Bushra R. Mahdi, Hadi Dawyich AL-Attabi, Sadeq Dawood Salman
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pH sensor, fiber optic sensor, intensity modulated.
A fiber-optic pH sensor based on evanescent wave penetration is presented. Evanescent wave penetration is generated by removing the clad and contact the core with the solution. Testing samples were perpetrated by add a strong acid (HCL) or a strong base (NaOH) at distilled water to produce different value of pH (from 4 to 13). To determine the absorption or transmission of the evanescent waves, that generate after where obtained on appropriate calibration curve to determine a wide range of pH, by using pH indicators. Where using methyl red, by add fixed amounts of this dyes to the water samples were obtained on samples with colors vary with pH values. Calculate the transmission and absorption with draw a relationship between the transmissions or absorption with the pH values, to obtain on suitable curves, considered as calibration curves. Calibration curve for methyl red is best, where extends (from 4 to 12) for pH value. Can calculate the pH value for any water sample to tested, by the add the same ratios of the organic dyes it used.
