World's Smallest FM Radio Transmitter Built Using Graphene

A new nano-mechanical system capable of creating FM signals is, in effect, the world's smalls FM radio transmitter.

Created by researchers from Columbia University, the device is made out of graphene, a one-atom-thick carbon layer and the strongest material known to man. Graphene also boasts electrical properties superior to the silicon used to develop the chips found in today's electronics.

Such abilities make the material a convincing candidate for nanoelectromechanical systems (NEMS), the smaller version of microelectromechanical systems (MEMS), used in detecting vibration and accelerations. MEMS sensors are what enable smartphones and tablets to tell which way to rotate the screen when the device is tilted.

The graphene NEMS the team built had a frequency of about 100 megahertz, right in the middle of the FM band, which stretches from 87.7 to 108 MHz. Using low-frequency musical signals, including songs from an iPhone, they were able to modulate the 100 MHz carrier signal from the graphene, and then retrieve the musical signals again using a normal FM radio receiver.

"This work is significant in that it demonstrates an application of graphene that cannot be achieved using conventional materials," mechanical engineering Professor James Hone said in a statement. "And it's an important first step in advancing wireless signal processing and designing ultrathin, efficient cell phones. Our devices are much smaller than any other sources of radio signals, and can be put on the same chip that's used for data processing."

The graphene NEMS are not designed to replace conventional radio transmitters, according to the researchers, but instead to be applied to wireless signal processing.

"Due to the continuous shrinking of electrical circuits known as 'Moore's Law', today's cell phones have more computing power than systems that used to occupy entire rooms," engineering Professor Kenneth Shepard explained. "However, some types of devices, particularly those involved in creating and processing radio-frequency signals, are much harder to miniaturize.

"These 'off-chip' components take up a lot of space and electrical power. In addition, most of these components cannot be easily tuned in frequency, requiring multiple copies to cover the range of frequencies used for wireless communication."