Squid-inspired material keeps the heat – or loses it
Squids, octopi and cuttlefish are able to change the color of their skin thanks to specialized cells known as chromatophores. Scientists have now replicated the manner in which those cells work, resulting in a flexible material that can either trap or release heat as needed.
Each chromatophore contains a sac of pigment, which ordinarily appears as a small point. When the muscles surrounding one of the cells contract, however, that colored sac flattens into a disc shape, causing it to appear larger to an observer. Therefore, when a number of adjacent chromatophore sacs all flatten into one another, the animal's skin switches from being the underlying color to that of the pigment.
Inspired by this system, researchers at the University of California-Irvine have developed a material that incorporates a layer of tiny metal "islands" which border each other.
"In the relaxed state, the islands are bunched together and the material reflects and traps heat, like a traditional Mylar space blanket," says grad student Erica Leung, lead author of a paper on the research. "When the material is stretched, the islands spread apart, allowing infrared radiation to go through and heat to escape."
Leung adds that the material is lightweight, inexpensive, easy to manufacture, and stands up to thousands of stretching and releasing cycles. Once it's developed further, the scientists hope that the technology could be used in products such as space blankets, or perhaps in adaptive building insulation, tents that keep their occupants at a decent temperature in both cool and warm weather, and even clothing that lets multiple people stay comfortable in the same space.
"The temperature at which people are comfortable in an office is slightly different for everyone," says Assoc. Prof. Alon Gorodetsky, co-author of the paper. "Our invention could lead to clothing that adjusts to suit the comfort of each person indoors. This could result in potential savings of 30 to 40 percent on heating and air conditioning energy use."
In a demonstration of how such clothing might work, the scientists fashioned a sleeve from the material, which could be manually stretched or loosened via Velcro-like attachments. That sleeve was successfully used to modulate the skin temperature of a wearer's forearm.
The paper was recently published in the journal Nature Communications.
Source: University of California-Irvine