Wi-Fi Router Battery Charging wirelessly
The Asus RT-AC68U router was used by researchers at the University of Washington to demonstrate how it could wirelessly charge cameras, sensor and batteries while maintaining its Wi-Fi signal.Asus

Researchers have discovered a way to harness the energy being produced by your wireless router in order to charge devices including cameras, rechargeable batteries, and temperature sensors.

Unlike other versions of this technology, called Power-over-Wi-Fi or PoWi-Fi, the solution invented by a PhD student named Vamsi Tallaand his team of researchers in Sensor Systems Lab at University of Washington, will also allow you to continue using the Wi-Fi signal from the router.

In his paper describing the research - entitled Powering the Next Billion Devices with Wi-Fi - Talla says why his solution could be so important:

"There is increasing interest in the Internet-of-Things where small computing sensors and mobile devices are embedded in everyday objects and environments. A key issue is how to power these devices as they become smaller and more numerous; plugging them in to provide power is inconvenient and is difficult at large scale."

Talla realised that Wi-Fi routers, which are located in homes and businesses all around us, were transmitting energy signals which were similar to the operating voltages required by many of today's consumer electronics.

The problem was that the signals were intermittent and broadcast in bursts across different frequencies. The solution was relatively simple, with the researchers modifying normal routers to broadcast noise when a channel was not being used to send data.

Firmware update

This allowed them to send a constant - albeit low - amount of energy through Wi-Fi signals which was enough to charge temperature sensors which were 20 feet away, a camera that was 17ft away and some rechargeable batteries which were 28ft away.

This solution means that virtually all routers in use today could be modified with a simple firmware update to work with this system.

Both the small surveillance camera and the temperature sensor are battery free, meaning that manufacturers of connected, smart home devices could use this system to create ever smaller devices as part of the Internet of Things revolution.

The system was also used to recharge "nickel–metal hydride and lithium–12 ion coin cell" batteries meaning there is the potential for this to be used to charge everything from your smartphone to your laptop.

Limitations

The limitations of what can be powered by this system is not down to the technology, but down to the fact that the routers tested by Talla and his team are limited to one-watt power output by the Federal Communications Commission (FCC) though there appears to be no reason for this restriction.

There are already products on the market which send power through the air using RF signals but there are two key areas where Talla's solution has an advantage.

The first is the fact that with a firmware update to existing routers, the vast majority of routers in use today can be converted to send power in this way, while products like Energous require dedicated hardware to work.

Secondly, previous solutions have been unable to get both power and Wi-Fi to work at the same time, but Talla's solution sees minimal slowdown to the data rates broadcast by the routers.

Looking at how his invention could be utilised in the future, Talla suggests we could see public Wi-Fi hotspots converted into Wi-Fi + Charging hotspots, to charge wearables like fitness trackers from Fitbit and Jawbone - though this would require new hardware from those manufacturers.