title: An optical fiber sensor for remote pH sensing and imaging.
abstract: A fiber-optical probe for pH sensing and real-time imaging is successfully fabricated by connecting a polymer imaging fiber and a gradient index (GRIN) lens rod which was modified with a sensing film. By employing an improved metallographic microscope, an optical system is designed  to cooperate with the probe. This novel technique has high-quality imaging capabilities for observing remote samples while measuring pH. The linear range of the probe is pH 1.2-3.5. This technique overcomes the difficulty that high-quality images cannot be obtained when directly using  conventional imaging bundles for pH sensing and imaging. As preliminary applications, the corrosion behavior of an iron screw and the reaction process of rust were investigated in buffer solutions of pH 2.0 and 2.9, respectively. The experiment demonstrated that the pH values of the analytes'  surface were higher than that of buffer solutions due to the chemical reaction. It provides great potential for applications in optical multifunctional detection, especially in chemical sensing and biosensing.
authors.affiliation: Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, 454003 China. jianwang@opt.ac.cn
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
mesh_terms: D002138:Calibration; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D003343:Corrosion; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D055100:Optical Fibers
chemical_list: D007501:Iron