Small Wearable Cooling Device

Cranking the AC or putting on and taking off additional layers of clothing isn’t always the most practical or convenient way of regulating your body temperature. Wouldn’t things be easier if you could just use smart wearable technology to solve the problem for you? A new research project developed by engineers at the University of California, San Diego, aims to help.

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Sony isn’t the only company trying to capitalize on the rising heat. Embr Labs is a startup founded by three MIT PhD students who were frustrated by the fact that their lab was always freezing cold during the summer, even when there were only a few people in the building.
Wouldn’t it make sense, they thought, to provide cooling devices to each individual inside the lab instead of using insane amounts of energy to chill vast spaces? Their solution is a small, $299 device called the Embr Wave that you wear on the inside of your wrist. At the press of a button, a ceramic plate that sits next to your skin gets really cold, providing you a bit of relief by targeting the sensitive thermoreceptor nerves that sit on the inside of your wrist. The company claims that, because Embr would allow people to cool themselves rather than their entire office or home, it could translate to energy savings of between 15% and 35% of a building’s overall cooling costs.

Creating a wearable that can cool you down is incredibly difficult, mostly because of the laws of physics: If you’re going to make something cold, you have to make something else warm. That’s why window A/C units stick out the window: They can blow hot air away from a building’s interiors, while they blow cold air inside. “When as you get smaller, especially if you want to get portable, it becomes more and more difficult to dissipate that heat,” says Sam Shames, a co-founder and chief operating officer at Embr. There’s another problem, too: It takes a lot more energy to cool something down than to heat something up. As a result, cooling devices are usually large, bulky, and loud—all because of the process of cooling is inherently inefficient.

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That’s why the Embr Wave, as well as Sony’s Reon Pocket, use a quirk of materials science called the Peltier effect to provide intense cooling sensations in a smaller form. In the 1830s, the French physicist Jean Charles Athanase Peltier discovered that if you run an electrical current across a junction between a metal and a semiconductor (the same material that you find in today’s electronics), you can create a cooling effect. If you run the current the other direction, you produce heat. Today, devices that use this effect, called thermoelectrics, can be found in everything from heated car seats to wine coolers. It’s how the Mars Rover was cooled, and it powers the cooling and heating on the International Space Station.

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The Embr Wave and the Reon Pocket both use the thermoelectric effect to generate cooling in a device that’s small enough to wear on your body. But thermoelectrics also requires a lot of energy. To make the Embr Wave more efficient, the startup’s team engineered the thermoelectric device to just target the temperatures that the human body responds to the best. Because temperature sensations are relative, the device doesn’t need to be anywhere close to freezing to feel cold—it just has to be a little cooler than the normal human body temperature. The device’s temperature rises and falls slowly, thanks to a proprietary algorithm that changes the temperature just enough to produce a cooling sensation while conserving battery. The Embr team says that you can run the device’s two- to three-minute cycles up to 50 times on a single charge.

The devices are also particularly useful for people with health conditions that are prone to overheating, [such as] multiple sclerosis, and for people engaged in certain occupations or activities, such as construction workers, athletes in certain sports, and other outdoor activities.