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Thesis
A characterization of nanohole grating refractive index sensors for biosensing applications
Master of Science (M.S.), Drexel University
2012
DOI:
https://doi.org/10.17918/00008299
Abstract
Sub-wavelength periodic structures imprinted in metallic films give rise to enhanced transmission features which are sensitive to changes in refractive index at the surface. Variations in the transmission spectral output can be quantified to detect the concentration of analyte in a solution and the surface of the film can be readily modified with a variety of synthetic recognition elements, biomolecules, and well-established silane chemistry to allow for molecule recognition at the surface of the grating. These nanohole gratings can also be used to couple light into planar optical waveguides, which make ideal signal transducers because of their sturdiness, easy patterning of reagents, and easy incorporation of polymer materials. This thesis seeks to characterize nanohole structures imprinted on aluminum thin films as refractive index sensors that can be incorporated as transduction elements into biosensing technologies as well as to provide a path to optimization of an integrated biosensing device. Aluminum, a previously unexamined material for these nanohole array imprinted devices, was used as the metallic thin film in this thesis. The material demonstrated similar enhanced transmission effects to well known plasmonic materials like silver and gold, which cost significantly more than aluminum. The aluminum film was imprinted with a periodic nanoscale array of holes using an etching procedure, and then evaluated as a refractive index sensor. The bulk sensitivity of the nanohole array samples was determined through solvent characterization as well as exposure to varying thicknesses of a deposited layer of polymer. The ability of the potential transduction element to detect affinity reactions occurring at the surface was evaluated using well known biomolecular recognition experiments as well as synthetic recognition experiments using molecularly imprinted polymer films (MIPs). MIPs are biomimetic recognition elements that can be created for a variety of molecular structures, enable large-scale chip fabrication, are reusable, and offer superior stability when exposed to solvents and temperature extremes. The potential to combine the nanohole array transducer element with this synthetic recognition element is examined in this thesis. A theoretical optimization of the grating pitch for optimal detection capability was performed and the future path of optimizing an integrated biosensing device is discussed.
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Details
- Title
- A characterization of nanohole grating refractive index sensors for biosensing applications
- Creators
- Alyssa Bellingham
- Contributors
- Adam Fontecchio (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xvii, 63 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Electrical (and Computer) Engineering [Historical]; Drexel University
- Other Identifier
- 991021888730204721