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International Journal of Polymer Science
Volume 2016, Article ID 8471903, 7 pages
Research Article

Azobenzene-Based Gel Coated Fibre Bragg Grating Sensor for Moisture Measurement

Centre for Defence Chemistry, Cranfield University, Defence Academy of the UK, Shrivenham, Swindon, Wiltshire SN6 8LA, UK

Received 17 February 2016; Revised 10 May 2016; Accepted 11 July 2016

Academic Editor: Chalongrat Daengngam

Copyright © 2016 Mohammed Moniruzzaman and John Rock. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A fibre Bragg grating sensor is coated with a novel polymer gel in order to investigate its suitability for nondestructive measurement of moisture in materials that can potentially lose their integrity due to moisture ingress. Absorption and desorption of moisture lead to swelling/shrinkage of an azobenzene-based gel, which induces a strain in the Bragg grating resulting in wavelength shifts. The results demonstrated that the amount of wavelength shift is linearly dependent on the amount of water ingress by the gel. The performance of the proposed optical fibre moisture sensor was found to be repeatable with no detectable hysteresis and has the potential to offer a low-cost route for monitoring moisture content.