Design, fabrication and operation of a very high intensity CMUT transmit array for beam steering applications

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buir.advisorKöymen, Hayrettin
dc.contributor.authorKhan, Talha Masood
dc.date.accessioned2020-12-29T13:42:47Z
dc.date.available2020-12-29T13:42:47Z
dc.date.copyright2020-12
dc.date.issued2020-12
dc.date.submitted2020-12-28
dc.departmentGraduate Program in Materials Science and Nanotechnologyen_US
dc.descriptionCataloged from PDF version of article.en_US
dc.descriptionThesis (Ph.D.): Bilkent University, Department of Materials Science and Nanotechnology, İhsan Doğramacı Bilkent University, 2020.en_US
dc.descriptionIncludes bibliographical references (leaves 61-69)en_US
dc.description.abstractSeveral studies have reported airborne ultrasound transmission systems focused on achieving beamforming. However, beam steering and beamforming for capacitive micromachined ultrasonic transducers (CMUTs) at high intensity remains to be accomplished. CMUTs, like other ultrasonic transducers, incorporate a loss mechanism to obtain a wide bandwidth. They are restricted to a limited amount of plate swing due to the gap between the radiating plate and the bottom electrode, along with a high dc bias operation. CMUTs can be designed to produce high-intensity ultrasound by employing an unbiased operation. This mode of operation allows the plate to swing the entire gap without collapsing, thus enabling higher intensity. In this study, we use an equivalent circuit-based model to design unbiased CMUT arrays driven at half the mechanical frequency. This model is cross verified using finite element analysis (FEA). CMUT arrays are produced in multiple configurations using a customized microfabrication process that involves anodic wafer bonding, a single lithographic mask, and a shadow mask. We use impedance measurements to characterize the microfabricated devices. We experimentally obtained the highest reported intensity using a microfabricated 2×2 CMUT array driven at resonance in a pulsed configuration. This array is also capable of beam steering and beamforming at a high intensity such that it can steer the entire half-space. The beam obtained from the array is in excellent agreement with the theoretical predictions. The amplitude and phase compensation for the devices remain constant that makes these arrays attractive for applications involving park assist, gesture recognition, and tactile displays.en_US
dc.description.degreePh.D.en_US
dc.description.statementofresponsibilityby Talha Masood Khanen_US
dc.format.extentxv, 97 leaves : color illustrations, charts ; 30 cm.en_US
dc.identifier.itemidB124989
dc.identifier.urihttp://hdl.handle.net/11693/54860
dc.language.isoEnglishen_US
dc.publisherBilkent Universityen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectAirborne ultrasounden_US
dc.subjectCapacitive micromachined ultrasonic transducersen_US
dc.subjectCMUTen_US
dc.subjectTransducer arrayen_US
dc.subjectHigh Intensityen_US
dc.subjectBeam steeringen_US
dc.subjectMEMSen_US
dc.subjectUnbiased operationen_US
dc.subjectHalf frequency drivenen_US
dc.subjectMutual radiation impedanceen_US
dc.subjectLumped element modelen_US
dc.subjectLarge signal equivalent circuit modelen_US
dc.subjectArrayen_US
dc.subjectMicrofabricationen_US
dc.titleDesign, fabrication and operation of a very high intensity CMUT transmit array for beam steering applicationsen_US
dc.title.alternativeYüksek yoğunluklu CMUT iletim dizilerinin ışın yönlendirme uygulamaları için tasarımı, üretimi ve kullanımıen_US
dc.typeThesisen_US

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