- A graphene - based power harvesting circuit can be integrated into a chip to provide clean, limitless, low-voltage power for small components and sensors.
- The research is at odds with existing theories.
- At room temperature, the thermal motion of graphene actually causes an alternating current.
A new project from the University of Arkansas, led by Professor Paul Thibado, successfully developed a circuit that can capture the thermal motion of graphene and turn it into an electrical current. To prove their theory, the team of scientists had to use a new field of physics.
“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,” said Prof. Thibado, professor of physics and lead researcher in the discovery. In proving the power increase, they relied on the nascent field of stochastic thermodynamics and extended the famous Nyquist theorem.
The research is at odds with existing theories. For example, it directly contradicts the work of the famous physicist, Richard Feynman, who suggested that the thermal motion of atoms, known as Brownian motion, cannot be worked with.
However, Thibado’s team discovered something that was previously thought impossible: at room temperature, the thermal motion of graphene actually causes an alternating current. This was made possible by a circuit with two diodes instead of one for converting alternating current to direct current. The diodes were placed opposite each other.
“We also found that the on-off, switch-like behavior of the diodes actually amplifies the power delivered, rather than reducing it, as previously thought,” said Prof. Thibado. “The rate of change in resistance provided by the diodes adds an extra factor to the power.”
“In proving this power enhancement, we drew from the emergent field of stochastic thermodynamics and extended the nearly century-old, celebrated theory of Nyquist,” said co-author Pradeep Kumar, associate professor of physics.
The counting theorem is a fundamental statement in the field of signal processing based on numerical methods that connects continuous and discrete signals. This is Kotelnikov’s Theorem.
Continuous processes, functions, or signals are called analog (from the word analog – something similar, similar to something, i.e. a function as a model is analogous to some physical process).
An analog signal, even at a finite time interval, implies a set of an infinite number of values. However, the recording device usually record a finite number of values, so we obtain discrete-time signals (discrete, from lat. discretus means separate, consisting of separate parts).
The team also found that the relatively slow movement of graphene induces current in the circuit at low frequencies, which is important from a technological point of view, since electronics work 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. In fact, if no current was flowing, the resistor would cool down,” Prof. Thibado explained. “What we did was reroute the current in the circuit and transform it into something useful.”
This is a very exciting finding and basically leads to the new field in physics.