By Bridgette Meinhold, Source: Ecouterre

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The concept is simple – when you’re hot a cold cloth applied to your skin helps you feel cooler and the same is true when you’re cold. A change in temperature on your skin makes you perceive an a different overall thermal comfort. So using that concept, st
udents at MIT developed Wristify, a thermoelectric bracelet that changes temperature to help you be more comfortable. The concept goes further than just helping you feel cooler on a hot day, imagine that if everyone wore this little device how much we could reduce air conditioning or heating inside a building and save a load of energy and money.
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Wristify was developed by MIT students Sam Shames, Mike Gibson, David Cohen-Tanugi, and Matt Smith, who competed and won first prize in the annual MADMEC competition. This year’s competition asked students to create products that provides Materials Science Solutions for Sustainability. As Sam Shames explains about their winning prototype, “What we developed is a wearable, wrist-based technology that leverages human sensitivity, can detect and perfect rates of change, and can maintain overall thermal comfort while reducing the need to heat and cool buildings.”

Human skin is very sensitive to rapid changes in temperature and a small change in a localized portion can affect the overall feeling throughout the body. The Wristify’s team learned that by applying a change of 0.1 C per second to a part of the skin can make the person feel warmer or cooler by a few degrees. Their prototype is a watch-like device that can be powered, for up to eight hours, by a lithium polymer battery. On top is a custom copper-alloy-based heat sink that works to dissipate heat or cold, while a control system manages the intensity and duration of the thermal pulses delivered to the heat sink. Temperature sensors monitor skin and ambient air temperature to help the device adjust accordingly.

Such a device used by many people can help reduce the need for indoor climate control and thus save energy and money and improve sustainability. The team’s first prize at the MADMEC VII competition awarded them $10,000, which was sponsored by MIT’s Department of Materials Science and Engineering, Saint Gobain, BP, and the Dow Chemical Company. Now the team plans to use the winnings to further develop the prototype and create more advanced algorithms to better control the thermal pulses.