Your Wi-Fi router already brings you Netflix and cat pictures, but someday it might become even more important to your life. A group of researchers from the University of Washington were able to send energy from a Wi-Fi router to low power electronics from up to 28 feet away, without interfering with the router’s – and neighboring routers’ – ability to transmit data. They call their technology Power over Wi-Fi (PoWiFi).
Using Atheros chipsets, the researchers made several PoWiFi routers that worked as normal but also sent meaningless packets of data over multiple 2.4Ghz channels. They programmed these routers to send these “unintrusive power traffic” only when the router isn’t sending data to connected devices. They then built four low power devices: a temperature sensor, a camera, a coin battery charger and the AA battery charger shown above.
Each of those devices was equipped with a harvester that converted the radio waves from the router – whether it contained actual data or the aforementioned power traffic – into direct current voltage, which was then boosted to a usable voltage with a DC-DC converter. In their tests, they were able to operate the camera up to 17 feet away, the temperature sensor up to 20ft away and the battery chargers up to 28 feet away from their router.
Using a 2.4Ghz antenna and their harvester, the researchers also built a wireless USB charger (top image). It was able to charge a Jawbone UP 24 from 0% to 41% in 2.5 hours while placed a couple of inches away from their router.
Finally, the researchers tested how their routers fared in real world settings. They asked six different households to use a PoWiFi router for their usual Internet activities for a few days. They also installed harvester-equipped temperature sensors 10 feet away from each router. Their results showed that the routers performed well, adjusting for client traffic both within the households and from neighboring routers while still sending enough power to the temperature sensors.
The researchers hope that their technology will lead to battery-free sensors and mobile devices that are continuously powered by Wi-Fi routers. Check out the researcher’s full paper at Cornell University Library’s arXiv.