As if graphene wasn't versatile enough already, researchers at the University of Arkansas have now found a way for the two-dimensional material to be used as a source of clean and potentially unlimited energy. By tapping into the random fluctuations of the carbon atoms that make up graphene sheets, the scientists can generate an alternating current strong enough to indefinitely power a wristwatch.
Graphene is a lattice of carbon just one atom thick, and its incredible strength and conductivity of electricity and heat mean it might soon start cropping up in everything from light bulbs to dental fillings, microphones, motorbike helmets, water filters, smartphone screens and even heat-dissipating shoes
The University of Arkansas researchers stumbled onto a new potential use for the material, when they set out to study the innate movements of graphene using a scanning tunneling microscope. In a phenomenon called Brownian motion, particles suspended in a fluid will randomly move in response to collisions with larger particles in the environment. In the case of a sheet of graphene, the atoms vibrate in response to the temperature around them, making sections of the linked carbon atoms rise and fall like waves on the ocean, sending ripples running through the material.
This motion could be tapped into as a source of energy, using a device the researchers have coined a Vibration Energy Harvester (VEH). The system starts with a sheet of negatively-charged graphene, suspended between two metal electrodes. When groups of atoms rise, the graphene curves and touches the top electrode, creating a positive charge, and when they fall they touch the lower electrode, which creates an alternating current.
Of course, being on the microscopic scale the amount of energy produced is tiny in the grand scheme of things, but it's all relative. Each individual ripple warps an area measuring 10 nanometers squared, and when that comes in contact with an electrode it produces 10 picowatts of power. That's barely a spark, but that energy increases exponentially when scaled up to patches of graphene measuring 10 microns wide (10,000 nanometers).
In all, those patches can generate enough energy to power a wristwatch, and since it occurs naturally and endlessly, the VEH could create a small battery alternative that theoretically never wears out and never needs charging. Next, the researchers plan to experiment with other materials besides graphene, and eventually the technique could be applied to other small electronic devices, such as pacemakers, hearing aids and other wearables.
The research was published in the journal Physical Review Letters.
Source: University of Arkansas
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