Responsive hydrogels filling the interstitial spaces of photonic crystals can form mesoscopically structured materials, which exhibit reversible shifts in the Bragg diffracted light as a response of environmental changes. These materials can be used to generate chemical or biochemical sensors. The present work reports on the synthesis and characterization of ethanol responsive hydrogels that can be used in the design of novel breathalyzers. The dynamic mechanical behavior of the macroscopic hydrogels and their swelling features in the presence of different liquids or vapors have been investigated to orientate the choice of the best responsive material and curing process. The swelling behavior of a selected hydrogel embedding the photonic crystal made of polystyrene nanoparticles as function of the concentration of ethanol vapor was studied through UV-Vis optical transmission spectroscopy and compared to the behavior of the macrogel analogue. (C) 2014 Elsevier Ltd. All rights reserved.