A protein derived from squid skin could be adapted into a kind of IR camouflage for soldiers. Researchers from the University of California, Irvine, have developed an adhesive film that, when stretched, reflects near-infrared light. Future versions of the technology that reflect a broader part of the IR spectrum could be worn by soldiers hoping to avoid detection by enemy thermal cameras. “Soldiers wear uniforms with the familiar green and brown camouflage patterns to blend into foliage during the day, but under low light and at night, they’re still vulnerable to infrared detection,” said professor Dr. Alon Gorodetsky. “We’ve developed stickers for use as a thin, flexible layer of camo with the potential to take on a pattern that will better match the soldiers’ infrared reflectance to their background and hide them from active infrared visualization.” Squid skin features unusual cells known as iridocytes, which contain layers or platelets composed of a protein called reflectin. The animal uses a biochemical cascade to change the thickness of the layers and their spacing, which alters how the cells reflect light. Gorodetsky’s group used bacteria to produce reflectin. One way to make the film reflective in the IR spectrum is to expose it to acetic acid vapor, but this isn’t practical for soldiers in the field. Instead, Gorodetsky’s team applied the protein to flexible polymer substrates — essentially, household sticky tape. The tape adheres to a range of surfaces, including cloth uniforms, and its appearance under an IR camera can be changed by stretching, a mechanical trigger that might more realistically be used in military operations. “We’re going after something that's inexpensive and completely disposable,” Gorodetsky said. “You take out this protein-coated tape, you use it quickly to make an appropriate camouflage pattern on the fly, then you take it off and throw it away.” The film may also have uses outside the military, for example in clothing that selectively traps or releases body heat to keep people comfortable in different environments. The research was presented at the 249th National Meeting & Exposition of the American Chemical Society (ACS). For more information, visit www.uci.edu.