LAUSR

Abstract Relative Humidity (RH) sensors based on Fiber Bragg Grating (FBG) technology have been fabricated by polymer functionalization, using hygroscopic material, namely agar. The sensor is specifically intended to monitor moisture in stones of cultural heritage buildings and monuments, in particular to be positioned under hydrophobic coatings used for protecting stones from absorption of water and dissolved chemicals, thus providing early warning of coating deterioration by RH monitoring. The performance of the prototype was first tested exposing the sensors in controlled environment and then assessed for the application simulating “in field” operating conditions, with sensors installed on marble and travertine tiles. Results show that the proposed sensor is able to monitor the presence of moisture inside the stones.