Chemical sensors for environmental monitoring

Fiber optic chemical sensors are being developed for on-line monitoring of gases and liquids. The sensors utilize novel porous polymer or glass optical fibers in which selective chemical reagents have been immobilized. These reagents react with the analyte of interest resulting in a change in the optical properties of the sensor. These sensors (or optrodes) are particularly suited to in-situ detection of atmospheric trace contaminants and dissolved gases and chemicals, as may be required for environmental monitoring. Sensors have been demonstrated for low part-per-billion level detection of aromatic hydrocarbons, hydrazines and ethylene. Sensors have also been demonstrated for carbon monoxide ammonia, and humidity. Also, relevant to groundwater monitoring is the development of an integrated pH optrode system for the pH range 4 - 8, with additional optrodes for lower pH ranges.