal keratoplasty require high localized temperature rise within a very small confined area as short as 300–500µm in length. To simplify the electrical connection requirements for this relatively small sized array,...
Implementation of 3D high frame rate (HFR) tissue Doppler imaging (TDI) typically requires a fully wired matrix probe. However, such probes remain impractical for use in a clinical setting. Therefore, clinical matrix arrays rely on sub-aperture (SAP) beamforming. This makes diverging wave (DW) imaging challenging as side- and grating-lobes arise from the simultaneous reconstruction of image lines...
This paper reports on the design and fabrication of a novel transducer structure called ultrasonic projector. The concept of an ultrasonic projector is first introduced. Then, the design of basic functional prototypes is discussed and characterization results are shown. Finally the projector concept is extended to structure capable of producing a focused ultrasonic beam shape. Design and characterization...
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