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pH Measurements Using Simple Fiber-Optic Instrumentation and Luminescence Detection

Fiber optic sensing for chemical analysis is a growing technology, since it offers several advantages, as analysis can be done "in situ" in real time, the sensing techniques do not disturb the process, so the sample size can be extremely small and the sensing locations can be in remote areas. Fluorescence measurements are particularly well-suited for optical sensing due to their sensitivity when compared to absorption measurements (Arregui, 2002). Here, we describe the electronic design and the performance of a fiber optic fluorescent-based pH sensor. The chemical sensing phase consists of an organic pH indicator (mercurochrome) immobilized in a sol-gel matrix and placed at the end of a fiber optic by means of a steel grid