An experimental study about hydrogels for the fabrication of optical fiber humidity sensors

A study about the optical sensitivity of four different hydrogels to the humidity is presented. The investigated hydrogels were poly-hydroxyethyl methacrylate, poly-acrylamide, poly-N-vinyl pyrrolidinone and agarose. These hydrogels were deposited on optical fiber by means of direct polymerization on the optical fiber surface. In addition, these materials were examined with different light sources, temperature and relative humidity conditions. The conclusion deducted from the experiments is that increasing the pore size of the hydrogels, the sensitivity and response time of these materials with the humidity is remarkably improved. (C) 2003 Elsevier B.V. All rights reserved.