Fans of Arnold Schwarzenegger movies will remember Predator, in which an alien hides from a group of soldiers using a cloaking device that renders it invisible. Now scientists have developed a way to do a similar trick in the infrared spectrum of light.
At the University of California, Irvine, a team led by Alon Gorodetsky, an assistant professor of chemical engineering and materials science, made a thin film that can change color and reflectivity in response to an outside signal. The films appear and disappear, becoming invisible in infrared. The study appeared in the journal Advanced Materials.
The key is a protein called reflectin. It’s a protein that lets squids and their relatives, the octopus and the cuttlefish, rapidly change color. The protein changes in response to chemical stimuli.
Being invisible in the infrared would be very useful to the military. Some night vision equipment, targeting systems and motion detectors use that part of the spectrum — anyone wearing a coat of this new film would be hidden. The coating is invisible in the range of 700 to 1,200 nanometer wavelengths, just where many infrared detection equipment operates.
To make this coating practical, the researchers will need a way to mass-produce reflectin, as well as finding a way to transmit the “change” signal without using chemicals — perhaps an electrical signal of some sort.