PASSIVE COOLING
Researchers from the Dept. of Materials Science and Engineering at the Massachusetts Institute of Technology (MIT; Cambridge; www.mit.edu) have developed a new two-layered material that mimics the cooling behavior of camel fur, which could provide extended cooling to preserve perishable goods without using external refrigeration or power. The new material has a bottom hydrogel layer that mimics the camel’s sweat glands. This gelatin-like substance consists mostly of water contained in a sponge-like matrix. The water can evaporate from the hydrogel, thereby lowering the temperature. The hydrogel is covered with an upper layer of aerogel, which acts as the camel’s fur by insulating against external heat while allowing the vapor to pass through.
Field tests and detailed analysis have shown that this new two-layer material, less than a half-inch thick, can provide cooling of more than 7°C for five times longer than the hydrogel alone — more than eight days versus less than two, says MIT. The findings were described in the journal Joule last month.
The researchers say the system could be used for food packaging to preserve freshness, as well as for keeping medicines, such as vaccines, safe when delivered to remote locations.