With so many devices to keep track of, it's easy to forget to charge your wearable. But what if your skin could power your smartwatch? Thanks to a team in China, this could actually happen. Scientists have developed a small, flexible device that converts heat from human skin into electrical power. Publishing their research in Cell Reports Physical Science, the team was able to power an LED light in real-time when worn on a wristband.
The device is a thermoelectric generator (TEG) that uses temperature gradients to create power. For their device, researchers use the difference between the warmer body temperature and the relatively cooler ambient environment to generate power. Traditional generators rely on the energy of motion to produce power. TEGs, however, don't have moving parts meaning they are maintenance-free. Unfortunately, TEGs are quite rigid – they can only withstand fewer than 200 instances of bending – not great for a wearable device.
The team tackled this issue by attaching the core electrical components to a stretchy and more adhesive polyurethane material. During testing, the device was able to withstand 10,000 instances of bending without affecting performance. The researchers also partially replaced the rare metal bismuth TEGs typically rely on with a magnesium-based material, which will cost less in large-scale production.
For the prototype, the team connected an LED to a TEG band measuring 4.5 in long and 1.1 in wide. The band was then wrapped around the wrist of someone whose body temperature measured at 92.9 degrees Fahrenheit in ambient environmental conditions. With the difference in temperature, the generator transformed the body heat and used it to light up the LED. The team believes that with the proper voltage converter, the generator can power smart wearables like smartwatches and pulse sensors.
It sounds promising, but the generator is still in the prototype phase. For now, you'll have to remember to charge your smart house before leaving the house.