Although you are just beginning to take advantage of 5G wireless technology, researchers around the world are already working hard for the future: 6G. One of the most promising breakthroughs in 6G telecommunications is the ability to communicate in visible light (VLC), which is similar to a wireless version of fiber optics and uses flashes of light to transmit information.

Now, a group of researchers at the University of Massachusetts Amherst announced that they have found a low-cost, innovative way to harvest VLC waste energy using the human body as an antenna. This wasted energy can be recycled to power large numbers of wearables and possibly even larger electronics.

“VLC is pretty simple and interesting,” said Ji Xiong, professor of information and computer science at the University of Massachusetts Amherst and senior author of a paper describing the work.

“Instead of using radio signals to transmit information wirelessly, it uses light from LEDs that can turn on and off a million times per second.”

Part of VLC’s appeal is that infrastructure is already ubiquitous: our homes, cars, streetlights, and offices are illuminated by LED bulbs that can also transmit data.

“Anything with a camera, like our smartphones, tablets, or laptops, can be a receiver,” says Xiong. Previously, Xiong and first author Minghao Cui, a graduate student in the Department of Information and Computer Science at the University of Massachusetts Amherst, showed that there is a significant amount of energy “leakage” in VLC systems because LEDs also emit “side channel radio frequency”. signals” or radio waves.

If this leak of radio frequency energy could be collected, it could be used. The team’s first task was to design an antenna out of twisted copper wire to collect the leaky RF signal they were doing. But how do you maximize the energy harvest?

The team experimented with various design details, from the thickness of the wire to the number of bends, but they also realized that the effectiveness of the antenna depends on where the antenna touches it. They tried to put the coil on plastic, cardboard, wood and steel, as well as touch walls of different thicknesses, on and off phones and laptops.

And then Cui had the idea to see what would happen when the coil came into contact with the human body. It quickly became clear that the human body was the best medium for improving the coil’s ability to collect RF energy leakage ten times greater than a single bare coil.

After many experiments, the team found the “Bracelet+”, a simple coil of copper wire worn as a bracelet on the upper forearm. While the design can be adapted to be worn as a ring, belt, anklet or necklace, the bracelet seems to offer the right balance between energy harvesting and wearability.

“Design is cheap – less than fifty cents,” say the authors, whose papers won the prestigious Best Paper Award at the Information Machinery Association Embedded Networked Sensor Systems conference. “However, bracelet+ can reach microwatts, which is sufficient to support many sensors, such as body-based health monitoring sensors, which require very little power to operate due to their low sampling rates and long sleep modes.”

“Ultimately,” says Xiong, “we want to be able to collect waste energy from any source to power future technologies.”