Conception d'un laboratoire sur fibre pour l'analyse in vivo

This work presents the proof of concept of the detection of optical index changes by surface plasmon resonance (SPR) thanks to optical fiber bundles. This proof of concept is the first essential step for the future design of a lab on fiber tool dedicated to molecular analysis for endoscopic diagnosis. Our approach is based on nanotextured optical fiber bundles comprising several thousands of individual optical fibers. These nanostructures were coated by a thin gold layer in order to exhibit interesting optical properties like SPR. The sensitivity of the bundle to optical index changes and the detection limit were measured in retro-reflection. We performed numerical simulations in order to enhance these performances based on an optimization of the fiber end geometry and the gold coating thickness. We finally obtained a detection limit of 10-4 refractive index unit, which is fully compatible with the detection of biological interactions involving large proteins or bacteria.