Nafion film temperature/humidity sensing based on optical fiber Fabry-Perot interference

A simple method based on Capillary action is proposed to fabricate an optical fiber Fabry-Perot sensing probe for temperature and humidity measurement. Nafion film serves as the thermal and humidity sensing material in this optical fiber sensor. The sensor is constructed by manually depositing a drop of Nafion solution in the capillary and inserting a single mode optical fiber into the capillary. For humidity sensing, we use a fiber Bragg grating (FBG) as temperature compensator. The sensitivity, repeatability, and stability of the sensor were evaluated by analyzing the reflection spectra of the interference fringes. The results indicate that Nafion can be used as the sensing phase of an optical fiber temperature and humidity sensor based on the optical fiber Fabry-Perot interference, presenting a sensitivity of 2.71 nm/°C and 3.78 nm/%RH.