Researchers at Carnegie Mellon University (USA) have developed Power-over-Skin technology, which allows wearable devices to be powered by human body energy without the use of batteries.
In the research work indicated the human body is particularly efficient at generating RF energy at 40 MHz. Harnessing this energy through a «wearable receiver» provides power without the use of invasive techniques. Researchers have focused most of their efforts on optimizing these receivers to ensure acceptable size, weight, form factor, and power efficiency. The receiver can potentially be placed anywhere, and because it is capacious, it can even operate through clothing — theoretically creating the possibility of integration into a smartphone.
The researchers demonstrated the technology on several prototypes: A Bluetooth ring with a joystick, a medical patch for health monitoring, and a solar radiation sensor with a display. In the future, this technology may be used for VR/AR headsets.
The elimination of batteries will make wearable devices lighter and thinner. It will also reduce the need for rare earth metals for battery production.
Provided there are no negative side effects, this has the potential to be revolutionary. It could power anything from a relatively simple watch to a host of other wearable devices, including fitness trackers and medical devices. However, the devices would need to consume little power – a full-fledged GPU or CPU would not work from the body’s RF radiation.
The research paper compares the basic idea to mechanical watches, which had a self-winding mechanism and used hand movements to wind the mainspring. They have been replaced by more accurate and cheaper quartz movements with batteries. Now there is a more sophisticated way to get energy from the user’s body.
At the same time, the location on the body and the transmission distance are crucial. The team investigated four transmitter locations — right foot sole, abdomen, left wrist, and face, which are potentially useful for AR/VR headsets. Each transmitter had six receiver locations — right ankle, back of the neck, chest, left and right biceps, and left index finger — typically where wearables are frequently used. The highest recorded power was from the test device with the shortest distance between the transmitter and receiver, averaging 1.53 mW, and the lowest recorded power was 5.3 µW. Transmission through clothing, while possible, reduced efficiency.
Source: tomshardware