RCA is launching a charger which works on thin air, by drawing its power from Wifi signals.
The phone-sized Airnergy device is described by RCA as a Wifi Hotspot Power Harvester. It converts the ambient Wifi signals floating around in the air into energy, which it stores in its own lithium battery. It can then be plugged into a device which needs charging via a mini-USB connector.
The user doesn't need to be online - just being within range of a signal is enough.
The charge rate depends on the number of Wifi sources around, signal strength and the charger's distance from the signal source. Clearly, it's not going to produce a huge amount of power, even in an area with a strong signal, but the company claims it can charge a Blackberry from 30 percent to 100 percent in less than two hours.
The device - which looks rather like a standard dongle - is expected to go on sale later this year for about $40. RCA is also looking at incorporating it into batteries that could be used in devices themselves, so that gadgets could charge themselves without any user intervention.