MIT scientists have developed a thermoelectric bracelet that monitors the wearer's air and skin temperature, then sends pulses of cold or warm waveforms to their wrist to maintain the wearer's sense of temperature at comfortable levels.
Heating or cooling specific points of the human body in order to achieve a sense of comfort (in terms of temperature) is a very old technique (e.g. wet cloths on the foreheads of people with a high fever, etc.).
Wristify is based on this principle. It was developed by four mechanical engineering students (Sam Sams, Mike Gibson, David Cohen-Tanuggi, and Matt Smith), who won the $10,000 first prize in the MADMEC (Making and Designing Materials Engineering Competition).
The device is now in the working prototype stage. Although at first glance its use is considered to be aimed at the personal comfort (more precisely, the feeling of thermal comfort) of the user, its creators state that the ultimate goal is to reduce the energy consumption of buildings, by warming or cooling the person, not the building in which they are located.
“Currently, buildings use an incredible amount of energy just to heat and cool their spaces—in fact, that’s 16.5% of the total energy consumption in the U.S. We wanted to reduce that while still maintaining thermal comfort,” says S. Sams, one of the creators of Wristify. “We found that the best way to do that was to locally heat and cool parts of the body.”.
The team estimates that if the use of the device results in a building stopping its temperature from changing by even one degree Celsius, this will result in savings of 100 kilowatt hours per month.
While developing the technology, the Wristify team discovered that human skin is extremely sensitive to small, sudden changes in temperature, which affect the entire body. What they found was that they needed to heat or cool any part of the body (in this case, the wrist) at a rate of 0.1 degrees Celsius per second to make the entire body feel noticeably warmer or cooler.
After 15 prototypes, the team arrived at the final device, which resembles a wristwatch and can operate for eight hours on a full charge. The prototype demonstrated had a temperature change rate of 0.4 degrees per second.
The “watch” consists of a heat sink made of a special copper alloy and an automatic control system that manages the intensity and duration of the thermal pulses sent to the heat sink. “We have developed a technology that can be worn on the wrist, which calculates human sensitivity, can detect and refine rates of change and can maintain overall thermal comfort, while reducing the need to heat and cool buildings,” says Shames. With the prize money, the team plans to further develop the prototype, developing and using sophisticated algorithms.
Source: naftemporiki.gr
