Scientists have invented a device that collects errant microwave signals from the air and converts them into electrical current capable of charging a cell phone.

Researchers at Duke University said the device has nearly the same efficiency as solar panels.

The device consists of a series of five fiberglass and copper conductors wired together on a circuit board to convert microwaves into 7.3V of electricity. USB chargers for small electronic devices provide about 5V.

"We had been getting energy efficiency around 6 to 10 percent, but with this design we were able to dramatically improve energy conversion to 37 percent." said engineering student Allen Hawkes.

The small amount of energy generated from these signals might power a sensor network in a remote location or remote environments such as a mountaintop or in a desert.

Future versions of this device will be able to harvest signals from a range of sources such as satellite, sound or Wi-Fi .

The invention that provides a simple and inexpensive approach to electromagnetic power harvesting was created by undergraduate engineering student Allen Hawkes, graduate student Alexander Katko and lead investigator Steven Cummer.