Quantitative analysis of enhanced light irradiance in waveguide-based fluorescent microarrays

Gabriel Sagarzazu (1) , Mélanie Bedu (1) , L. Martinelli (1) , Nicolas Pelletier (1) , Viatcheslav I. Safarov (1) , C. Weisbuch (2) , Thierry Gacoin (2) , Henri Benisty (3)

1 Genewave
2 LPMC - Laboratoire de physique de la matière condensée
3 LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique

Probing microarray assays in the presence of a hybridization mix retrieves precious information on hybridization kinetics. However, in common detection schemes, useful surface signals compete with the high supernatant background from labelled targets in the mix. A known solution consists in exciting specifically the microarray surface with evanescent fields. Configurations using planar opticalwaveguides to produce such fields are shownhere to present also a dramatic excitation irradiance enhancement at the guide/surrounding matter interface. We compare theoretically and experimentally a guided excitation with a classical external excitation. A full electromagnetic analysis predicts an irradiance increase higher than 104 for adequately tailored waveguides.We deposited high-index TiO2 sol–gel waveguides on glass substrates according to best simulations. Quantitative enhancement analysis exploiting actual biological fluorescent spots perfectly confirms the irradiance amplification effect of a thin waveguide. The impact of amplification on the design of biochip readers is discussed since it leaves ample margin for simple and low-cost light couplers, advantageous in affordable readers and sensor systems.

Mots clés: Fluorescence; Microarray; Waveguide; Evanescent field

Domaines: Optique [physics.optics]

Gabriel Sagarzazu, Mélanie Bedu, L. Martinelli, Nicolas Pelletier, Viatcheslav I. Safarov, et al.. Quantitative analysis of enhanced light irradiance in waveguide-based fluorescent microarrays. Biosensors and Bioelectronics, 2009, 24 (7), pp.2281. ⟨10.1016/j.bios.2008.11.001⟩. ⟨hal-00567021⟩