Sensor Used in E-nose - The Electronic Nose Artificial Olfaction Technology - page 166

6.9.1 Optical Fiber

Optical fiber sensors utilize glass fibers coated with thin chemically active mate-
rials on their sides or ends that contain immobilized fluorescent dyes in an organic
polymer matrix as shown in Fig. 6.20 . The changes in dye polarity cause a shift in
the emission spectrum (color change) due to interaction of volatiles with a light
source. Wide sensitivities are obtainable owing to availability of different dyes;
however, they have a limited lifetime because of photobleaching.

6.9.2 Surface Plasmon Resonance

The SPR is an optical technique that uses the evanescent wave phenomenon to
measure changes in the refractive index near the sensor surface. SPR is an optical

Fig. 6.20 A gas optical fiber sensor [ 29 ]