Дисертації з теми "Piezoelectric Micromachined Ultrasound Transducers"
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Satir, Sarp. "Modeling and optimization of capacitive micromachined ultrasonic transducers." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54303.
Повний текст джерелаGuldiken, Rasim Oytun. "Dual-electrode capacitive micromachined ultrasonic transducers for medical ultrasound applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31806.
Повний текст джерелаCommittee Chair: Degertekin, F. Levent; Committee Member: Benkeser, Paul; Committee Member: Berhelot, Yves; Committee Member: Brand, Oliver; Committee Member: Hesketh, Peter. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Choi, Hongsoo. "Fabrication, characterization and modeling of K₃₁ piezoelectric micromachined ultrasonic transducers (pMUTs)." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/h_choi_091007.pdf.
Повний текст джерелаDalakoti, Abhishek. "Optimization of PZT based thin films and piezoelectric micromachined ultrasonic transducers (pMUTs)." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/a%5Fdalakoti%5F083105.pdf.
Повний текст джерелаMylvaganam, Janani. "Characterization of medical piezoelectric ultrasound transducers using pulse echo methods." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9623.
Повний текст джерелаIn this thesis, a measurement set-up has been developed to characterize high frequency medical ultrasound transducers using a pulse echo set-up. This work is a continuation of an earlier project. The aim of this project is to improve the instrumentation to get more reliable, repeatable and consistent results. The transducer used in this project was a 20MHz annular array transducer with 8 elements. Parameters such as the electroacoustic transfer function and reflection coefficients of element 1 and 2 have been found for a sinusoidal burst excitation and a Gaussian excitation, to give examples for the estimation of these parameters. Developing the right instrumentation for the pulse echo set-up and transducer for pulse echo measurements has been emphasised, where a transducer holder and reflector have been constructed for characterization of elements 1-5. A cylindrical water resistant reflector with a curved top was designed giving certain degrees of freedom as opposed to the pure spherical reflector concerning positioning of the reflector with respect to the transducer. A slanted bottom was included in the design of the reflector causing reflections from the bottom to diffract and thus stopping these from interfering with the reflections of interest happening at the top of the reflector surface. A transducer holder was also designed and custom made for the transducer used in the project, where both mechanical and electrical considerations have been taken, as the holder makes alignment of the transducer with respect to the reflector easier and coaxial cables have been introduced to get more control over the signals going to and from the transducer array. Coaxial cables were chosen as these are easy to model, and have clear specifications in addition to having the property of shielding noise signals. Alignment of the transducer has been emphasised to make radiation into the focus of the reflector easier, although the design of the reflector also allows the reflector to be tilted in the allocation of its focus point. By taking detailed lateral scans of echoes received by the transducer using a robot, in addition to varying the distance between the transducer and the reflector with an increment of 0.2 mm, the reflection coefficients were found to be very sensitive to lateral positioning, and to some extent sensitive to axial positioning of the transducer with respect to the reflector. The elimination of propagation delay due to the signals travel in waterpath and electrical transmission and reception chain leading to the transducer ports has also been compensated for, as these delays will effect the complex values of the transfer function. The electrical propagation delay is eliminated by using a simulation program, and analysis of the time between two consecutive echoes is done in order to find the physical time delay in the water path the pulses travelled. The electro acoustic transfer function has also been found for element 1 and element 2, but with a much greater time delay than what was expected. An uncertainty budget of the obtained parameters has also been done to see the impact of laboratory equipment on the meaurements. Estimation schemes to obtain reflection coefficients and the electro acoustic transfer function have been developed, which are repeatable for further characterization for the whole transducer array. Existing MATLAB codes have been modified in simulations and some new codes have been written for analyzing measurement based estimation of transfer functions, reflection coefficients and effects of various filters on their characteristics. Different types of filters have been used on the recorded echo signals to eliminate noise from the estimated reflection coefficients. A better control of the parasitic inductances due to the non coaxial cables in the system should perhaps be evaluated, and for further characterization of the transducer, the mechanical admittance can also be found by using the estimated reflection coefficients and electro acoustic transfer function.
