Alteration in the response of fluorescein immobilized in sol-gel thin films as an optical fiber sensing mechanism for pH

摘要

Chemical dye immobilization is very commonly used for optical fiber chemical sensors development. The dye may behave differently in aqueous state and in immobilized state. This paper describes the experimental results on absorption, emission and pH response of chemical indicator sodium fluorescein, both as dissolved in water and immobilized in sol-gel thin film, for optical fiber pH sensors development. It was found that in the sol-gel immobilized state, by altering the dye concentration and excitation/emission wavelength, a wide range of measurements from pH 0.5 to pH 10 is possible.