title: Colorimetric sensors using nano-patch surface plasmon resonators.
abstract: A two-dimensional array of gold nano-patches on a highly reflective mirror is proposed for refractive index sensing based on changes in the reflected colors. The grating on the mirror creates localized surface plasmon resonances resulting in a minimum in the visible reflectance spectra. The wavelength of the resonance can be tuned by changing the width of the nano-patches and is also dependent on the refractive index of the surrounding medium. The color variation due to change in the refractive index is measured and used to realize a simple low-cost sensor with a refractive index resolution better than 10⁻⁵ just using image processing. The efficacy of the proposed sensor is also demonstrated for surface sensing by depositing thin layers of silicon dioxide. The color difference due to the addition of a 3 nm thick layer of silicon dioxide is detectable by the naked eye and deposition thickness of 2 Å can be resolved using image processing.
authors.affiliation: Department of Electrical and Computer Engineering, and Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada. mkhorasa@uwaterloo.ca
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Khorasaninejad
authors.forename: S
authors.initials: S
authors.lastname: Mohsen Raeis-Zadeh
authors.forename: Hadi
authors.initials: H
authors.lastname: Amarloo
authors.forename: Navid
authors.initials: N
authors.lastname: Abedzadeh
authors.forename: Safieddin
authors.initials: S
authors.lastname: Safavi-Naeini
authors.forename: Simarjeet Singh
authors.initials: SS
authors.lastname: Saini
mesh_terms: D003124:Colorimetry / Q000295:instrumentation*; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D012031:Refractometry; D012822:Silicon Dioxide / Q000032:analysis; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D006046:Gold; D012822:Silicon Dioxide