Deposited Nanorod Films for Biosensor Applications
Zhang, Wei
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https://hdl.handle.net/2142/72168
Description
Title
Deposited Nanorod Films for Biosensor Applications
Author(s)
Zhang, Wei
Issue Date
2009
Doctoral Committee Chair(s)
Cunningham, Brian T.
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Abstract
Planar photonic crystals have been used as the basis of many biological sensing devices. Here, we successfully demonstrate that the combination of the photonic crystal structures and a dielectric nanorod coating prepared by glancing-angle deposition method can lead to significant increases in the device sensitivity.
By incorporating a nanorod coating onto a label-free biosensor structure, the surface area of the device is increased. The sensitivity of high-surface-area sensors is compared with that of sensors without the high-surface-area coating. Results for detection of polymer films, proteins, and small molecules indicate up to a seven fold enhancement of detected adsorbed mass density.
When a nanorod coating is applied on top of the high-index layer of an enhanced-fluorescence biosensor, the emission intensity of a fluorescent dye on the device is increased by over 100 times compared to a reference glass slide. The increased sensitivity is due to the combined effects of enhanced near fields and enhanced surface area. The sensitivity is further increased by close to 200 times when a nanorod film is used as the high-index layer of the photonic crystal structure.
The planar photonic crystal is also combined with a SiO2-Ag "post-cap" nanostructure for applications in surface-enhanced Raman spectroscopy. It is demonstrated that the resonant near-fields of the photonic crystal could be used to couple light efficiently from a laser to the Ag nanoparticles to achieve a high surface-enhanced Raman spectroscopy enhancement factor.
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