How to charge your connected watch without ever removing it? An American research team has found a solution as ingenious as it is experimental: using human skin as a conductor.
- Researchers have developed a prototype capable of recharging a connected watch using an electrode, via human skin, which serves as a conductor of electricity.
- The process, which is completely painless, could make it possible to continuously recharge a connected watch or a fitness tracker at very low power.
Since their appearance on the market about ten years ago, connected watches, or “smartwatches”, have revolutionized the world of high-tech. Not only able to run mobile applications, they have also become the faithful companions of health-conscious people by measuring all their physical activity: heart and respiratory rate, pedometer, calories and even quality of sleep.
But there is one problem that smartwatch makers have so far failed to solve: that of charging. To be able to be recharged, these portable and wireless devices are often disconnected from our body during the night. What prevents them from noting the quality of sleep and its characteristics, which “contain a lot of important information about the health status of patients”, underlines Sunghoon Ivan Lee, assistant professor at the College of Information and Computer Sciences of the university. of Massachusetts Amherst and director of the Advanced Human Health Analytics Laboratory.
But this researcher may have found a solution to this problem. Partnered with Jeremy Gummeson, a wearable computing engineer at UMass Amherst, he sought a way to continuously charge these devices on the body so they could monitor the user’s health 24/7. .
Use the skin as a conductor of electricity
The solution they found is none other than to use human skin as a conductive material. “Then we can get people to do things like sleep tracking because they never have to take their watch off to charge it,” says Professor Lee.
In an article published in the Proceedings of the ACM on Interactive Mobile, Wearable and Ubiquitous Technologiesresearchers explain how the technology uses human tissue as a medium for energy transfer. “In this device we have an electrode that couples to the human body, which we can think of as the red wire, if we think of a traditional battery with a pair of red and black wires”details the scientist.
The classic black wire is established between two metal plates integrated into the connected watch, and another instrumented everyday object (laptop, car, etc.), through which the energy passes.
This prototype was tested with 10 people in three scenarios in which the individuals arm or hand came into contact with the energy emitter – either while working on a desktop keyboard or laptop, or while holding the steering wheel of a car.
By sending 0.5 to 1 milliwatt (mW) of direct current through the device worn on the wrist and using the skin as a transfer medium, the researchers were able to charge the watch, without this small amount of electricity being dangerous to health.
“You can consider the amount of energy transmitted by our technology to be roughly comparable to that transmitted by the human body when standing on a body composition scale, which poses minimal health risks”says Professor Gummeson.
Absolutely painless charging
According to the researchers, contact with the energy emitter is absolutely painless because “it is far beyond the range of frequencies that humans can perceive”.
The prototype currently doesn’t produce enough power to continuously run a fancy device like an Apple Watch, but it could support ultra-low-power fitness trackers like Fitbit Flex and Xiaomi Mi. -Bands.
The team is now working on improving the energy transfer rate in smartwatches. “We imagine that in the future, by further optimizing the energy consumed by wearable sensors, we can reduce and eventually eliminate charging time.”concludes Professor Gummeson.
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