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Descripción
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| Technology for nano-scale integration is achieving promising results for the development of novel sensors systems to explore its application to important medical, biopharmaceutical and environmental applications such as drug development and immunoassays. They use well-known optical structures such as waveguide Surface Plasmon Resonance (SPR), Mach-Zehnder (M-Z) interferometers, two-mode waveguide interferometry, but need complex optical coupling such as inverted taper and grating couplers. The proposed system is based on the observation of external reflectivity profiles. A dielectric micro-nano structure consisting of a triangular lattice of sub-micro-holes fabricated on a SiO2/Si wafer produces spectra interference patterns as a function of the angle of incidence for both p and s polarization directions as well as a phase shift between s and p polarisation. The measurements have been performed simultaneously by using a linearly polarized laser operating at 675 nm with a tightly focussed beam, which provides a sub-micrometer spot and therefore allow these measurements to be accomplished in a single sub-micro-hole. Consecutively the reflectivity of the photonic structures is measured and analyzed over a wide range of wavelengths of light as well. The sub-micro-holes are filled with optical liquids with different refractive indices, involving a change in the effective refractive index which produces variations in the phase shift and the interference reflectivity patterns. The optical system is able to measure extremely small volumes of analyte (approximately 0.1 femtolitres per hole). The simultaneous use of three optical techniques, remove ambiguities and improve reliability. The detection limit achievable with this system is up to 10−6 R.I.U. which is competitive with the current state of the art, and could be improved with not complex changes for all the optical techniques. Furthermore, the complexity of coupling in the current photonic label-free biosensors is avoided, as the light is collected normally. | |
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Internacional
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Si |
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JCR del ISI
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Si |
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Título de la revista
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Sensor Letters |
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ISSN
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1546-198X |
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Factor de impacto JCR
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1,587 |
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Información de impacto
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Volumen
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6 |
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DOI
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doi:10.1166/sl.2008.430 |
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Número de revista
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4 |
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