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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...
Research on electrically-small antennas has been active for a long time, but so far it is still challenging to approach the Chu's limit that sets a constraint between the quality factor and the size of an antenna. Some researchers have made efforts to generate electromagnetic (EM) radiation by driving the magnetization of ferri-/ferro-magnetic materials, which can be efficiently realized via mechanical...
In this paper, we designed and simulated a multilayer planar resonator with target frequency of 2.5 MHz which is created over a row/column-addressed 2D CMUT array. We have shown through finite element modeling and simulations that a particle can be trapped and manipulated both in lateral and axial directions inside the fluid channel by activating CMUT elements; And calculated acoustic radiation force...
In this study, phononic crystals are employed to elastic waveguide transducers for controlling its beam patterns. When signals from the transducer array are inputted to a homogeneous waveguide, they are distorted as propagating due to generation of multiple wave modes and wave dispersion. For this reason, it is difficult to apply transducer array to manipulate the beam pattern of waveguide transducers...
Capacitive Micromachined Ultrasonic Transducer (CMUT) is a new type of ultrasound wave generator and detector. Analytical method is intuitive to understand the mechanism and physical effects through modeling of CMUT. To optimize the design procedures of CMUT membrane undergoing large deflection, a new analytical model with the consideration of the lateral force using Von Kármán equations is proposed...
Application of finite element methods (FEM) to the simulation of SAW devices has been constrained by the large number of degrees-of-freedom required, resulting in large memory usage and long computation times. Here, we propose a hierarchical cascading approach which takes advantage of the periodic structure typical of SAW devices. In this approach, each unique electrode period is modeled and simulated...
Viscoelasticity can be quantified in a model-independent manner with ultrasound-based methods such as Acoustic Radiation Force Induced Creep-Recovery (ARFICR) and Attenuation Measuring Ultrasound Shearwave Elastography (AMUSE). The extent of viscoelastic characterization with ARFICR and AMUSE have not been evaluated. In this study, finite element method (FEM) simulations and tissue mimicking phantoms...
This paper deals with advanced characterization approaches of thin piezoelectric materials enabling accurate modelling of low frequency (<50Hz) bimorph-based cantilever beam. Such structures had been widely studied and actual devices using bulk PZT materials had exhibited the best FoM (Figure of Merit) compared to thin and thick piezoelectric films generally used in MEMS industry. Bulk piezoelectric...
In Shear Wave Elastography, quantitative tissue characterization for dispersive shear wave propagation relies on phase speed analysis, which fits a theoretical relationship to the measured frequency-dependent wave velocity. However, this approach is challenged when applied to soft tissues with complex geometries and/or advanced material models, as there are no theoretical dispersion equations available...
The evaluation of the strain state is a usual practice to health monitoring mechanical structures. In a previous work, the time-reversal signal processing was theoretically and experimentally evaluated to measure the strain in plates. In this work, the theoretical analysis is extended to include acoustoelastic effects and border conditions. The influence of high longitudinal tensile stress on the...
This paper studies a design concept of a dual frequency ultrasonic transducer, in which we use different technologies for each band. A hybrid structure consisting of a piezoelectric stack used for the lower frequency (LF) band and a Capacitive Micromachined Ultrasound Transducer (CMUT) array placed on the top surface used for the higher frequency (HF) band is demonstrated by Finite Element Method...
This paper investigates sources for element to element variations in an ultrasound transducer array, measured by electrical impedance. A 3 MHz PZT transducer was made and diced into 53 elements, where the rotation speed of the dicing saw blade was varied between 10 000 and 30 000 rpm. The fabricated array was investigated under optical microscope, and electrical impedances of the elements were measured...
Sub-micrometer, periodic motion detection using blind source separation (BSS) via principal component analysis (PCA) is presented in the context of magnetomotive ultrasound (MMUS) imaging and Shearwave Dispersion Ultrasound Vibrometry (SDUV). In MMUS, an oscillating external magnetic field displaces tissue loaded with superparamagnetic iron oxide (SPIO) particles, whereas in SDUV, periodic tissue...
Shear wave inspection is generated from mode conversion of longitudinal waves, using a selected, angled wedge positioned between the transducer and the test specimen. However, in certain scenarios where access is restricted the combination of the transducer and the wedge can be too cumbersome for in situ deployment. In this work, a low profile, linear ultrasound array transducer is proposed to generate...
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