McLean, Jeffrey John. "Interdigital Capacitive Micromachined Ultrasonic Transducers for Microfluidic Applications." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7625.
Повний текст джерелаWygant, Ira Oaktree. "Three-dimensional ultrasound imaging using custom integrated electronics combined with capacitive micromachined ultrasonic transducers /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Повний текст джерелаKlemm, Markus. "Acoustic Simulation and Characterization of Capacitive Micromachined Ultrasonic Transducers (CMUT)." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-225933.
Повний текст джерелаCortes, Correales Daniel H. "Elastic guided wave dispersion in layered piezoelectric plates application to ultrasound transducers and acoustic sensors /." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10206.
Повний текст джерелаTitle from document title page. Document formatted into pages; contains vi, 84 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 79-84).
Devaraju, Vadivel Lewin Peter A. "Design, development and characterization of wideband polymer ultrasonic probes for medical ultrasound applications /." Philadelphia : Drexel University, 2003. http://dspace.library.drexel.edu/handle/1721.1/95.
Повний текст джерелаCezar, Mehmet. "Development And Microfabrication Of Capacitive Micromachinedultrasound Transducers With Diamond Membranes." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612958/index.pdf.
Повний текст джерелаm) and element spacing (250, 375 &mu
m). 1-D CMUT array devices can be used for focusing ultrasound applications. The electronic circuit for 1-D CMUT devices with diamond membranes was designed and implemented on PCB for the ultrasound focusing experiment. This electronic circuit generates continuous or burst AC signals of ±
15 V with different and adjustable phase shifting options at 3 MHz frequency. 16 elements of 72 &mu
m 1-D CMUT array were successfully tested. Fully functional 7 elements of 1-D CMUT array are focused at an axial distance of 5.81 mm on the normal to the CMUT center plane. The CMUT array was excited using 10 Vp&minus
p with 10 cycles sinusoidal signals at 3 MHz. The microfabrication process and focusing ultrasound of 1-D CMUT devices with diamond membranes are done successfully in this thesis.
Thongchai, Tanikan. "Fabrication of lead free and lead based 1-3 piezoelectric composites for high frequency ultrasound transducers." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8041/.
Повний текст джерелаGhasemi, Negareh. "Improving ultrasound excitation systems using a flexible power supply with adjustable voltage and frequency to drive piezoelectric transducers." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61091/1/Negareh_Ghasemi_Thesis.pdf.
Повний текст джерелаNascimento, Valéria Monteiro do 1974. "Simulação do campo acústico de transdutores ultrassônicos de alta frequência do tipo array anular com e sem espaçamento entre anéis." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261168.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Para observar o efeito no campo acústico dos diversos parâmetros de configuração do projeto de um transdutor ultrassônico, foram simuladas várias configurações de transdutor de alta frequência (5 a 50 MHz), tipo array anular, com kerf e kerfless, de cerâmica PZT-5H e de filme de PVDF. Transdutores com configurações de três, quatro, cinco e seis anéis, em que os anéis possuíam a mesma largura foram simulados com elemento ativo de cerâmica. E transdutores com cinco, seis, sete, oito e dez anéis de mesma área, com separação física entre os elementos (kerf) e sem separação física entre os elementos (kerfless) foram simulados com elementos piezoelétricos de cerâmica PZT-5H e filme de PVDF. Também foram testados materiais de diferentes impedâncias acústicas nas camadas de retaguarda (epóxi, epóxi e Araldite, ferro, tungstênio, alumina e madeira), foram usadas diversas funções de excitação dos elementos piezoelétricos (Blackman, Wavelet, Gauss, Seno, Step) em frequências variadas, além de se acionar os diversos elementos anelares isoladamente, em grupos e com atraso temporal. O objetivo das simulações realizadas foi determinar a melhor configuração de um transdutor array anular, quanto ao número de anéis, espaçamento entre eles e necessidade ou não de separação física entre os elementos, levando-se em conta a complexidade de construção e as características do campo acústico gerado. Para isso, os parâmetros observados no campo acústico foram à amplitude do pico, a amplitude média de pressão, a profundidade do campo, a colimação do feixe principal e a presença de lóbulos laterais. Outros parâmetros observados foram à tensão e a carga nos elementos. Os resultados obtidos nas simulações dos transdutores arrays circulares, feitas com o programa PZFlex®, foram processados no Matlab® para visualização do campo acústico e extração de parâmetros. As funções de transferência do sinal de excitação e da resposta à