Decoupling temperature and humidity with chitosan-coated tilted FBG sensor

This work proposes a chitosan-coated tilted fiber Bragg grating sensor for the first time to simultaneously monitor temperature and relative humidity (RH). The sensing principle used allows for the discrimination between temperature and RH as the Bragg peak was verified to be insensitive to RH while exhibiting a measured sensitivity to temperature of (8.7 ± 0.1) pm/°C. On the other hand, the sensitivities of the spectral minimum peak, corresponding to a cladding mode, were measured as (8.0 ± 0.1) pm/°C and (0.88 ± 0.06) pm/%RH for temperature and RH, respectively.