We are currently developing pH sensitive dye doped clad modified evanescent optical fiber (CMEOF) sensor array for the detection of aqueous-ammonia. The quasi-distribution of CMEOF ammonia sensors allows efficient measurement of aqueous-ammonia at several locations using a single fiber optic line. CMEOF sensors are fabricated by immobilized pH sensitive dyes in sol-gel and applying the dye doped sol-gel as a thin film around a bare core optical fiber. The CMEOF sensors are then sealed from water using a gas permeable membrane, PDMS-vinyl. The dyes in each CMEOF sensor are tailored to operate at slightly different wavelengths by appropriate choice of dyes. Wavelength-division-multiplexing (WDM) and linear system of equations (LSE) arc used to interrogate each CMEOF sensor and determine the concentration of aqueous-ammonia at each sensor location.
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