Intrinsic Fiber Optic pH Sensor for Measurement of pH Values in the Range of 0.5-6

The development, design, and evaluation of an intrinsic optical fiber pH sensor for low pH values (in the range of 0.5-6) based on fluorescence from a novel coumarin dye, which is covalently immobilized onto the end surface of an optical fiber is described. The sensor provides a rapid response (of approximately 25 s) over this pH range of 0.5-6.0, showing with very good stability over a period of several months. The sensor has also demonstrated insensitivity to ionic strength and excellent photostability through a series of laboratory tests