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Thibado and colleagues show that micron-sized sheets of freestanding graphene keep moving at room temperature, even while a bias voltage is applied. Using a scanning tunnelling microscope, they measure that out-of-plane motion as a displacement current collected by a nearby small metal electrode. A Langevin model couples the moving membrane to a circuit containing diodes. The system settles into thermal equilibrium, with heat, work and entropy production rates falling quickly to zero, yet the graphene still delivers power equal to what the load resistor dissipates. Their exact power formula resembles Nyquist's noise formula, except that the changing diode resistance strongly boosts the output and the graphene's motion shifts the spectrum to lower frequencies.

Fluctuation-induced current from freestanding graphene