Physicists at the University of North Texas in Denton have conducted trials using a type of polymer gel called a hydrogel that may play a role in new display or sensor technologies. The hydrogels swell or shrink when environmental stimuli such as a change in temperature or exposure to an IR light source cause them to absorb or discharge water between cross-linked polymer chains.The polymer hydrogel is shown at room temperature (right). A dinosaur figure appears as heating begins (far right). The researchers placed a layer of the hydrogel on a transparent substrate. Using a photomask, they deposited gold specks on the hydrogel, which allowed them to vary the periodicity of the array and make it suitable for sensors or displays.