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Optical sensing elements for nitrogen dioxide (NO.sub.2) gas detection, a sol-gel method for making the sensing elements and fiber optic sensors incorporating nitrogen dioxide gas optical sensing elements

United States Patent

July 3, 2007
View the Complete Patent at the US Patent & Trademark Office
A sensing element, a method of making a sensing element, and a fiber optic sensor incorporating the sensing element are described. The sensor can be used for the quantitative detection of NO.sub.2 in a mixture of gases. The sensing element can be made by incorporating a diazotizing reagent which reacts with nitrous ions to produce a diazo compound and a coupling reagent which couples with the diazo compound to produce an azo dye into a sol and allowing the sol to form an optically transparent gel. The sensing element changes color in the presence of NO.sub.2 gas. The temporal response of the absorption spectrum at various NO.sub.2 concentrations has also been recorded and analyzed. Sensors having different design configurations are described. The sensing element can detect NO.sub.2 gas at levels of parts per billion.
Mechery; Shelly John (Mississippi State, MS), Singh; Jagdish P. (Starkville, MS)
Mississippi State University (Mississippi State, MS)
10/ 693,519
October 27, 2003
This U.S. Government has certain rights in this invention as provided for by the terms of Contract No. DE-FC26-98FT-40395, awarded by the United States Department of Energy.