title: Sub-micrometric reflectometry for localized label-free biosensing.
abstract: In this work we present an optical technique for characterizing sub-micrometric areas based on reflectivity of the light as a function of angle of incidence for the two pure polarizations s and p, covering a range of angles of incidence from -71.80° to 71.80° with a resolution of 0.1°. Circular areas with a diameter in the order of 600 nm can be characterized, and the spectra for the two polarizations can be obtained with a single measurement. For biosensing purposes, we have fabricated several Bio Photonic Sensing Cells (BICELLs) consisting of interferometers of 1240 nm of SU-8 polymer over silicon. An indirect immunoassay is performed over these BICELLs and compared experimentally with FT-VIS-NIR spectrometry and theoretical calculations. The Limit of Detection (LoD) achieved is comparable with standard high resolution spectrometry, but with the capability of analyzing sub-micrometric domains for immunoassays reactions onto a sensing surface.
authors.forename: R
authors.initials: R
authors.lastname: Casquel
authors.forename: J A
authors.initials: JA
authors.lastname: Soler
authors.forename: M
authors.initials: M
authors.lastname: Holgado
authors.forename: A
authors.initials: A
authors.lastname: López
authors.forename: A
authors.initials: A
authors.lastname: Lavín
authors.forename: J
authors.initials: J
authors.lastname: de Vicente
authors.forename: F J
authors.initials: FJ
authors.lastname: Sanza
authors.forename: M F
authors.initials: MF
authors.lastname: Laguna
authors.forename: M J
authors.initials: MJ
authors.lastname: Bañuls
authors.forename: R
authors.initials: R
authors.lastname: Puchades