Researchers at the University of Washington propose wifi can do more than simply wirelessly connect devices to networks and the internet-- it might also be able to charge device through "Power over Wifi" (PoWiFi).
The system consist of two components, namely an access point (or router) and specially-built sensors. The access point features custom software allowing it to simultaneously act as power delivery source and wifi router, while the sensors harvest RF power and convert it into DC power.
Admittedly wifi signals carry a limited amount of power-- 1W to be precise, making it unsuitable with smartphones but still ideal for small connected devices. As such the researchers have used PoWiFi to power a small camera located 5m away from a router, as well as charge a fitness charger and temperature sensors.