Gl. Duveneck et al., NOVEL BIOAFFINITY SENSORS FOR TRACE ANALYSIS BASED ON LUMINESCENCE EXCITATION BY PLANAR WAVE-GUIDES, Sensors and actuators. B, Chemical, 38(1-3), 1997, pp. 88-95
We have developed a novel generation of optical bioaffinity sensors fo
r ultra trace analysis. These sensors are based on luminescence genera
tion in the evanescent field of high-refractive-index single-mode plan
ar waveguides. With the waveguiding layers and the grating parameters
chosen, very sharp discrimination of bulk against surface-confined exc
itation, in combination with high excitation intensities in the evanes
cent field, can be achieved, leading to unprecedented sensitivity. Exp
erimental data of the optimization of the transducer parameters will b
e presented. Incoupling of excitation light is performed using diffrac
tive gratings. Different methods for the detection of both transmitted
and luminescence light will be presented. The transmitted excitation
light can be detected either at the distal waveguide chip end or using
a second outcoupling grating. Both isotropically emitted luminescence
, collected by a lens located below the transducer substrate ('volume
detection'), and emission coupled back into the waveguiding layer can
be monitored, the latter via a second outcoupling grating, First exper
imental results obtained in model bioaffinity assays will be presented
, demonstrating the feasibility of the different detection methods men
tioned above, as well as the superior sensitivity of our novel sensor
configuration. In still preliminary experiments, 100 attomoles of fluo
rescently labelled DNA (16-mer oligonucleotide), applied at 100 femtom
olar concentration, can be detected.