Design and implementation of capacitive micromachined ultrasonic transducers for high power

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buir.contributor.authorAtalar, Abdullah
buir.contributor.authorKöymen, Hayrettin
buir.contributor.orcidAtalar, Abdullah|0000-0002-1903-1240
dc.citation.epage1015en_US
dc.citation.spage1012en_US
dc.contributor.authorYamaner F.Y.en_US
dc.contributor.authorÖlçüm, Selimen_US
dc.contributor.authorBozkurt, A.en_US
dc.contributor.authorKöymen, Hayrettinen_US
dc.contributor.authorAtalar, Abdullahen_US
dc.coverage.spatialOrlando, FL, USAen_US
dc.date.accessioned2016-02-08T12:16:35Z
dc.date.available2016-02-08T12:16:35Z
dc.date.issued2011en_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.descriptionDate of Conference: 18-21 Oct. 2011en_US
dc.description.abstractCapacitive micromachined ultrasonic transducers (CMUTs) have a strong potential to compete piezoelectric transducers in high power applications. In a CMUT, obtaining high port pressure competes with high particle velocity: a small gap is required for high electrostatic force while particle displacement is limited by the gap height. On the other hand, it is shown in [1] that CMUT array exhibits radiation impedance maxima over a relatively narrow frequency band. In this paper, we describe a design approach in which CMUT array elements resonate at the frequency of maximum impedance and have gap heights such that the generated electrostatic force in uncollapsed mode, can sustain particle displacement peak amplitude up to the gap height. The CMUT parameters are optimized for around 3 MHz of operation, using both a SPICE model and FEM. The optimized parameters require a thick membrane and low gap heights to get maximum displacement without collapsing membrane during the operation. We used anodic bonding process to fabricate CMUT arrays. A conductive 100 μm silicon wafer is bonded to a glass wafer. Before the bonding process, the silicon wafer is thermally oxidized to create an insulating layer which prevents break down in the operation. Then, the cavities are formed on the insulating layer by a wet etch. The gap height is set to 100 nm. Meanwhile, the glass wafer is dry etched by 120 nm and the etched area is filled by gold evaporation to create the bottom electrodes. The wafers are dipped into piranha solution and bonding process is done afterwards. The fabricated CMUTs are tested in an oil tank. To eliminate the DC voltage which may cause charging problem in the operation, we tried to drive the CMUT array with large continuous wave signals at half of the operating frequency. We observed 1MPa peak to peak pressure with -23 dB second harmonic at the surface of the array (Fig. 1). The proposed design further extends the operation of CMUTs. Observing low harmonic distortions at high output pressure levels, without any charging problem, make CMUT a big candidate for high power applications. © 2011 IEEE.en_US
dc.identifier.doi10.1109/ULTSYM.2011.6293596en_US
dc.identifier.urihttp://hdl.handle.net/11693/28291
dc.language.isoEnglishen_US
dc.publisherIEEEen_US
dc.relation.isversionofhttp://dx.doi.org/10.1109/ULTSYM.2011.6293596en_US
dc.source.title2011 IEEE International Ultrasonics Symposiumen_US
dc.subjectIntegrated circuit modelingen_US
dc.subjectImpedanceen_US
dc.subjectArraysen_US
dc.subjectSiliconen_US
dc.subjectTransducersen_US
dc.subjectSurface impedanceen_US
dc.subjectResonant frequencyen_US
dc.titleDesign and implementation of capacitive micromachined ultrasonic transducers for high poweren_US
dc.typeConference Paperen_US

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