Air-gap fiber-optic ammonia gas sensor.
A novel fiber-optic gas sensing arrangement based on an air-gap design is evaluated. In this arrangement, a small gap of air separates the internal solution from the sample. In addition, a second air-gap separates the internal solution from a fiber-optic probe which measures the fluorescence of the internal solution. A series of gas sensors for ammonia is used to investigate several critical design parameters. The length of the air-gap between the internal solution and the fiber-optic probe affects the magnitude of response. The length of the air-gap separating the internal and sample solutions has minimal effect on either magnitude or rate of response. As with membrane-type gas sensors, thickness of the internal solution and concentration of the indicator dye are the most important sensor parameters to consider when designing a fiber-optic gas sensor.
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Department of Chemistry, University of Iowa, Iowa city, IA 52242, U.S.A.
Arnold
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