estimulação foram calculadas com os dados obtidos. O transdutor kerfless foi simulado no PZFlex® e seus resultados processados no Matlab®, para comparar com os resultados do transdutor com kerf de mesma configuração. Os resultados das simulações mostraram que o campo acústico neste tipo de transdutor, array anular, tem a região de campo distante começando bem próximo à face do transdutor. A camada de retaguarda de epóxi e Araldite® apresentaram valores mais elevados de amplitude do campo acústico. A função de excitação foi Wavelet na frequência de 30 MHz devido às restrições da relação diâmetro / espessura da cerâmica PZT-5H. O transdutor kerfless apresentou um campo acústico com as mesmas características do transdutor com kerf, com a vantagem de sua construção ser mais simples
Abstract: In order to observe the effect of ultrasound transducers parameters configurations in an acoustic field, simulations were made in some different configuration of an annular array ultrasound transducer in high frequency (5 to 50 MHz), kerf and kerfless, with active element of PZT - 5H ceramic or PVDF. The transducers configurations simulated were three, four, five and six annulus, with the same width, and the active element was PZT-5H. And transducers with five, six, seven, eight and ten annulus, with the same area, with and without physical separation between the elements had been simulated with active element of PZT-5H ceramics or PVDF. The materials of backing layer (epoxy, epoxy and Araldite, iron, tungsten, alumina and wood dust) with different impedance were also be tested, and a variety of excited functions (Blackman, Wavelet, Gauss, Sine, Step), in different frequencies, and also with time delay in active elements. The objective of this simulation was to find out the better configuration of an annular array ultrasound transducer in high frequency, the number of annulus, spacing between them, the area, the transducer is kerf or kerfless, considering the build complexity and the characteristics of acoustic field. To do this, the peak amplitude, the depth and the average amplitude of the acoustic field was measured. The charge and the voltage in the elements were also observed. The results obtained in simulations in PZFlex® software were run in Matlab® to visualize the acoustic field and to extract parameter. The ultrasound kerfless transducer was simulated in PZFlex® and the data obtained runs in Matlab®, the results were compared with the results of a transducer with kerf in the same configuration. The simulation results showed that the acoustic field of this kind of transducer has Fraunhofer zone began near the transducer's face. The backing layer with epoxy and Araldite® showed high amplitude of acoustic field. The frequency 30 MHz was choice due to diameter/thickness relations. The excitation function was wavelet, as this present high values response in acoustic field. Kerfless transducer showed acoustic field characteristics the same as the kerf transducers, with the advantage of a simple construction
Doutorado
Engenharia Biomedica
Doutora em Engenharia Elétrica
Zanella, Fabio Pieroni. "Sistema multicanal de geração e recepção de ondas ultra-sonicas para transdutor matricial linear." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258954.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: O ultra-som na medicina tem passado por enorme evolução nas últimas décadas e ocupado posição de destaque cada vez maior como ferramenta para terapia e diagnóstico. Isso é devido principalmente ao fato de que os equipamentos de diagnóstico por ultra-som são de relativo baixo custo, o ultra-som é uma radiação não-ionizante e permite realização de exame por método não-invasivo e as imagens são geradas e visualizadas em tempo real. Na geração de imagens deste tipo, é comum a utilização de transdutores matriciais. Entretanto, o Brasil apresenta defasagem tecnológica com respeito à construção destes transdutores e à eletrônica envolvida em sua operação. O objetivo deste trabalho consistiu no desenvolvimento de circuitos eletrônicos com 12 canais de geração e de recepção de ondas ultra-sônicas para operação com transdutor matricial linear. O sistema é capaz de excitar transdutores piezoelétricos e receber ecos ultra-sônicos na faixa de 0,5 a 30 MHz e tem seus circuitos de recepção protegidos contra a alta tensão dos pulsos gerados para a excitação do transdutor. Os disparos dos elementos do transdutor e o tempo de corte dos sinais nos circuitos de recepção, para evitar receber sinais indesejáveis referentes ao período inicial de oscilação do transdutor, são controlados via circuito com microcontrolador PIC 16F877 que, juntamente com o programa de controle, foram desenvolvidos para conectar o sistema a um microcomputador. Os 12 canais foram caracterizados eletricamente e verificou-se seu funcionamento utilizando um transdutor piezoelétrico linear de 12 elementos com 1 MHz de freqüência central, especialmente desenvolvido para este trabalho. Os resultados mostraram que o sistema funciona adequadamente, gerando imagem de um phantom construído em nosso laboratório
