title: Optical fiber relative humidity sensor based on a FBG with a di-ureasil coating.
abstract: In this work we proposed a relative humidity (RH) sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values (15.0-95.0%) of the surrounding environment, allowing an increased sensitivity (22.2 pm/%RH) and durability due to the presence of a siliceous-based inorganic component. The developed sensor was tested in a real structure health monitoring essay, in which the RH inside two concrete blocks with different porosity values was measured over 1 year. The results demonstrated the potential of the proposed optical sensor in the monitoring of civil engineering structures.
authors.affiliation: Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal. sandracorreia@ua.pt
authors.forename: Sandra F H
authors.initials: SF
authors.lastname: Correia
authors.forename: Paulo
authors.initials: P
authors.lastname: Antunes
authors.forename: Edison
authors.initials: E
authors.lastname: Pecoraro
authors.forename: Patrícia P
authors.initials: PP
authors.lastname: Lima
authors.forename: Humberto
authors.initials: H
authors.lastname: Varum
authors.forename: Luis D
authors.initials: LD
authors.lastname: Carlos
authors.forename: Rute A S
authors.initials: RA
authors.lastname: Ferreira
authors.forename: Paulo S
authors.initials: PS
authors.lastname: André