For a year and a half I had the chance and the luck of working among great minds at Columbia university in nanofabrication and interesting mechanical engineering-related projects. I was never myself involved in any graphene-related projects, but I did meet quite a few PhD students and faculty working with this fascinating material. Last night, when reading the IEEE Spectrum Magazine, I was happy to see some of these people I met featured with a very cool story.

A team under James Hone and Kenneth Shepard at Columbia University has built the tiniest FM transmitter in the world, which is made of graphene.

From the IEEE Spectrum Magazine:

Many research groups have built graphene transistors that could be used in future RF circuits such as signal processors. Hone and his colleagues decided to test a different radio application for graphene, by building a moving, vibrating, electromechanical device. The team reckons that such graphene-based nanoelectromechanical systems (NEMS) could be more compact and easier to integrate onto chips than silicon MEMS and quartz devices, which are used today to pick up and filter RF signals in smartphones and other gadgets.

To build a graphene transmitter, the team suspended a 2-4 micrometer-long strip of graphene above a metal electrode. By applying a voltage to the electrode, they could draw the strip of graphene down. The resulting strain altered the strip’s resonant frequency, tuning it up much as you might tighten a guitar string. By altering the voltage on the gate, the team found they could use the graphene device to generate a frequency-modulated electromagnetic signal. In a paper published this week in Nature Nanotechnology, they report the device could transmit radio signals at 100 MHz, right in the center of the FM band.

It is very interesting how the graphene acts as an oscillator, which moves and vibrates, providing a more compact, small and easier to integrate form than quarz oscillators. Very cool stuff. Specially the demo of the project, by transmitting Gagnam Style with the graphene FM transmitter and playing it on a normal FM radio. You can listen to the recording of the experiment here.

You’ll notice a fair amount of static in the audio clip. That’s partly because the graphene oscillator is quite sensitive to electrical noise: a small voltage on the gate electrode can dramatically shift the frequency, Hone says. The team didn’t add insulation in order to optimize their set-up for this demonstration. “We were also trying to operate at 100 MHz, right smack in the middle of the FM spectrum, where you can pick up a lot of FM signals,” he adds.

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