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Sang-Gook Kim and Charles G. Sodini. Smyth, Katherine Marie Massachusetts Institute of Technology. Department of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering 2017-05-11T19:56:44Z 2017-05-11T19:56:44Z 2017 2017 http://hdl.handle.net/1721.1/108938 986242409 Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 175-184). Next generation medical imaging technology hinges on the development of cost effective and array compatible transducers making piezoelectric micro-machined ultrasonic transducers (pMUTs) an attractive alternative to the current bulk piezoelectric technology. This thesis aims to realize pMUT potential starting with the development of an effective single cell model that is further scaled to optimize multi-cell elements in a 1D array. In the first half of this work, a transverse mode, lead zirconate titanate (PZT) pMUT plate cell is fabricated using common micro-fabrication techniques and a PZT sol-gel deposition process. Through derivation using a novel Greens function solution technique, an equivalent circuit model with explicitly defined lumped parameters is presented and validated through electrical impedance measurements of fabricated devices and finite element modeling. The equivalent circuit is a crucial design tool as transducer performance metrics, including experimentally validated acoustic domain values, are shown to be defined directly from the lumped parameters. In the second half, figures of merit are identified from these performance metrics and an expanded multi-cell model is employed to strategically target improvements in both bandwidth and coupling while maintaining high pressure output. The resulting, optimized multicell elements in a 1D array are fabricated via a commercially viable, wafer-scale manufacturing process including a novel PZT dry etch. A top-down fabrication approach facilitates achievement of the largest active area of a multi-cell pMUT to date consisting of over 1000 cells in a 200pm x 4mm element footprint, and more substantially, results in the highest electromechanical coupling recorded for a pMUT to date measured at 9 ± 1.4% per element. by Katherine Marie Smyth. Ph.D. 184 pages eng Massachusetts Institute of Technology MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 Mechanical Engineering. Piezoelectric micro-machined ultrasonic transducers for medical imaging PMUTs for medical imaging Thesis application/pdf Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="82ab03ff-326e-47d4-86e1-3878ed48312e"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Piezoelectric micro-machined ultrasonic transducers for medical imaging</Title> <Subtitle>PMUTs for medical imaging</Subtitle> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2017</PublicationDate> <Authors> <Author> <DisplayName>Smyth, Katherine Marie</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Mechanical Engineering.</Keyword> <Abstract>Next generation medical imaging technology hinges on the development of cost effective and array compatible transducers making piezoelectric micro-machined ultrasonic transducers (pMUTs) an attractive alternative to the current bulk piezoelectric technology. This thesis aims to realize pMUT potential starting with the development of an effective single cell model that is further scaled to optimize multi-cell elements in a 1D array. In the first half of this work, a transverse mode, lead zirconate titanate (PZT) pMUT plate cell is fabricated using common micro-fabrication techniques and a PZT sol-gel deposition process. Through derivation using a novel Greens function solution technique, an equivalent circuit model with explicitly defined lumped parameters is presented and validated through electrical impedance measurements of fabricated devices and finite element modeling. The equivalent circuit is a crucial design tool as transducer performance metrics, including experimentally validated acoustic domain values, are shown to be defined directly from the lumped parameters. In the second half, figures of merit are identified from these performance metrics and an expanded multi-cell model is employed to strategically target improvements in both bandwidth and coupling while maintaining high pressure output. The resulting, optimized multicell elements in a 1D array are fabricated via a commercially viable, wafer-scale manufacturing process including a novel PZT dry etch. A top-down fabrication approach facilitates achievement of the largest active area of a multi-cell pMUT to date consisting of over 1000 cells in a 200pm x 4mm element footprint, and more substantially, results in the highest electromechanical coupling recorded for a pMUT to date measured at 9 ± 1.4% per element.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>