The graphene and circuit, says Kumar, share a symbiotic relationship. Though the thermal environment is performing work on the load resistor, the graphene and circuit are at the same temperature and heat does not flow between the two.
That's an important distinction, say the researchers, because a temperature difference between the graphene and circuit, in a circuit producing power, would contradict the second law of thermodynamics.
"This means that the second law of thermodynamics is not violated, nor is there any need to argue that ' Maxwell’s Demon ' is separating hot and cold electrons," says Thibado.
The researchers also discovered that the relatively slow motion of graphene induces current in the circuit at low frequencies, which is important from a technological perspective because electronics function more efficiently at lower frequencies.
"People may think that current flowing in a resistor causes it to heat up, but the Brownian current does not," says Thibado. "In fact, if no current was flowing, the resistor would cool down. What we did was reroute the current in the circuit and transform it into something useful."
The researchers next plan to determine if the DC current can be stored in a capacitor for later use - a goal that requires miniaturizing the circuit and patterning it on a silicon wafer, or chip. If millions of these tiny circuits could be built on a 1-millimeter by 1-millimeter chip, say the researchers, they could serve as a low-power battery replacement.
For more, see " Fluctuation-induced current from freestanding graphene ."
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