Optical Fiber Relative Humidity Sensor Based on a FBG with a Di-Ureasil Coating


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.



subject category

Chemistry; Electrochemistry; Instruments & Instrumentation


Correia, SFH; Antunes, P; Pecoraro, E; Lima, PP; Varum, H; Carlos, LD; Ferreira, RAS; Andre, PS

our authors


The authors acknowledge the financial support from Fundacao para a Ciencia e Tecnologia (FCT), FEDER, COMPETE through PTDC/CTM/101324/2008 and PEst-C/CTM/LA0011/2011. The PhD (SFRH/BD/41077/2007) and Postdoctoral SFRH/BPD/34365/2006, SFRH/BPD/76735/2011) fellowships are also gratefully acknowledged.

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