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A 100 MHz high resolution ultrasonic micro-transducer with a focal lens is designed for medical imaging based on monocrystalline lithium niobate (LiNbO3) 36°/Y-cut. Finite element analysis is used to characterize the impulse response of this transducer and the stationary wave propagation. The results show that the focal lens attributes a lot to the directivity and the resolution. The wave derived...
A cylindrical traveling wave ultrasonic motor using outer excitation of two bending transducers is proposed in this paper. To avoid the drawbacks of conventional traveling wave ultrasonic motors, sandwich structure of PZT elements and d33 mode of PZT are used here. Working principle and design analysis by means of FEM method are detailed. A prototype motor has been fabricated and tested. Although...
In this paper, the design of a novel force controller which combines a neuro-fuzzy algorithm and a new contact ultrasonic probe is proposed. The fuzzy rules emulated network (FREN) has a control algorithm structure based on fuzzy IF-THEN rules. The contact probe is integrated in a Cartesian robotic system with the FREN force control. The contact probe is equipped with a 1 MHz frequency ultrasonic...
A method using broadband acoustic holography has been put forward to determining the reflection coefficients at arbitrary angles of incidence and compared with mono-frequent acoustic holography. The selection principle about every parameter has been deduced by numerical experiments on an aluminum board. Under an average error level of 10%, the radius of holographic plane should be greater than two...
Several test methods were evaluated in order to prove their suitability to detect voids, air bubbles, and adhesion failure in hollow-core composite insulators. Due to the relatively complex geometry of the insulators (bowed surface, shed-profile) and the criticality of even comparably small defects in high-voltage equipment, most of the methods did not provide satisfying results. Most promising seem...
Our study encompasses the phenomena associated with gradual symmetry reduction in phononic crystals (PnC). As the lattice of the PnC is deformed, transmission spectrum shows a change in the shape, position and the size of the band gaps. More important, a pass band inside the stop band develops. The practical feasibility of the phenomena for a sensor application of a PnC is demonstrated for the 2D...
Most biological tissues demonstrate nonlinear stress-strain relationships for sufficiently large deformations. A useful approach to characterizing and “optimizing” methodologies for studying nonlinear tissue elasticity is through experiments with tissue-mimicking phantoms. This work reports a phantom containing spherical inclusions created using information about the nonlinear behavior of agar-gelatin...
Shear Wave Induced Resonance Elastography (SWIRE) has been applied to confined mimicking breast tumors. These latter have been idealized as a spherical heterogeneity embedded in an homogeneous medium transmitting torsional shear waves. First, we present a theoretical model that served to verify and physically understand the resonance induction of spheres by torsional waves. Then, experimental measurements...
Deconvolution can be used to separate overlapping echoes from very thin layers. This way the reflection parameters of each particular echo can be obtained. Here, a noise insensitive time-domain deconvolution algorithm is presented, which can handle arbitrary and time-of-arrival dependent reference pulse shapes. This can reduce artifacts and enable proper detection of echoes with small amplitude, even...
This paper demonstrates the first measurement of the acoustoelectric (AE) interaction constant in cardiac tissue. Radiofrequency catheter ablation is performed in clinics as a standard treatment for cardiac arrhythmia with a high success rate. The procedure requires a detailed map of the heart's activation wave prior to treatment. Conventional electrical mapping techniques are slow, prone to registration...
Recent studies indicate that, despite absorption and heterogeneity, long cortical bones support guided waves propagation in the axial transmission configuration. Currently, there is a need to implement a robust method to extract guided mode wave numbers adapted to clinical requirements. Particularly the probe dimensions are limited by the accessibility to the skeletal site. Recently, an approach based...
Multiple modes excited in a single solidly-mounted ZnO bulk acoustic resonator would provide a multi-band resonator operating at non-harmonically-related frequencies in the GHz range. Ordinarily, separate devices with different electrode and reflector designs are needed to excite the thickness shear (TSM) and thickness-extensional (TE) bulk acoustic modes, each device optimized for a single mode....
Piezoelectric ultrasonic horn actuators are used in high power medical/surgical, automotive, food preparation, textile cutting, and material joining applications. Typically, these horn actuators are assembled by pre-stressing piezoelectric rings between the horn and backing layer using a pre-stress bolt. In the ultrasonic horn actuators presented in this paper the bolt was removed and the number of...
The long-established pace of progress in semiconductor electronics, expressed by Moore's Law, has led to new opportunities in medical ultrasound imaging. Traditionally, ultrasound systems have separated the transducer array from most of the electronic instrumentation, with multicore physical cabling in between. This avoids problems with electrical power, functional density, and communication bandwidth...
Infrared imaging of defects in materials has become a standard tool in nondestructive evaluation (NDE). The most recent version of this technology uses ultrasound to excite the defects by friction or other dissipative effects. This version is greatly enhanced by the use of "chaotic" sound.
Prony's method is effective for decomposing two-component pulses into two separate constituent pulses. This has applications for ultrasonic characterization of bone.
Micromachined high-frequency PMN-PT 1–3 composite ultrasonic annular arrays have been developed. The design, fabrication, and performance of the miniature transducers are described in this paper. PMN-PT single crystal 1–3 composite was produced using micromachining techniques. The area of the single crystal pillar is 9 µm × 9 µm. The space between each pillar was ∼5 µm; this region was filled with...
The object of this work is to present the concept of a composite material which consists of many closely packed tapered microrods. The material is intended to be used for ultrasonic transducer matching and fabricated using photolithographic methods. We find that for appropriate microrod diameter and taper, relative to the wavelength, the tapered microrod has a smooth continuous transition in its acoustic...
Ultrasonic echography and magnetic resonance imaging (MRI) are widely used medical diagnostic tools. The interest of combining them is based on the fact that the images are created in different ways and show different features of human tissue. Ultrasound creates images based on mechanical properties whereas MRI creates images based ultimately on chemical composition. MRI-guided focused ultrasound...
The sol-gel process is currently used to develop new materials with a wide range of applications in chemical and food industries. An ultrasonic self-calibrated method is used to evaluate the behavior of the nonlinear coefficient during the sol to gel reaction. The method uses a single piezoelectric transducer in burst echo-mode. Assuming a classical non linearity, the propagation of ultrasonic waves...
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