Abstract

Olfactory sensors are of interest for use in component analysis and environment monitoring. Various electronic and optical sensors are based on vapor-induced dimensional changes in a chemically selective polymer. In the electronic case, for example, the polymers are doped with carbon-black and the dimensional change is measured by a resistance change. We measure the dimensional change using a photorefractive two-beam coupling novelty filter. An array of polymer sensing elements are placed on a prism that forms one arm of a novelty-filter interferometer. A change in the vapor concentration produces an output that is detected with a CCD and a single- element detector. We implement a "sniff-lock-loop" to synchronize the detected signal with sensor vapor inhalation to improve detector signal-to-noise. We have achieved, for example, vapor sensitivity to hexane to better than 200 ppm vapor concentration. The optical holographic sensor can simultaneously accommodate a large number of different polymer sensors.

© 2001 Optical Society of America