Tuesday, 22 August 2017 00:00

PhD Thesis: Label-free Optical Biosensors based on Resonant Nanopillars

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Ana López Hernández from Universidad Politécnica de Madrid(UPM) has presented her doctoral thesis in Environmental Engineering, Chemistry and Materials at the Higher Technical School of Industrial Engineers of the Polytechnic University of Madrid entitled "Label-free Optical Biosensors based on Resonant Nanopillars" that develops a research work applicable to the work framework of the project.

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.

Read 96 times Last modified on Friday, 17 November 2017 11:37

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logo1This project has received funding from the European Union’s Seventh Framework Programme
for research, technological development and demonstration under grant agreement no 614057
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