Abstract: Ultrasound in medicine has gone through great evolution in the last few decades and has occupied important position as a tool for therapy and diagnosis. This is due to the ultrasound equipment be of relatively low-cost, ultrasound is a non-ionizing radiation, is a non-invasive imaging method, and the images are created and seen in real time. It is common the use of transducer arrays in order to generate this kind of image. There is a lack of know how in Brazil relative to the construction of these transducers and the involved electronics in their operation. The objective of this work was the development of a multi-purpose 12 channel pulser/receiver electronic circuitry to operate with linear transducer arrays. The system is able to fire ultrasound piezoelectric transducers and to receive ultrasound echo signals in the range 0.5-30 MHz. The system has reception circuits with protection against high voltage pulses. The firing of transducer elements and cutting time of the reception circuits, to avoid unwanted signals of natural initial transducer oscillations, can be controlled via PIC 16F877 hardware and software designed to connect the system to a microcomputer. The electrical characteristics of the 12 channel pulser/receiver and its use in firing a specially constructed 1 MHz 12 element PZT transducer array has been carried out and the images of a specially constructed phantom showed that it can be used in laboratory conditions
Mestrado
Engenharia Biomedica
Mestre em Engenharia Elétrica
Bakhtiari, Nejad Marjan. "Dynamics of Multi-functional Acoustic Holograms in Contactless Ultrasonic Energy Transfer Systems." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/102414.
Повний текст джерелаDoctor of Philosophy
This dissertation presents several techniques to enhance the wireless transfer of ultrasonic energy in which the sound wave is generated by an acoustic source or transmitter, transferred through an acoustic medium such as water or human tissue to a sensor or receiver. The receiver transducer then converts the vibrational energy into electricity and delivers to an electrical load in which the electrical power output from the system can be determined. The first enhancement technique presented in this dissertation is using a pre-designed and simple structured plate called an acoustic hologram in conjunction with a transmitter transducer to arbitrarily pattern and shape ultrasound fields at a particular distance from the hologram mounted on the transmitter. The desired wavefront such as single or multi-focal pressure fields or an arbitrary image such as a VT image pattern can simply be encoded in the thickness profile of this hologram plate by removing some of the hologram material based on the desired shape. When the sound wave from the transmitter passes this structured plate, it is locally delayed in proportion to the hologram thickness due to the different speed of sound in the hologram material compared to water. In this dissertation, various hologram types are designed numerically to implement in the ultrasonic power transfer (UPT) systems for powering receivers located at the predetermined focal points more significantly and finally, their functionality and performances are verified in several experiments. Current UPT systems suffer from significant acoustic losses through the transmission from a transmitter to an acoustic medium and then to a receiver due to the different acoustic impedance (defined as the product of density and sound speed) between the medium and transducers material, which reflects most of the incident pressure wave at the boundary layers. The second enhancement technology addressed in this dissertation is using intermediate materials, called acoustic impedance matching layers, bonded to the front side of the transmitter and receiver face to alleviate the acoustic impedance mismatch. Experiments are performed to identify the input acoustic pressure from a transmitter to a receiver. Using a two-layer matching structure, significant enhancements are observed in terms of the receiver's electrical power output. A design platform is also developed that can facilitate the construction of high-fidelity acoustically matched transducers, that is, the material layers' selection and determination of their thicknesses. Furthermore, this dissertation presents a numerical analysis for the dynamical motions of a microbubble exposed to a high-intensity focused ultrasound (HIFU) field, which entails the problem of several biomedical ultrasound applications such as microbubble-mediated ultrasound therapy or targeted drug delivery. Finally, an enhancement technique involving the design and use of acoustic holograms in microfluidic channels is addressed which opens the door of acoustic patterning in particle and cell sorting for medical ultrasound systems.
