Researchers from the University of Arkansas created a circuit capable of capturing graphene’s thermal motion and convert it into an electrical current. The energy harvesting circuit was incorporated into a chip to provide clean, limitless and low voltage power for small devices and sensors.
The new research proves a theory that free-standing graphene ripples and buckles in such a way that would be useful for clean energy harvesting. This was controversial because past research from the University of Arkansas stated that the thermal motion of atoms cannot do the work needed for energy harvesting.
Paul Thibado, professor of physics, holds prototype energy-harvesting chips. Source: Russell Cothren, University of Arkansas
Researchers found that the room temperature thermal motion of graphene induced alternating current (AC) in a circuit. They build a circuit with two diodes to convert AC into a direct current (DC). With the diodes in opposition, the current can flow both ways and provide separate paths through the current. This produces a pulsing DC current that performs work on a load resistor. The new design increased the amount of power delivered.
To prove the circuit’s increased power, the team used a newer field of physics called stochastic thermodynamics. The graphene and circuit share a symbiotic relationship, so heat does not flow between the graphene and circuit. This is important because a temperature difference would contradict the second law of thermodynamics. The slow-motion of graphene induces a current in the circuit at low frequencies. This is significant because electronics function more efficiently at low frequencies.
The team’s next step is to determine if the DC current can be stored in a capacitor for later use.
A paper on this research was published in Physical Review E.
