Charging devices through the air

uBeam is using ultrasound waves to wirelessly charge your phone. The technology behind uBeam is something that's unprecedented. It converts electricity to inaudible sound waves, which travel through the air. The sound waves get converted back to electricity, which then charges up your devices. In order to work, the uBeam system needs a charger (which can be attached to a wall) and a receiver (which gets put on each device you want to charge).

They've developed a powerful and intelligent ultrasonic transmitter that beams high intensity ultrasound through the air. The ultrasound in the air hits a receiver, which can be in the shape of a case around an electronic device or can be embedded within a device. The receiver vibrates in response to the sound at a frequency too fast for people to feel, and then converts that vibration into electrical power.

The technology has one caveat: it can't beam sound waves through walls.