A team of researchers from the University of Arkansas has successfully developed a circuit capable of capturing the thermal motion of graphene and converting it into electric current. Physicists say a graphene-based energy harvesting circuit could be incorporated into a chip to provide clean, unlimited, low-voltage power for small devices and sensors.
Breakthrough is an offshoot of research conducted three years ago at the University of Arkansas that found that independent graphene, which is a single layer of carbon atoms, ripples, and buckles in a way that holds the potential to collect power. The idea was controversial because it refutes a well-known claim by physicist Richard Feynman about the thermal motion of atoms, known as Brownian motion, cannot work.
However, the University researchers found that at room temperature the thermal movement of graphene induces an alternating current in a circuit. Previously it was thought that the result was impossible. The researchers also found that their design increases the amount of power delivered. The researchers say they have found that the on and off behavior of the diodes amplifies the power delivered rather than reducing it as previously believed.
Project scientists were able to use a relatively new field of physics to demonstrate that diodes increase circuit power. That emerging field is called stochastic thermodynamics. The researchers say that graphene and the circuit share a symbiotic relationship. While the thermal environment does work on the load resistor, the graphene and the circuit are the same temperature and no heat flows between the two. This is an important finding because a temperature difference between the two would contradict the second law of thermodynamics.
Other findings included that the relatively slow motion of graphene induces a current in the circuit at low frequencies, which is important from a technological standpoint. This is important because the electronics work most efficiently at the lower frequencies. The next goal is to determine if DC current can be stored in a capacitor for later use. Miniaturization is also planned.