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Scattering-Type Surface-Plasmon-Resonance BiosensorsBiosensors of a proposed type would exploit scattering of light by surface plasmon resonance (SPR). Related prior biosensors exploit absorption of light by SPR. Relative to the prior SPR biosensors, the proposed SPR biosensors would offer greater sensitivity in some cases, enough sensitivity to detect bioparticles having dimensions as small as nanometers. A surface plasmon wave can be described as a light-induced collective oscillation in electron density at the interface between a metal and a dielectric. At SPR, most incident photons are either absorbed or scattered at the metal/dielectric interface and, consequently, reflected light is greatly attenuated. The resonance wavelength and angle of incidence depend upon the permittivities of the metal and dielectric. An SPR sensor of the type most widely used heretofore includes a gold film coated with a ligand a substance that binds analyte molecules. The gold film is thin enough to support evanescent-wave coupling through its thickness. The change in the effective index of refraction at the surface, and thus the change in the SPR response, increases with the number of bound analyte molecules. The device is illuminated at a fixed wavelength, and the intensity of light reflected from the gold surface opposite the ligand-coated surface is measured as a function of the angle of incidence. From these measurements, the angle of minimum reflection intensity is determined
Document ID
20110014693
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
External Source(s)
http://www.techbriefs.com/component/content/article/165
Authors
Wang, Yu (California Inst. of Tech. Pasadena, CA, United States)
Pain, Bedabrata (California Inst. of Tech. Pasadena, CA, United States)
Cunningham, Thomas (California Inst. of Tech. Pasadena, CA, United States)
Seshadri, Suresh (California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2005
Publication Information
Publication: NASA Tech Briefs, January 2005
Subject Category
Man/System Technology And Life Support
Report/Patent Number
NPO-40683
Distribution Limits
Public
Copyright
Public Use Permitted.

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IDRelationTitle20110014676Collected WorksNASA Tech Briefs, January 2005
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