An optical gas sensor based on ellipsometric readout

A gas sensor based on off- ellipsometric readout is presented. It includes miniaturization of a ellipsometer facilitating multisensing. and small optical components are used. Some experimental results on low concentration alcoholic gases (methanol, ethanol and 2-propanol) with porous silicon and chemically modified porous silicon as sensing layers are shown. Currently, the lower detection limit for these gases is about 1 ppm. Optimization of the sensor system and improvement of sensitivity or alteration of selectivity by modification of the sensing layer is also discussed.