Selective Methanol Gas Detection using a U-bent Optical Fiber Modified with a Silica Nanoparticle Multilayer

Abstract

SUMMARY The development of an evanescent wave optical fiber sensor modified with an organic–inorganic hybrid nanoporous thin film for the detection of organic solvent vapors was demonstrated. The optical fiber with a core diameter of 200 μm was bent into U‐shape to enhance the penetration depth of light transferred into the evanescent field, and modified with a multilayered thin film of poly (allylamine hydrochloride) and silica nanoparticles (PAH/SiO2)n, via layer‐by‐layer (LbL) film deposition. The mesoporous film structure led to higher molecular diffusion and the highest selectivity to methanol among the six alcohols and water, which were used as target analytes, by the aid of tetrakis (4‐sulfophenyl) porphine (TSPP) infused inside the film.