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Characterization of Bending Magnetostriction in Iron-Gallium Alloys for Nanowire Sensor Applications

dc.contributor.advisorFlatau, Alisonen_US
dc.contributor.authorDowney, Patricken_US
dc.date.accessioned2009-01-24T07:24:23Z
dc.date.available2009-01-24T07:24:23Z
dc.date.issued2008-11-21en_US
dc.identifier.urihttp://hdl.handle.net/1903/8874
dc.description.abstractThis research explores the possibility of using electrochemically deposited nanowires of magnetostrictive iron-gallium (Galfenol) to mimic the sensing capabilities of biological cilia. Sensor design calls for incorporating Galfenol nanowires cantilevered from a membrane and attached to a conventional magnetic field sensor. As the wires deflect in response to acoustic, airflow, or tactile excitation, the resultant bending stresses induce changes in magnetization that due to the scale of the nanowires offer the potential for excellent spatial resolution and frequency bandwidth. In order to determine the suitability for using Galfenol nanowires in this role, the first task was experimentally characterizing magnetostrictive transduction in bending beam structures, as this means of operation has been unattainable in previous materials research due to low tensile strengths in conventional alloys such as Terfenol-D. Results show that there is an appreciable sensing response from cantilevered Galfenol beams and that this phenomenon can be accurately modeled with an energy based formulation. For progressing experiments to the nanowire scale, a nanomanipulation instrument was designed and constructed that interfaces within a scanning electron microscope and allows for real time characterization of individual wires with diameters near 100 nm. The results of mechanical tensile testing and dynamic resonance identification reveal that the Galfenol nanowires behave similarly to the bulk material with the exception of a large increase in ultimate tensile strength. The magnetic domain structure of the nanowires was theoretically predicted and verified with magnetic force microscopy. An experimental methodology was developed to observe the coupling between bending stress and magnetization that is critical for accurate sensing, and the key results indicate that specific structural modifications need to be made to reduce the anisotropy in the nanowires in order to improve the transduction capabilities. A solution to this problem is presented and final experiments are performed.en_US
dc.format.extent38629052 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.titleCharacterization of Bending Magnetostriction in Iron-Gallium Alloys for Nanowire Sensor Applicationsen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentAerospace Engineeringen_US
dc.subject.pqcontrolledEngineering, Aerospaceen_US
dc.subject.pquncontrollednanowireen_US
dc.subject.pquncontrolledmagnetostrictionen_US
dc.subject.pquncontrolledGalfenolen_US
dc.subject.pquncontrolledMFMen_US
dc.subject.pquncontrolledshape anisotropyen_US
dc.subject.pquncontrollednanomanipulationen_US


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