A woman named Meredith Perry was studying astrobiology at the University of Pennsylvania when she made an interesting discovery that allows portable electronic devices like laptops and cell phones to be charged wirelessly using ultrasound. The tech she created takes electricity and converts it into ultrasound that can be sent through the air to a receiver.
The receiver on the other end captures the ultrasound and turns it back into electricity. Recently the company that Perry founded, called uBeam, created a fully functional prototype of the tech, and plans to turn it into a product for consumers.
With this tech, a user could be on their phone and moving around a room freely while the device is charging. The uBeam transmitter would be no more than 5mm thick and receivers for converting the sound into electricity would also be thin. The tech being used can also be used to send secure data as well. One drawback of the tech is that power can't be transmitted through walls; a transmitter is needed for each room.