Silva, Emilio Carlos Nelli. "Modelagem vibracional de transdutores de ultra-som piezoelétricos pelo método de elementos finitos." Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/3/3132/tde-11072017-091843/.
Повний текст джерелаThe theoretical basis of piezoelectric finite element method (FEM), and its application in piezoelectric ultrasonic transducer modelling is presented. Among these applications we have the calculation of resonance and antiresonance frequencies, vibration modes, piezoelectric coupling coefficient, admittance curve and transient analysis of piezoelectric structure excited by a short pulse. By means of piezoelectric FEM the influence of variation of piezoelectric constant with radius is analysed. It is discussed three kind of functions (linear, cosinoidal and Gaussian). This technique is called apodization. The acoustic filed generated by the transducer operating in continuous wave (CW) was calculated by using FEM applied to acoustic, considering the fluid-structure coupling. The study of wave propagation in liquids is started by using FEM, analyzing the waves generated by a plane piston in contact with the fluid, excited by a short pulse. For each case discussed above, all boundary conditions and hypothesis assumed in the construction of finite element models are discussed. Although the models considered are circular transducers, the concepts acquired can be expanded to other geometries. The vibrational modes were visualized by means of a laser interferometry technique (ESPI), and the admittance curves were measured by using an impedometer. These results were compared with the FEM results, and the models precision was discussed.
Boulmé, Audren. "Conception et caractérisation de sondes cMUT large bande pour l'imagerie conventionnelle et l'évaluation du tissu osseux." Thesis, Tours, 2013. http://www.theses.fr/2013TOUR3319/document.
Повний текст джерелаFollowing recent advances, the capacitive Micromachined Ultrasound Transducers (cMUT) technology seems to be a good alternative to the piezoelectric technology. For specific applications, the requirements and specifications of the probe are sometimes difficult to obtain with the traditional PZT technology. The cMUT technology, with both large bandwidth and angular directivity, can be an interesting way to overcome these limitations. This PhD has been carried out in this context, in a laboratory which has nearly 10 years of experience in the field of cMUT technology. The originality of the work sustained in this PhD is that it covers the cMUT technology, from general aspects dealing of modeling and characterization up to a complete example of cMUT-based probe applied to the assessment of cortical bone. Fast and accurate modeling tools, based on periodicity conditions, have been developed. Several models have been proposed to match the modeling strategy to the topology of the cMUT array : isolated cell, columns of cells, 2-D matrix of cells and array element. These models have been used to analyze the cMUT array behavior and to understand how mutual couplings between cMUTs impact the response of one element. Origins of the baffle effect, well-known as a recurrent problem in cMUT probe, have been explained using an original method based on the normal mode decomposition of the radiated pressure field. Thus, solutions have been identified and tested to optimize the cMUT frequency response, i.e. to increase the bandwidth, and to suppress parasitic disturbances linked to baffle effect in the electroacoustic response. The development of a dedicated cMUT array for the assessment of bone tissue is accurately detailed in the manuscript, including description of the design rules, fabrication steps and packaging procedure. An original characterization work has been carried out in order to check the device homogeneity, first from cell to cell and then from element to element. Finally, a comparison with a PZT probe with the same topology has been performed on bone mimicking phantom. Nice results has been obtained, showing that cMUT probe allows detecting higher number of guided modes in the cortical shell, and consequently, improving the cortical bone assessment
Chou, Derrick Ren-yu. "Piezoelectric Micromachined Ultrasound Transducers for Medical Imaging." Diss., 2011. http://hdl.handle.net/10161/4978.
