Researchers Harness Brownian Motion in Graphene to Produce "Clean, Limitless Energy" for Electronics

Physicists from the University of Arkansas have created a circuit that they claim can capture "clean, limitless, low-voltage power" suitable for embedded systems including sensors and other small devices — using an approach previously believed to be impossible.

"At room temperature, micron-sized sheets of free-standing graphene are in constant motion, even in the presence of an applied bias voltage," the team explains in the abstract to the paper. "We quantify the out-of-plane movement by collecting the displacement current using a nearby small-area metal electrode and present an Ito-Langevin model for the motion coupled to a circuit containing diodes."

In short, the team developed "an energy-harvesting circuit based on graphene could be incorporated into a chip to provide clean, limitless, low-voltage power for small devices or sensors," in the words of lead researchers Paul Thibado — harvesting that movement into usable current.

Previously, the approach had been discounted as impossible: Physicist Richard Feynman notably asserted that there is no way to harness the thermal motion of atoms to produce useful work. By producing a circuit with two diodes acting in opposition to produce usable energy from the graphene device, the team claims to have refuted that.

"We also found that the on-off, switch-like behaviour of the diodes actually amplifies the power delivered, rather than reducing it, as previously thought," Thibado adds. "The rate of change in resistance provided by the diodes adds an extra factor to the power."

There are a few hurdles yet to be jumped before the circuit can be used in anger, however: The team hasn't yet succeeded in storing the energy, which it aims to do by miniaturizing the circuit design for patterning onto a silicon wafer and then storing the output of millions of the circuits working in unison in a capacitor.

The team's work has been published in the journal Physical Review E under closed-access terms; the University of Arkansas has patented the technology, and has already licensed it for commercialization through its venture arm.