The research work developed in this thesis is focused on obtaining an optical biosensor, which does not need chemical amplification (label-free), which has high sensitivity and is cost efficiency. This biosensor is based on arrays of resonant nanopillars (R-NPs), composed of pairs of Bragg reflectors of silicon nitride and silicon oxide (Si3N4/SiO2) and a central cavity of silicon oxide (SiO2) arranged on a quartz substrate. A resonant nanopillar has an optical response consisting of a spectral band gap that prevents the light transmission (photonic gap) except in a specific range of the band, where the light is transmitted (resonance), due to the central cavity. The light is guided by each R-NP, and due to their nanometric character, part of the light travels outside of the nanopillar, observing thus, what is on the surface.
Although each R-NP acts as a single nanosensor, it would be very difficult to observe the response of a single R-NP because of its small size, so R-NPs are arranged into arrays. Their proximity produces an effect of light concentration outside of the surface of the R-NPs. This phenomenon is known as concentration of light by evanescent field. In addition, this arrays, allow biological sample to infiltrate the matrix formed by the R-NPs, and thus they can observe: on one hand the change in the optical properties of the liquid, and on the other hand, the immobilization of a bioreceptor, and the affinity reactions between such bioreceptor and the target molecule to be detected (analyte). Thus, the optical biosensor here developed can be applied for a wide range of purposes, as for example for small pollutant detection in the frame of the Enviguard European Project.