A team of Columbia Engineering researchers, led by Mechanical Engineering Professor James Hone and Electrical Engineering Professor Kenneth Shepard, exploring the properties of graphene have demonstrated a new electro-mechanical resonant component.
The resonator’s structure consists of a 2-4 micrometer long strip of graphene suspended over a metal gate electrode. The strip of graphene has a natural resonance governed by its physical dimension and is used in the demonstration as the frequency determining element in an RF feedback oscillator circuit. Applying a voltage to the gate electrode stresses and deflects the graphene strip changing its resonant frequency. The team applied baseband audio and tones to the gate electrode to produce a 100 MHz FM signal.
This tiny resonant element looks set to dramatically reduce the size of mobile RF equipment. Traditional discrete quartz crystals have a relatively large PCB footprint but this resonator design will allow it to be integrated within the chip. To test it under extreme conditions the team played the now classic K-pop song ‘Gangnam Style’ on an iPhone and fed it into the graphene FM oscillator. It didn’t break although many wished otherwise. They were able to pick up the signal on an FM radio that Hone had brought in from home.