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This article reports on the fabrication and characterization of lambda-pitched piezoelectric micromachined ultrasound transducer (pMUT) arrays fabricated using a unique process combining conventional silicon technology and low cost screen printing of thick film PZT. The pMUTs are designed as 8 element membrane based devices dimensioned to operate in bending mode in the 1-10 MHz regime. The devices...
We report on piezoelectrically actuated 13 MHz silicon beam resonators operating in the fundamental length extensional BAW mode. The resonance is evoked using an aluminum nitride layer grown on top of the resonator. We demonstrate quality factors as high as Q~55000 in vacuum, and transduction factors of the order of eta~20 muN=V. The anchor loss is studied using designs with variations in the support...
High frequency ultrasound transducer arrays that can operate at frequencies above 30 MHz are needed for high resolution medical imaging. A key issue in the development of these miniature imaging arrays is the need for photolithographic patterning of array electrodes. To achieve this directly on a 1-3 piezocomposite requires not only planar, parallel and smooth surfaces, but also an epoxy composite...
This paper presents the latest development of high-frequency PZT film ultrasonic linear arrays. A PZT thick film of 22 mum in thickness was fabricated with a spin-coating method. The film was found to have a remnant polarization of 30 muC/cm2 and a coercive field Ec of 70 KV/cm. A high-frequency linear array was successfully fabricated with the film. The array shows a center frequency of 80 MHz and...
A novel technique for fabrication of linear arrays of high frequency piezoelectric Micromachined Ultrasound Transducers (pMUT) on silicon substrates is presented. Piezoelectric elements are formed by deposition of PZT ((PbZrxTi1-x)O3) into etched features of the silicon substrate such that the depth of these features determine the element thickness and hence the resonance frequency. The process leaves...
This paper presents a new high-efficiency ME composite transducer consisting of magnetostrictive Terfenol-D arrays, piezoelectric PZT arrays and a substrate. Magnetostrictive resonant unidirectional transducer (MRUDT) array groups and a piezoelectric unidirectional transducer (PUDT) array group are created inside the transducer while propagating the unidirectionality required for low loss and converting...
We report on the design, fabrication and characterization of piezoelectrically actuated single-crystal silicon plate resonators vibrating mainly in their bulk acoustic wave modes. Two resonator types are presented: one operates in the square extensional mode at 26 MHz with Q~18000 and motional resistance Rm~0.240 kOmega, while the other resonator features a resonance at 22 MHz with Q~51000 and Rm~1...
High frequency transducers/arrays made of piezo- composite materials have the advantages of lower acoustic impedances, which better match tissue and a flexibility that allows focusing without the use of an acoustic lens. However, developing a high-frequency piezo-composite material for such arrays is still a challenge due to the extremely small pillar dimensions required to avoid the interference...
A piezoelectric ultrasonic hydrophone array was fabricated using diaphragm transducer on Si substrates. A two dimensional (2-D) array of 8 times 8 elements with diaphragm transducer has been developed by XeF2 etching from the topside of Si. In this paper, we describe the fabrication process of the diaphragm transducer array. A finite-element analysis (FEA) was calculated to evaluate the resonant frequency...
This paper presents a passive and remote polymer- coated Love wave chemical sensor. A ST-90degX quartz was used as the substrate, which provides a shear horizontal surface acoustic wave (SH-SAW) with high shear velocity and larger piezoelectricity. A layer of polymethylmethacrylate (PMMA) was considered as the guiding layer owing to its lower shear velocity. The dispersion relationship of the Love...
High intensity focused ultrasound, HIFU has been used to non-invasively treat human tumors, such as uterine fibroids, prostate cancer, breast cancer, liver tumor, and brain tumor. However, the tumor in some organs can be moved by human breathing and heart beat, which may cause the ablation and damage of normal tissues during the sonication of HIFU. The purpose of this study was to develop a HIFU phased...
An ultrasonic piezoelectric transducer to cut the human tissue or to remove the spinal disc is envisioned to improve efficiency and facilitate the surgeons work. Three genetic algorithms have been developed. The first one is based on conditional genetic operators, the second one is based on a specific crossover operator definition with a local search method, and the third is a combination of both...
In this paper a piezoelectric composite based micromachined ultrasound transducer (PC-MUT) technology is presented for fabrication of PMN-PT single crystal piezoelectric composite transducers. Micromachined PMN-PT single crystal 1-3 composites with resonance frequencies of 15 MHz-75 MHz were fabricated and characterized with coupling coefficient of 0.67-0.79. Transducers with a frequency of 75 MHz...
The photoresist SU-8, often used in microtechnology, has been acoustically characterized at a frequency of 1 GHz thanks to thin-disk piezoelectric ZnO transducers. Acoustical characterization of SU-8-based nanocomposites made of SU-8 and nanosize TiO2 and/or SrTiO3 particles is presented. These nanocomposite materials would be used to achieve acoustical matching between silicon and water at a frequency...
We propose in this paper a modified KLM electroacoustic model of transducer that enables to take into account the effect of a mechanical pre-stress. Then, a numerical study of the electro-acoustic parameters for lithium niobate piezoelectric material (coupling coefficient, velocities and associated polarizations, and electrical input impedance) is led with regard to the azimutal and incident angles,...
Fresnel lens design has been used for annular arrays. In this case, the surface area of each concentric ring is the same. By doing so, the phase shift between adjacent transducer elements remains constant when focusing at depth. Recently, a 40 MHz transducer has been proposed with increased bandwidth by varying the thickness of the piezoelectric material from center of the transducer to the edge....
High frequency ultrasonic transducers were fabricated using lead indium niobate-lead magnesium niobate-lead titanate (0.24PIN-0.44PMN-0.32PT) as the active piezoelectric material. The measured center frequency and bandwidth of the device were 35 MHz and 48 % respectively. The electrical impedance magnitude was 71 Omega and phase was - 38deg. Insertion loss was measured to be 15 dB. A phantom which...
We propose a system to wirelessly convey electric energy through a thin metal wall. Two piezoelectric transducers are used to realize energy transformation between electric and mechanical, and a rechargeable battery is employed to store the transmitted energy, both are integrated as a system through a modulating circuit. A synchronized switch harvesting on inductor (SSHI) in parallel with the transducer...
This work describes the finite element analysis of a piezoelectric acoustic levitator. The acoustic levitator consists of a Langevin transducer and a steel reflector. The finite element method is used to determine the electrical impedance, the transducer face displacement and the acoustic radiation potential that acts on a small sphere. The numerical electrical impedance is compared with that obtained...
Energy harvesting systems based on the transformation of acoustic vibrations into electrical energy are increasingly being used for niche applications due to the reduction in power consumption of modern day electronic systems. Typically these applications involve extracting energy at remote or isolated locations where local long term power is unavailable or inside sealed or rotating systems where...
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