Innovative Low-Cost Plastic Optical Fiber Sensors for Gas Monitoring

Abstract

In this study, a new simple and low-cost plastic optical fiber sensor for the measurements of low concentration HF vapors is described. The sensitivity to the HF vapors obtained by depositing a thin glass-like layer onto the PMMA core fiber after removing the fluorinated polymer cladding via dipping the fiber into ethyl acetate for a short period, not more than 40 second. Moreover, in order to enhance the fiber sensitivity, low pressure plasma treatments have been carried out in O 2 and Ar gas mixtures on polymeric optical core fibers in order to increase the core surface area without damaging the PMMA core fiber. The reaction of glass-like layer with the HF vapor alters the fiber light transmission and is detected by means of a wide-band photodiode. POF sensors can find relevant applications for monitoring people exposed to unhealthy atmospheres in civil and industrial fields, and for monitoring the pollutants in gaseous mixtures. Several prototypes of fiber sensors have been fabricated and characterized in the reaction chamber. The obtained results demonstrating the capability to detect low concentration of HF vapors with high sensitivity.