In 1965, Intel co-founder Gordon Moore observed that as electronic devices such as cell phones and cameras decreased in size, their processing power and memory capability grew exponentially. His conjecture, which soon became known as “Moore’s Law,” has become one of the driving forces behind technological advancement. Over the past few decades, scientists and inventors have continually defied the limits of technology. We are all too accustomed to ultra-thin cell phones and super fast computers, the likes of which our grandparents and maybe even parents never could have imagined.
You might wonder if circuits and microchips will ever become so small that we won’t be able to make anything smaller. While technological innovation is indeed slower than it was at the end of the 20th century, it does not seem like we have reached that limit quite yet. Two professors at Columbia University, James Hone and Kenneth Shepard, have created the world’s smallest FM radio transmitter — a nanoelectromechanical system (NEMS) made out of graphene — that could shrink our cell phones even more.
Graphene is a single layer of carbon, the same element that makes up diamond or the “lead” in a pencil. The atoms in graphene are arranged in a honeycomb lattice, which can stretch mechanically to create a radio signal. Changing how much the lattice is stretched changes the frequency of the radio signal, producing a frequency modulated (FM) wave. Furthermore, the lattice is the strongest material known to man, and has electrical properties that make it an ideal material for small, durable electronic components such as NEMS. These are miniaturized versions of microelectromechanical systems (MEMS); the most commonly known ones are responsible for rotating tablet and phone screens based on the device’s orientation.
Hone and Shepard’s team harnessed these properties to build a specific graphene NEMS known as a voltage controlled oscillator. This system was able to generate a FM signal with a frequency of about 100 hertz, which is in the middle of the FM radio band. They observed that the signal from the graphene could change the frequency of low frequency musical signals, which could then be detected by an FM radio receiver as ordinary as a car radio or a walkie talkie.
The small size and versatility of the graphene NEMS means that it could replace the cell phone “off-chip” component, which is responsible for creating and processing radio signals. Such components are named because they are not directly integrated into the rest of the phone. Present day off-chip components are rather large and can use a lot of electrical power.
Like any other new technology, the system still has its bugs. Hone and Shepard are currently working to reduce unwanted signals produced by the graphene NEMS and integrate the system into silicon integrated circuits and microchips. This would make the device even smaller.
We won’t be seeing graphene NEMS in our cell phones anytime soon, but chances are the technology will eventually become something we take for granted.
