Show simple item record

dc.contributor.advisorDegertekin, F. Levent
dc.contributor.authorArkan, Evren Fatih
dc.date.accessioned2021-06-10T13:54:03Z
dc.date.available2021-06-10T13:54:03Z
dc.date.created2020-05
dc.date.issued2020-04-20
dc.date.submittedMay 2020
dc.identifier.urihttp://hdl.handle.net/1853/64601
dc.description.abstractHigh frequency ultrasound imaging is utilized in a broad range of applications from intravascular imaging to small animal imaging for preclinical studies. Capacitive micromachined ultrasonic transducers (CMUTs) possess multiple preferable characteristics for high frequency imaging systems, such as simpler fabrication methods, simpler integration to electronics, and greater variety of array geometries. Adequate performance and optimization of CMUT based systems require a comprehensive analysis of multiple design parameters. This research utilizes a nonlinear lumped model, capable of simulating the pressure output, electrical input-output, and echo response to a planar reflector of CMUT arrays with arbitrary membrane shape and array geometry, to determine the performance limitations of high frequency CMUT arrays and the effect of different design parameters on its performance. Receiver performance is analyzed through parameters extracted from simulations, namely, thermal mechanical current noise, plane wave pressure sensitivity, and pressure noise spectrum. Transmitter performance is analyzed through pressure output simulation, and the overall performance is analyzed through the simulated pulse-echo response from a perfect planar reflector and the thermal mechanical current noise limited SNR. It is observed that the frequency response is dominated by two vibroacoustic limiting mechanisms: Bragg’s scattering, determined by array lateral dimensions, and crosstalk actuated fundamental and antisymmetric array modes, determined by individual membrane dynamics. Based on the limiting mechanism frequencies, a simplified design methodology is developed and used to design two CMUT array sets covering a broad frequency range of 1-80MHz. These CMUT arrays are fabricated and their limiting mechanisms are experimentally verified through pressure and admittance measurement and simulation comparison. CMUT arrays for guidewire IVUS application are implemented and successfully interfaced with ASICs to demonstrate imaging at 40MHz. Considering that CMUT array performance is also susceptible to the electrical termination conditions, the simulation model is utilized to investigate the effect of different impedance matching scenarios. Receiver performance of the integrated CMUT array and termination circuitry is analyzed through the system’s SNR and acoustic reflectivity.
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technology
dc.subjectCMUTs
dc.subjectCMUT design
dc.subjectImaging array design
dc.subjectHigh frequency ultrasound imaging
dc.subjectCrosstalk
dc.subjectBragg's resonance
dc.subject
dc.titleCMUT array design and fabrication for high frequency ultrasound imaging
dc.typeDissertation
dc.description.degreePh.D.
dc.contributor.departmentMechanical Engineering
thesis.degree.levelDoctoral
dc.contributor.committeeMemberSabra, Karim
dc.contributor.committeeMemberHesketh, Peter
dc.contributor.committeeMemberArvanitis, Costas D.
dc.contributor.committeeMemberLindsey, Brooks
dc.date.updated2021-06-10T13:54:04Z


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record