Chloride sensing using optical probe

Abstract

A new approach to anion sensing is presented using Cl⁻ as a model species. The sensing electrode is an optical fiber with Bragg Grating (FBG) whose surface is coated with gold ultra-thin film. The sensing mechanism combines strain dependence of the Bragg wavelength with the change in capillary pressure on the fiber induced by Cl⁻ adsorption. Performance of the new sensor is illustrated at different potentials for a wide range of Cl⁻ concentrations. Phenomenological model of the transducing mechanism is presented to analyze and discuss sensing data. Our work illustrates a fast, real-time approach to chemical sensing which is generally applicable to any situation where chemical and/or electrochemical adsorption of targeted species occurs on the FBG sensor surface. This sensing approach should be of interest for areas of corrosion, biomedical and chemical engineering, health and medicine, and oil and gas extraction.