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Liquids density measurements are highly required in both research and industrial applications, from process control in petrochemical industry to product monitoring in food processing. Commercial devices are often expensive or unwieldy; therefore, in a previous work, a cheap and handy resonant sensor, based on a piezoelectric bimorph, was introduced. The operating principle is based on the variation...
A 360° fully functional endoscopic ultrasound radial array has been fabricated and evaluated. Transducer was specially designed to match the endoscope structure, which has a 10.5mm outer diameter, a 7.5mm inner diameter and a system connecting cable measuring 3.5m. Considering the size limitation in endoscopic application and transducer fabrication capability, two transducer designs with 192 and 252...
It has been shown in previous works that Capacitive Micromachined Ultrasonic Transducers (CMUT) could be an attractive alternative for the development of galvanically isolated transformers. These devices are ultrasonic transformers made of two CMUT arrays placed on each side of a silicon substrate. The resonance mode associated with the thickness of the substrate is used to transmit the acoustic signal...
This contribution is concerned with a technique to precisely measure the physical dimensions of flaws in solid specimen by pulse-echo mode acoustic microscopy. We have implemented a synthetic aperture focusing technique (SAFT), which is based on a semi-numerical simulation approach (SIRFEM). In acoustic microscopy, one normally applies single-element transducers with center frequencies above 10MHz...
Combining ultrasound measurements with finite element models (FEMs) is a novel technique to assess mechanical material parameters of vasculature. The stiffness of the FEM is calibrated iteratively until the displacements of the FEM match those measured by US. However, the influence of surrounding tissue, e.g. the spine in the case of abdominal aortas, is not taken into account. These could have a...
Effects which arise as a result of Hertzian contact between adjacent spheres of a granular chain can potentially change the nature of a signal as it propagates down the chain. The possibility thus exists of generating signals with a different harmonic content to the signal input into one end of the chain. This transduction mechanism has the potential to be of use in both diagnostic and therapeutic...
In a recent paper it has been shown that the effective nonlinear constant which is used in a P-Matrix approach to describe third-order intermodulation (IMD3) in surface acoustic wave (SAW) devices can be obtained from finite element (FEM) calculations of a periodic cell using nonlinear tensor data [1]. In this paper we extend this FEM calculation and show that the IMD3 of an infinite periodic array...
Skin represents a complex structure for the quantification of viscoelastic (VE) properties using shear waves. Wave propagation through skin has been modeled as propagating both as a Lamb wave and as a Rayleigh wave, but both assumptions are limited due to the structure of the skin, which is a multi-layered tissue. This complexity of structure makes it difficult to accurately assess the relative contributions...
A sensor based on torsional waves is proposed, designed and validated to quantify elastic constants of soft tissue. The proposed transducer design is able to deploy a shear wave elastography technique that accurately quantifies the shear viscoelastic moduli of the tissue, which, as opposed to compression waves, are strongly dependent on the stroma architecture, thus serving as a new biomarker.
In this work a causal P-matrix method for leaky SAW(LSAW) devices and the determination of the thereto needed COM-parameters slowness s and reflection r are presented. As a consequence of causality s and r in general are complex. The imaginary parts of reflection and slowness are interpreted as the exchange of energy between SAW and BAW. A relation of energy conservation between imaginary parts of...
A design of a 4×4 ultrasonic phased array working in flexural mode is presented. The array consists of an elastic metal sheet, a baffle with 16 holes, a back plate and 16 piezoelectric discs. The active area of each flexural array element is defined by the diameter of the holes of the baffle and the back plate provides an additional clamped-edge-like boundary condition through the baffle for each...
In ultrasound imaging, cross coupling of transducer elements through the medium has significant effect on the frequency response, thus affecting the quality of the ultrasound image. In Side-Looking Intravascular Ultrasound (SL-IVUS) imaging a radial image of the vessel wall is formed using a transducer array in a cylindrical configuration. Recent advances in Capacitive Micromachined Ultrasound Transducer...
This paper reports research into the use of a crossed-electrode two-dimensional thick film lead zirconate titanate ultrasonic transducer array for particle manipulation under the control of electronics based on field programmable gate arrays. The array consists of 30 × 30 transducer elements defined by electrode crosspoints and works at approximately 7.25 MHz. Laser vibrometry of the array surface...
This paper proposes a frequency domain analysis (FDA) based on the finite element method (FEM) for calculating reflector scattering characteristics of SAW tags. This method is applicable not only to devices employing conventional single-crystal substrates but also multi-layered ones. First, reflection characteristics are calculated for a short reflector on 128°YX-LiNbO3 and compared with the result...
A theoretical method is proposed to evaluate the creep damage in a 91 steel by using ultrasonic nonlinear technique. A 2-dimensional finite element model is developed to simulate the creep damage of steel P91 and the ultrasonic wave propagation through the degraded material. The micro-structural changes in the degraded material cause the distortion in the ultrasonic wave, and this material's nonlinearity...
MEMS piezoelectric energy harvesters, due to their unique features in power density and ease of fabrication, are known as one of the most promising solutions for providing unlimited power sources for low-power electronic applications. In this paper, the analytic equations to estimate generated voltage amount by a piezoelectric cantilever under various vibrations are presented. The comparison between...
Accurate diagnostics of stenosis and blood flow distribution in carotid arteries requires transducers capable of producing 3D volume images with high frame rate for real time imaging. In the process of designing a matrix probe, an important goal is to realize the acoustic stack with high sensitivity and bandwidth. In this study, we employ a finite element analysis to evaluate the effect of sub-dicing...
VisR ultrasound is an acoustic radiation force (ARF)-based imaging method that fits induced displacements to a 1D mass-spring-damper (MSD) model to estimate the ratio of viscous to elastic moduli, τ, in viscoelastic materials. A source of error in VisR τ estimation is complex and interrelated 3D system inertia. We hypothesize that error due to system inertia may be reduced by minimizing the volumetric...
Large-scale multi-frequency capacitive micromachined ultrasonic transducer (CMUT) arrays consist of thousands of closely packed interlaced large and small membranes for applications such as super-harmonic imaging, multi-band operation, imaging-therapy, contrast and photoacoustic imaging. An accurate nonlinear lumped equivalent circuit model including the effects of the self and mutual acoustic interactions...
The paper presents modelling and finite element simulation of a surface acoustic wave (SAW) motor based on dual friction-drive (DFD). The DFD SAW motor comprises of a flat cuboid slider tightly held between two identical piezoelectric stators typically made of lithium niobate facing each other, each stator having an interdigital transducer (IDT) fabricated on its either side. A sinusoidal excitation...
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