Повний текст джерелаPiezoelectric micromachined ultrasound transducer (pMUT) two-dimensional (2D) arrays have been proposed as an alternative to conventional bulk-PZT thickness-mode transducers for high frequency, forward-looking, catheter-based ultrasound imaging of the cardiovascular system. The appeal of pMUTs is based on several key advantages over conventional transducer technologies, including high operational frequencies, small element size, and low cost due to their microelectromechanical system (MEMS) silicon-based fabrication. While previous studies have demonstrated acoustic performance characteristics suitable for ultrasound image formation, pulse-echo B-mode imaging of tissue and tissue-like phantoms using 2D pMUT arrays small enough for forward-looking catheter-based applications have been demonstrated only at Duke University by Dausch et al.
Having demonstrated the suitability of 2D pMUT arrays for tissue imaging, an important step is to demonstrate effective design control. The frequency of operation is a fundamental component of transducer design. Previous modeling efforts for pMUT vibration have used classical/Kirchoff thin plate theory (CPT) or Mindlin thick plate theory, however pMUTs with geometric dimensions similar to those explored here, have not been modeled with experimental comparison to physical devices.
It is hypothesized that the frequency of vibration of pMUTs can be predictively modeled based on experimental data from various pMUT configurations. Experimental frequency results were acquired and used to develop an empirical model based on a modified Mindlin thick plate theory. This dissertation presents the development of the frequency design theory culminating in a set of predictive design equations for the frequency of vibration of 2D pMUT arrays aimed at improving their use in high-frequency, forward-looking, catheter-based ultrasound imaging applications.
Dissertation
Dangi, Ajay. "Piezoelectric Micromachined Ultrasound Transducers : From Design to Applications." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/3737.
Повний текст джерелаDangi, Ajay. "Piezoelectric Micromachined Ultrasound Transducers : From Design to Applications." Thesis, 2016. http://etd.iisc.ernet.in/2005/3737.
Повний текст джерелаGupta, Harshvardhan. "Development of High-Performance Piezoelectric Micromachined Transducers for Near Ultrasound." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/6109.
Повний текст джерелаAhmad, Babar. "Design and Development of Capacitive Micromachined Ultrasonic Transducers." Thesis, 2012. http://etd.iisc.ac.in/handle/2005/3164.
Повний текст джерелаAhmad, Babar. "Design and Development of Capacitive Micromachined Ultrasonic Transducers." Thesis, 2012. http://hdl.handle.net/2005/3164.
Повний текст джерелаRoy, Kaustav. "Development of Piezoelectric Ultrasound Transducers for Novel Applications." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5698.
Повний текст джерелаMinistry of Education, National Institutes of Health
Logan, Andrew Stephan. "The Design, Fabrication and Characterization of Capacitive Micromachined Ultrasonic Transducers for Imaging Applications." Thesis, 2010. http://hdl.handle.net/10012/5583.
Повний текст джерелаHsien, Chang Chien, and 張建信. "PSpice Modeling of Piezoelectric Polymer Films with Application on Ultrasound Transducers." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/38255214740300616737.
Повний текст джерела國立成功大學
機械工程學系
88
Piezoelectric Polymer is suitable to fabricate immersion-type ultrasound transducers because of its low acoustic impedance, low acoustic quality factor and low dielectric constant. Low acoustic impedance can reduce reflection as ultrasound passing through material interfaces;low acoustic quality factor makes it possible to accomplish a broad-band transducer. Since the piezoelectric polymer has these advantages, this thesis will investigate several important factors that affect the performance of piezoelectric polymer transducers using Spice circuit simulation. The modeling of a piezoelectric acoustic transducer consists of two parts, namely acoustic part and electric part. Once the Spice simulation of both features of a piezoelectric transducer is established, one can easily analyze the ultrasound measurement system just by adding electric elements into the simulation circuit file. For a PVDF transducer studied in this work, it is found that, thickness of electrodes, elastic properties of backing materials, shapes of electric pulses, and the connecting circuits of transducers all affect transducers’ performance such as amplitude of signal, central frequency, and bandwidth. Finally, to obtain a high-frequency PVDF transducer and ultrasound system, the simulation results indicate that the following two requirements are important. 1. PVDF film thickness and selection of backing materials are the key issues for making high frequency PVDF transducers. 2. Connecting circuit with the transducer should match to 50Ω.
Chen, Guan Lin, and 陳冠霖. "Piezoelectric Polymer Micromachined Acoustic Transducers and Their Applications to Rapid Screening of Drug Residue in Foods." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ws4rzr.
