Sensors 2012, 12(7), 8847-8860; https://doi.org/10.3390/s120708847
Optical Fiber Relative Humidity Sensor Based on a FBG with a Di-Ureasil Coating
Sandra F. H. Correia 1,2, Paulo Antunes 1,3
, Edison Pecoraro 3,4, Patrícia P. Lima 1,2, Humberto Varum 5, Luis D. Carlos 1,2, Rute A. S. Ferreira 1,2,*
and Paulo S. André 1,3,*
, Edison Pecoraro 3,4, Patrícia P. Lima 1,2, Humberto Varum 5, Luis D. Carlos 1,2, Rute A. S. Ferreira 1,2,*
and Paulo S. André 1,3,*
1
Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal
2
CICECO, University of Aveiro, 3810-193 Aveiro, Portugal
3
Instituto de Telecomunicações, 3810-193 Aveiro, Portugal
4
Instituto de Química, Universidade Estadual Paulista, Araraquara 14800-900, SP, Brazil
5
Department of Civil Engineering, University of Aveiro, 3810-193 Aveiro, Portugal
*
Authors to whom correspondence should be addressed.
Received: 28 May 2012 / Revised: 20 June 2012 / Accepted: 25 June 2012 / Published: 27 June 2012
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Portugal)
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. View Full-TextKeywords:
fiber Bragg gratings; optical fiber sensors; relative humidity; organo-silica hybrid; structure health monitoring
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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MDPI and ACS Style
Correia, S.F.H.; Antunes, P.; Pecoraro, E.; Lima, P.P.; Varum, H.; Carlos, L.D.; Ferreira, R.A.S.; André, P.S. Optical Fiber Relative Humidity Sensor Based on a FBG with a Di-Ureasil Coating. Sensors 2012, 12, 8847-8860.