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Advances in Materials Science and Engineering
Volume 2015 (2015), Article ID 584324, 5 pages
Research Article

Water Vapor Sensors Based on the Swelling of Relief Gelatin Gratings

1Centro de Investigaciones en Optica, Loma del Bosque 115, 37000 León, GTO, Mexico
2Departamento de Fisica Aplicada y Electromagnetismo, Universidad de Valencia, Dr. Moliner 50, Burjassot, 46100 València, Spain

Received 4 December 2014; Revised 27 February 2015; Accepted 11 March 2015

Academic Editor: Luigi Nicolais

Copyright © 2015 Sergio Calixto and Miguel V. Andres. 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.


We report on a novel device to measure relative humidity. The sensor is based on surface diffraction gratings made of gelatin. This material swells and shrinks according to the content of water vapor in air. By sending a light beam to the grating, diffracted orders appear. Due to the gelatin swelling or shrinking, first order intensity changes according to the relative humidity. Calibration curves relating intensity versus relative humidity have been found. The fabrication process of diffraction gratings and the testing of the prototype sensing devices are described.