Повний текст джерела國立清華大學
動力機械工程學系
105
In recent years, people pay more attention to food safety. Traditional detection technology is expensive, complicated and time-consuming, so that it is impossible to do the real-time and on-site detection for the irregular additives in food samples. This study further investigate and improve the droplet-based piezoelectric polymer deposition. In addition, the deposited piezoelectric polymer deivces are integrated on a biochip for rapid detection of drug residue in foods. First, we changed the wire width of electrode to design and choose different area ratio of P(VDF-TrFE). In the electrodeposition process, we discussed the optimization parameter, including electrodeposition time, volume of droplet, supplying voltage, and the pre-treatment of relative humidity. In the examination of acoustic property, the maximum output power was 86.31 μW (10 kHz). Compare of past study, the signal strengthen was enhanced by 62 % (10 kHz), the output power was enhanced by 37 %, the efficiency was enhanced by 220 %. In the property of acoustic transceiver, the signal coefficient of variation was reduced to 0.38 % from 17.79 % by the pre-tunable treatment. The developed acoustic transceiver was applied to the detection of animal drugs residue in meat samples after the optimization process and pre-tunable treatment. The detection frequency was 10 kHz, and the target drugs were ractopamine、benzylpenicillin、doxycycline. The response, including fluid disturbance and steady tim) was 80 sec, and the SNR of steady signal was up to 29.03 dB. Linear range was 0 ~ 100 ppb, and sensitivity was up to 2.4 mV/ppb and the detection limit was 2.06 ppb (3 dB). Finally, the acoustic transceiver was integrated with MIP films on microfluidic chip, and 20 ppb pork sample was applied to our chip for drugs residue detection. The detection result was up to 23.7±1.15 ppb. The detection time was 4 min, including fluid operation and dynamic signal measurement. In this study, the developed high-sensitivity piezoelectric acoustic transceiver presented the advantages of low cost, simple steps and high integration. Besides the drugs residue detection, it also was applied as others biosensor in the future.
Klemm, Markus. "Acoustic Simulation and Characterization of Capacitive Micromachined Ultrasonic Transducers (CMUT)." Doctoral thesis, 2016. https://tud.qucosa.de/id/qucosa%3A30359.
Повний текст джерелаGiannelli, Pietro. "A Testbench System for Structural Health Monitoring with Guided-Wave Ultrasound." Doctoral thesis, 2018. http://hdl.handle.net/2158/1125295.
Повний текст джерелаYi-HongZou and 鄒乙弘. "Development of the Li-Doped Potassium Sodium Niobate Piezoelectric Ceramics with High Electromechanical Coupling Coefficient and Applied to Single-Element Ultrasound Transducers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/03209147188193363951.
Повний текст джерела國立成功大學
電機工程學系碩博士班
101
In this study, the development of lead-free (1-x)(Na0.535K0.48)NbO3-xLiNbO3 (NKLN) ceramics were investigated and the phase transition behavior of material, sintering temperature and poling condition were discussed. In NKLN ceramics, it was observed that the morphotropic phase boundary (MPB) not only contented the orthorhombic and tetragonal phases, but also had the formation of monoclinic phase. The best piezoelectric properties of NKLN ceramics with kp = 42%、kt = 52% were obtained at x = 0.05. In 0.95NKN-0.05LN ceramics, the sintering temperature was reduced from 1050oC to 900oC and the excellent piezoelectric properties were obtained under sintering at 950oC. Moreover, the 0.95NKN-0.05LN ceramics sintered at 950oC for different soak times was also investigated. The maximum values of kp (48%) and kt (52 %) were obtained at the optimum soak time of 4 h. In the present study, the electric properties of ceramics were significantly by the poling conditions, including poling temperature and poling electric field. The optimum poling conditions obtained were under the poling temperature of 90oC and poling electric field of 3 kV/mm. Based on the properties of ceramics above, the ceramics with high kp and kt values were chose for fabrication of single-element ultrasound transducers. The acoustic impedances of the ceramics and backing layer were calculated. The pulse/echo response of the ultrasound transducers fabricated using the (Na0.5K0.5)NbO3 and 0.95(Na0.535K0.48)NbO3- 0.05LiNbO3 ceramics were examined and the performances of these two ultrasound transducers were compared. Effects of piezoelectric properties of ceramics on the performances of ultrasound transducer were also investigated.
