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This paper summarizes the development of a self-referenced, multi-channel, integrated optic chemical sensor technology for in-line monitoring of water quality in NASA's water revitalization subsystem, in the controlled ecological life support system for prolonged space missions. The technique uses commonly available materials and straightforward processing to produce channel waveguides in a porous glass, each channel treated with a fluorescence or absorbance based indicator that responds optically to metal ions in water. The porosity of the glass allows metal ions present in water to diffuse into the glass and interact with immobilized indicators, producing a measurable optical change.

Two critical sets of variables that must be monitored in life support systems for extended manned space exploration missions are: oxygen and trace gas concentrations in crew air supply and “respiratory” gasses (e.g. O2 and H2O vapor) in hydroponic or other regenerative food and oxygen producing units. This paper describes new results in the development of fiber optic sensors targeted at precisely these applications. In particular, we present new data on the performance (sensitivity, accuracy, and precision) of a moisture-insensitive oxygen optrode based on a fluorescent indicator immobilized in a permeable polymer, on a novel fiber optic humidity sensor, and on a miniature nitrogen dioxide optrode.