Wearables that have weaved their way into everyday life include smart watches and wireless earphones, while in the healthcare setting, common devices include wearable injectors, electrocardiogram (ECG) monitoring patches, listening aids, and more.
A major pain point facing the use of these wearables is the issue of keeping these devices properly and conveniently powered. As the number of wearables one uses increases, the need to charge multiple batteries rises in tandem, consuming huge amounts of electricity.
A research team, led by Associate Professor Jerald Yoo from the Department of Electrical and Computer Engineering and the N.1 Institute for Health at the National University of Singapore (NUS), has developed a technology that enables a single device, such as a mobile phone placed in the pocket, to wirelessly power other wearable devices on a user’s body, using the human body as a medium for power transmission.
The team’s novel system has an added advantage—it can harvest unused energy from electronics in a typical home or office environment to power the wearables.
The NUS team designed a receiver and transmitter system that uses the human body as a medium for power transmission and energy harvesting. Each receiver and transmitter contains a chip that is used as a springboard to extend coverage over the entire body.
A user just needs to place the transmitter on a single power source, such as the smart watch on a user’s wrist, while multiple receivers can be placed anywhere on the person’s body. The system then harnesses energy from the source to power multiple wearables on the user’s body via a process termed as body-coupled power transmission. In this way, the user will only need to charge one device, and the rest of the gadgets that are worn can simultaneously be powered up from that single source. The team’s experiments showed that their system allows a single power source that is fully charged to power up to 10 wearable devices on the body, for a duration of over 10 hours.
As a complementary source of power, the NUS team also looked into harvesting energy from the environment. Their research found that typical office and home environments have parasitic electromagnetic (EM) waves that people are exposed to all the time, for instance, from a running laptop. The team’s novel receiver scavenges the EM waves from the ambient environment, and through a process referred to as body-coupled powering, the human body is able to harvest this energy to power the wearable devices, regardless of their locations around the body.
This paves the way for smaller, battery-free wearables
read the paper in Nature at http://dx.doi.org/10.1038/s41928-021-00592-y
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