Fangueiro, Gil Mauro Cruz. "Desenvolvimento de sensor acústico para medição de corrente marítima." Master's thesis, 2019. http://hdl.handle.net/1822/69796.
Повний текст джерелаO objetivo deste trabalho é desenvolver um sensor acústico capaz de medir correntes marítimas. Este projeto surge da necessidade de recolher alguns dados de interesse marítimo com o objetivo de criar modelos de funcionamento dos ecossistemas. Neste projeto pretende-se colocar vários sensores georreferenciados, a diferentes profundidades, a fazer medições e a armazenar os dados respetivos. Este sensor será responsável por medir a velocidade da água que flui num determinado nó do sistema. Este deverá ser capaz de medir a intensidade da corrente e a direção independentemente da sua posição no espaço, necessitando por isso de um magnetómetro (bússola digital) para utilizar o norte geográfico como referência. O sensor de corrente marítima que é apresentado utiliza transdutores piezoelétricos ultrassónicos pretendendo com isso tornar o sistema mais fiável e com maior robustez devido à ausência de partes móveis. A propriedade dos ultrassons explorada neste trabalho para obtenção da velocidade da corrente é o tempo de voo. O tempo de voo é o tempo que um determinado sinal demora a propagar-se num determinado meio entre dois pontos. No desenvolvimento do sensor será estudado o formato da estrutura, a posição e a orientação dos transdutores, de forma a melhorar a qualidade das medições em diferentes condições. Tal deverá ter em conta a robustez, dimensões razoáveis e evitar fenómenos de turbulência no volume de água a ser medido. O processamento dos sinais enviados e recebidos pelos transdutores será executado por um circuito integrado capaz de executar rotinas de medição de tempo de voo e de temperatura. Esse circuito integrado irá comunicar com um microcontrolador que irá interpretar os tempos de voo e converter na velocidade do fluido. Para além da comunicação com este circuito integrado, o microcontrolador, terá que comunicar com um relógio de tempo real, para obtenção de uma referência temporal, com um cartão de memória, para armazenamento de dados num ficheiro e com um magnetómetro, para obter uma referência de orientação ao norte geográfico já que o sensor não estará fixo. Com vários sensores destes é possível entender fenómenos de transporte à escala costeira, graças aos dados que é possível obter com um instrumento de medição desta escala.
The objective of this work is to develop an acoustic sensor capable of measuring sea currents. This project arises from the need to collect some data of maritime interest with the aim of creating models for the functioning of ecosystems. In this project, we intend to place several georeferenced sensors at different depths to make measurements and store the respective data. This sensor will be responsible for measuring the velocity of the water flowing in a particular node of the system. It should be able to measure the intensity of the current and direction independently of its position in space, thus necessitating a magnetometer (digital compass) to establish geographic north as a reference. The marine current sensor which is shown utilizes ultrasonic piezoelectric transducers in order to make the system more reliable and more robust due to the absence of moving parts. The property of the ultrasound explored in this work to obtain the velocity of the current is the flight time. Flight time is the time that a given signal takes to propagate in a certain medium between two points. In the development of the sensor will be studied the structure format, the position and the orientation of the transducers, in order to improve the quality of the measurements under different conditions. This should take into account the robustness, reasonable dimensions and avoid phenomena of turbulence in the volume of water to be measured. The processing of the signals sent and received by the transducers will be performed by an integrated circuit capable of performing flight time and temperature measurement routines. This integrated circuit will communicate with a microcontroller that will interpret flight times and convert to fluid velocity. In addition to communicating with this integrated circuit, the microcontroller must communicate with a real-time clock, to obtain a time reference, with a memory card, to store data in a file and with a magnetometer, to obtain a reference geographic north since the sensor will not be static. With several sensors of these it is possible to understand transport phenomena to the scale of the coast, thanks to the data that can be obtained with a measurement instrument of this scale.