The team laid sheets of graphene across a supportive copper grid and observed the changes in the atoms’ positions using a scanning tunnelling microscope. While they could record the vibration of atoms in the graphene, the numbers didn’t fit any expected model and they couldn't reproduce the data they were collecting from one trial to the next.
They then began searching for a pattern by changing the way they looked at the data. “We separated each image into sub-images,” Prof Thibado explained. “Looking at large-scale averages hid the different patterns. Each region of a single image, when viewed over time, produced a more meaningful pattern.”
Patterns of small, random fluctuations combining to form sudden, dramatic shifts are known as Lévy flights. While they've been observed in complex systems of biology and climate, this was the first time they’d been seen on an atomic scale.
By measuring the rate and scale of these graphene waves, Prof Thibado figured it might be possible to harness it as an ambient temperature power source. By placing electrodes to either side of sections of the graphene.
By Prof Thibado's calculations, a single 10 x 10μm piece of graphene could produce 10μW. Given that more than 20,000 of these squares could fit on the head of a pin, Prof Thibado said a small amount of graphene at room temperature could feasibly power a device like a wrist watch indefinitely.
This would have significant implications for the Internet of Things. A self-charging, microscopic power source could make everyday objects into smart devices, as well as powering more sophisticated biomedical devices such as pace-makers, hearing aids and wearable sensors.
Prof Thibado said that these applications still need to be investigated and he is working with scientists at the US Naval Research Laboratory to research the concept further. He has also taken the first steps toward creating a device, called a Vibration Energy Harvester, or VEH, to turn this movement into electricity.
