A group of Columbia University Ph.D. candidates has developed a way to use a small sheet of graphene as a tunable resonator in a filter that is very small, low powered and easily tunable. This device could enable more versatile wireless circuits that would operate at many different frequencies while also able to integrate with existing silicon chip technology. The research earned the Columbia team a Qualcomm Innovation Fellowship award and an accompanying $100,000 prize.
The device is essentially a sheet of carbon—about 10,000 times thinner than human hair— that is suspended like a bridge between two electrodes. When electrical signals are applied to a third electrode, located underneath the graphene sheet, only the signal at a particular frequency (the resonant frequency or RF) can make the graphene vibrate. This vibration changes the electrical properties of the graphene sheet and in effect amplifies the desired signal and blocks out interfering signals and noise. The device is especially unique because the resonant frequency of the suspended graphene can be tuned electrically by as much as 400 percent, in contrast to existing technologies that are only tunable by 1 percent.
