The Internet of Things Is One Step Closer to Being Powered by Wifi

The internet of things is probably going to be full of tiny little scavengers.

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Aug 6 2014, 10:00am

University of Washington

The Internet of Things is coming—or already here, depending on who you ask—and it's going to be hungry for power. Those "things" need energy, after all, and most of us only have so many power outlets and so much time (and patience) to spend recharging devices on a regular basis.

That fact hasn't escaped a number of researchers in a position to do something about it, some of whom are working to build ever smaller, longer-lasting batteries. Others, like a team at the University of Washington, have been developing wireless devices that don't require any batteries at all. 

As Motherboard reported last year, the group has already made considerable progress with devices that can wirelessly communicate with one another. Now, they've made a key step forward and developed prototype devices that can each connect to the internet, batteries not included.

As before, the battery-free devices get their power by harvesting small amounts of energy from readily available radio frequency sources like TV broadcasts and wireless signals. The hold-up that previously prevented the devices from connecting to the internet is that the amount of power required to use a regular wifi network can be up to four times as much as they're able to harvest out of the air.

To get around that, the group has devised a different, decidedly novel approach to communicating over wifi. Instead of generating signals to communicate directly over a network, the devices use what the researchers call a wifi backscatter tag to modulate the wifi channel itself, by either reflecting or not reflecting its signals. Those changes can then be detected by a laptop or smartphone, which can in turn decode the data.

"You might think, how could this possibly work when you have a low-power device making such a tiny change in the wireless signal," associate professor Joshua Smith explained in a statement announcing the findings, "but the point is, if you're looking for specific patterns, you can find it among all the other wifi reflections in an environment."

The group also notes that the whole system operates using off-the-shelf wifi gear, which they hope will speed up its adoption. They see it finding its way into everything from sensors and wearable devices to everyday items around your house—and, not surprisingly, they already have plans to start a company based on the technology.

It's still a bit early to get too excited about all of your devices using the technology, though. Right now, data transmission is limited to a rate of one kilobit per second and a range of two meters, the latter of which the researchers hope to soon boost to 20 meters. (We are talking about a process that still vaguely resembles a magic trick here, remember.)

If the internet of things is to be full of tiny little scavengers, however, it likely won't just be devices harvesting ambient RF signals. Other researchers have also been hard at work developing a variety of different methods to leech out just enough power from any source they can.

Just last month a team of MIT researchers published findings that suggest small amounts of power could be harvested from water droplets jumping from surfaces during condensation, while another group from the university previously developed a chip that can harvest energy from light, heat and vibrations to provide a more stable power source for things like environmental sensors in remote locations. And that's to say nothing of more common sources like kinetic energy, which is already being harvested and put to use by some devices.

The future, it is hungry.