When Arthur Dent left Earth in The Hitchhiker’s Guide to the Galaxy, Ford Prefect advised him to carry a towel everywhere he went. After all, it has just so many uses, including the ability to "wrap it around you for warmth as you bound across the cold moons of Jaglan Beta." Makes sense, since a warm towel (or a cool one) can change your whole body temperature.
Clearly, researchers at MIT haven’t read Hitchhiker’s Guide, because a group of them decided to create something overly complicated called Wristify. It’s a thermoelectric bracelet that continuously monitors air and skin temperatures and using that information, sends waveform pulses of heat or coolness to the wrist, maintaining a nice temperature. It's like the body’s heating, ventilation, and air conditioning (HVAC) system.
Human skin is incredibly sensitive to temperature. All that’s needed is to spot-heat or spot-cool a small part of the body. Using certain pressure points, like the back of the neck or the wrist, yields great results. By changing the temperature of that spot at a rate of .1 degree C per second, the entire body feels several degrees hotter or colder, respectively. It’s important to note that the body isn’t actually that much warmer or cooler, but that it’s being (somewhat) tricked into feeling that much warmer and cooler.
A device like Wristify could save a huge chunk of change (not to mention energy) by making actual HVAC systems less necessary. "Buildings right now use an incredible amount of energy just in space heating and cooling. In fact, all together this makes up 16.5 percent of all U.S. primary energy consumption. We wanted to reduce that number, while maintaining individual thermal comfort," said Wristfy co-inventor Sam Shames. "We found the best way to do it was local heating and cooling of parts of the body."
At present, Wristify is merely a prototype, but it won its inventers $10,000 and first price at MIT’s Making and Designing Materials Engineering Competition, which bodes well for its future.