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Recent efforts to develop integrated, multi-sensor chemical detection systems for life support and life science applications are presented. Sensors have been developed using a variety of transduction mechanisms, but the focus of the work described here is on optical chemical sensor development. Particular success has been realized in the area of fiber optic (optrode) sensors for monitoring pH in hydroponic growth media; in low (parts per billion) level detection of both atmospheric and dissolved NH3; and for monitoring CO2. In addition multichannel optoelectronic interfaces, employing all solid state optical sources and detectors have been designed and tested for use with these sensors. Recent work to assess the feasibility of using self-assembled monolayers and molecular assemblies, combined with microlithographic patterning techniques, for the detection of specific metals and anions in solution will also be presented.

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 insitu monitoring of atmospheric trace contaminants and nutrient solution parameters as required in life support systems or flight experiments. Sensors have been demonstrated for detection of ammonia, ethylene, carbon monoxide, pH and humidity.