(390b) Ammonia Gas Sensing by Zeolite-Fiber Optic Device: Effects of Surface Modification and Operation Temperature

A ZSM-5 zeolite thin film is synthesized on a long period fiber grating (LPFG) optical device. This zeolite-fiber device is used for ammonia sensing by monitoring its resonance wavelength which shifts due to the change of the zeolite refractive index caused by adsorption of molecules in the zeolite. The selectivity, sensitivity and speed of response of the zeolite coated-LPFG to an analyte gas are determined by the equilibrium and transport properties of gas adsorption in the zeolite film. In this study, the ZSM-5 zeolite film is modified to increase its surface acidity that dramatically improves the sensitivity and selectivity for ammonia gas detection. The effect of operation temperature on the sensitivity, selectivity/specificity, and response time is experimentally investigated.