The dream of wireless power is coming true, according to research from the University of Washington in Seattle, where a team of engineers led by Vamsi Talla has found a way to power a wireless security system, using juice transmitted by Wi-Fi only, just as Nikola Tesla predicted.
Power is one of the great stumbling blocks of the IoT. Without it, there is no IoT. The problem arises in that wired power is limited in range and expense, and batteries are too unreliable, short-lived (although that’s changing) and expensive. Wireless power could solve those problems in one fell sweep.
Talla and company have figured out how to send power wirelessly to devices, although only over a few feet so far. The solution uses existing tech and Wi-Fi chip sets and they call it PoWi-Fi, or power over Wi-Fi. The concept came from Talla’s idea that if Wi-Fi antennae can receive data, why not energy, too?
Then measuring how much power comes over the air, it can approach around 300 millivolts, which is the operating threshold, and more than enough to power most sensors indefinitely. One problem they found was that Wi-Fi routers usually only broadcast in bursts of information, and a device would need a constant flow of juice to stay viable. To solve that, the crew programmed the routers to broadcast noise when it’s not sending actual information, and use untapped Wi-Fi channels to keep from interfering with the intelligible data stream.
In the end, the team was able to operate a temperature sensor from about 20 feet away from the router with no other source of power. Of course, if this is to be viable in the larger IoT, the ranges will need to increase, but that’s just a matter of time. In terms of available juice, that seemed to be no problem at all. They powered up an Omnivision VGA camera that needs 10.4 milliJoules of energy per picture it captures, and that was no problem. The published research said that the camera worked battery-free at about 15 feet from the router and was able to capture an image about every 35 minutes. The router was able to keep the camera powered up even through a brick wall.
The team charged a variety of batteries over Wi-Fi, and even did real-world tests in urban areas with quite impressive results. Click here for the full paper.
It’s early to tell, but this might just be the beginning of the end of the wired age. And it’s about time. To get some more insight into what’s coming for Wi-Fi technology and the IoT, join us at IoT Evolution Expo in Las Vegas, from August 17 to 20.
Take that, Edison.
Edited by
Dominick Sorrentino
