The heat too much for you? What if you had your own personal thermostat?
In September 2017, Embr Labs introduced to the public a product that could do just that. The Wave, which looks like an Apple Watch worn on the inside of the wrist, promised to regulate the wearer's temperature. A button turns it hotter or colder, and when it heats up or cools your inner wrist, you feel as if you turned on a personal thermostat only for you.
Using a UC Berkeley team's research as a starting point, three engineers built a prototype Wave that summer. They tested it on friends, family, and strangers, who came back with unanimous feedback: The gadget made them feel noticeably warmer or cooler.
The Wave doesn't change your core temperature. It's all about perception. Think of holding a hot cup of tea on a cold day or holding a glass of ice-cold water on a hot day. You know you're not doing much to actually heat up or cool down your body, but it makes you feel disproportionately warm or cool all over. That's because in cold conditions, the local temperature of your hands and feet dictate how comfortable you feel, says Dr. Hui Zhang, a research scientist at UC Berkeley's Center of the Build Environment. It was her research the Embr Labs' founders discovered back in 2013 and which inspired the Wave prototype. If your hands or feet are cold, your whole body will feel cold, so Zhang says warming them up first is the fastest way to feel warm. In warm conditions, cooling the head is the most effective spot, but it would be awkward to mount a device there. The next-best spot for cooling: the wrist.
Zhang's preexisting research in mapping the entire body's sensitivity to heat and cooling pinpointed the wrist as having a high density of temperature-sensitive nerve endings, called thermoreceptors, that are highly responsive to any temperature change. The Wave is designed to be worn on the inner wrist, but some people wear it on the outside of their wrist like a watch and it still works.
The Wave has seven temperature levels, and Zhang's experiment used the more moderates levels three and five. After three minutes of cooling, testers averaged feeling 5.8 degrees cooler; after three minutes of heating, they averaged feeling 4.6 degrees warmer. “It's very sudden, and pretty strong,” she recalls of using the Wave herself.