Quantitative analysis of enhanced light irradiance in waveguide-based fluorescent microarrays.
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 optical waveguides to produce such fields are shown here 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 10(4) for adequately tailored waveguides. We deposited high-index TiO(2) 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.
Sagarzazu
Gabriel
G
Genewave, XTEC, Ecole Polytechnique Campus, 91120 Palaiseau, France.
Bedu
Mélanie
M
Martinelli
Lucio
L
Pelletier
Nicolas
N
Safarov
Viatcheslav I
VI
Weisbuch
Claude
C
Gacoin
Thierry
T
Benisty
Henri
H
D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017404:In Situ Hybridization, Fluorescence / Q000295:instrumentation*; D008029:Lighting / Q000295:instrumentation*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000295:instrumentation*