Electronics

Two-dimensional antenna converts Wi-Fi signals into electricity

Two-dimensional antenna conver...
Engineers have developed a new two-dimensional device that can convert Wi-Fi signals into electricity
Engineers have developed a new two-dimensional device that can convert Wi-Fi signals into electricity
View 1 Image
Engineers have developed a new two-dimensional device that can convert Wi-Fi signals into electricity
1/1
Engineers have developed a new two-dimensional device that can convert Wi-Fi signals into electricity

Wireless charging is increasingly common in phones and other devices, but it's still held back by a very short range – usually the device needs to sit on top of a charging pad, which cancels out some of the benefits of going wireless. In a new step towards truly wireless charging, engineers have developed an ultra-thin device that captures Wi-Fi signals and converts them into electricity.

The new system is based on existing devices called rectifying antennas, or rectennas. These capture AC electromagnetic waves in the air – such as Wi-Fi signals – and convert them into DC electricity. But most of them are rigid and, being made with silicon or gallium arsenide, are best suited to powering small electronics. So the team on the new study set out to develop a new rectenna that's flexible enough to be scaled up to much larger sizes.

For the new design, the team made the rectifier – the component that converts the current – out of molybdenum disulfide (MoS2). This semiconducting material measures just three atoms thick, making it extremely flexible while still holding its own in the efficiency department. The team says the MoS2 rectifier can capture and convert up to 10 GHz of wireless signals with an efficiency of about 30 percent. That's much higher than other flexible designs, and the researchers also say it's faster.

That said, it doesn't quite stack up against other rectifiers, which can reach efficiencies of up to 60 percent. It's also generating a relatively small amount of electricity, producing about 40 microwatts from about 150 microwatts of Wi-Fi power. Although that isn't much, it should be enough to power small wearable or medical electronic devices, removing the need for batteries.

The team hopes that these disadvantages will be outweighed by the other benefits of the new design, including its flexibility and scalability.

"What if we could develop electronic systems that we wrap around a bridge or cover an entire highway, or the walls of our office and bring electronic intelligence to everything around us?" says Tomás Palacios, co-author of the study. "How do you provide energy for those electronics? We have come up with a new way to power the electronics systems of the future – by harvesting Wi-Fi energy in a way that's easily integrated in large areas – to bring intelligence to every object around us."

Next up, the team is planning on improving the efficiency and building more complex systems.

The research was published in the journal Nature.

Source: MIT

10 comments
mhemedh
I concern about how this MOS2 rectifier can capture wi-fi/radio signals? Is it capable to capture any wi-fi/radio signals around us & converts it to DC power?. So it captures only the EM waves without any interruption or affecting the services/quality to wi-fi sources. Also does it deal only with wi-fi signals as you mentioned it can capture up to 10 Ghz & this sure falls in radio spectrum. Also did this rectifier introduce to the market? Are there will known vendors/suppliers have started the manufacturing processes?
myale
Okay now I remember times when people used to put large masts in their gardens to use old communications or listen into long waves and these used to cause dead spots for other people as they just took all of the signal - would the same not happen with these if we have everything literally using all of the available EM.
Paul Briers
It looks like the stickers I used to get off ebay to improve the signal on my Nokia 7110.
AlexanderJoshuaDavis
And then think about what this radio-frequency radiation is doing to our bodies... especially children's. Cancer rates and infertility are bound to soar even higher in the wake of the "5G" (actually 6ghz all the way to 100ghz being unlocked!) network roll-out globally.
SteveMc
There’s no such thing as dead spots as you describe. Apparent dead-spots are actually saturation. Usually caused by higher power transceivers bleeding over your transmission or reception. Further complicated by harmonic interference. This was a well known problem during the good old CB days of the 70’s/80’s when everyone tried to outdo each other with high powered amplifiers and oversized antennae. Was great fun tho! :)
CarolynFarstrider
If pursued to its logical conclusion, do we not seem to have a perpetual motion machine here? And perpetual motion machines are nonsense. WiFi and radio signals have to be generated somewhere, using quantities of energy, renewable or otherwise, to do so. We then capture it back at relatively low efficiency. But we could cover large areas with these 'fabrics', so apparently generate quite a bit of energy with which to charge other devices (leaving aside the issues of harvesting and affecting other people's signals). This is surely one of the most inefficient ways of managing energy, at scale, that one could imagine. Tiny devices, in specialist applications, possibly. But as a routinely used system for recharging, absolutely not.
Paulinator
As a kid I made a crystal radio that powered little ear-buds from the energy captured out of the ether. Granted, I had a 25 foot long antenna stretched across the garage roof.
jocco
I am surprised at how little people seem to know about radiation. Do you think that solar cells are going to use up the sun's solar radiation? I am waiting for somebody to invent a radiation collector that will collect all types of solar system radiation night or day.
Simon Redford
I don't know much about RF power transmission, but surely if a lot of devices are taking power from a signal, then more power must go in? I took a look at https://en.wikipedia.org/wiki/DBm and see that the maximal received signal power of wireless network (802.11 variants) is 100 µW (-10dBm) and typically considerably less. Have I misunderstood this or is there insufficient signal power to provide the device power described in this article, or conversely, would far higher Wi-Fi power (and close proximity) be required?
Martin Winlow
From the comments already on this article, I can see I am going to be disappointed anticipating some informed debate on the subject but I'll comment nevertheless... Wifi transmission power is TINY and the power required to recharge a mobile device, whilst small in the greater scheme of things, is HUMUNGOUS in comparison to wifi power. Even if the antenna were100% efficient (whatever that means), there would *never* be anywhere near enough power from wifi transmissions alone to even *hope* to get a meaningful charge from such a system.