This is the graphene ping list.
Click Private Reply below to join or leave this list.
Interesting: 10 Uses for Graphene.
Posted on 02/21/2022 11:11:46 AM PST by ShadowAce
FAYETTEVILLE, Ark. – A team of University of Arkansas physicists has successfully developed a circuit capable of capturing graphene's thermal motion and converting it into an electrical current.
“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 Paul Thibado, professor of physics and lead researcher in the discovery.
The findings, titled "Fluctuation-induced current from freestanding graphene," and published in the journal Physical Review E, are proof of a theory the physicists developed at the U of A three years ago that freestanding graphene — a single layer of carbon atoms — ripples and buckles in a way that holds promise for energy harvesting.
The idea of harvesting energy from graphene is controversial because it refutes physicist Richard Feynman’s well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado’s team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible.
In the 1950s, physicist Léon Brillouin published a landmark paper refuting the idea that adding a single diode, a one-way electrical gate, to a circuit is the solution to harvesting energy from Brownian motion. Knowing this, Thibado’s group built their circuit with two diodes for converting AC into a direct current (DC). With the diodes in opposition allowing the current to flow both ways, they provide separate paths through the circuit, producing a pulsing DC current that performs work on a load resistor.
Additionally, they discovered that their design increased the amount of power delivered. “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 Thibado. “The rate of change in resistance provided by the diodes adds an extra factor to the power.”
The team used a relatively new field of physics to prove the diodes increased the circuit’s 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 coauthor Pradeep Kumar, associate professor of physics and coauthor.
According to Kumar, the graphene and circuit 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, said Thibado, 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,” Thibado said.
The team 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. In fact, if no current was flowing, the resistor would cool down,” Thibado explained. “What we did was reroute the current in the circuit and transform it into something useful.”
The team’s next objective is 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, they could serve as a low-power battery replacement.
The University of Arkansas holds several patents pending in the U.S. and international markets on the technology and has licensed it for commercial applications through the university’s Technology Ventures division. Researchers Surendra Singh, University Professor of physics; Hugh Churchill, associate professor of physics; and Jeff Dix, assistant professor of engineering, contributed to the work, which was funded by the Chancellor’s Commercialization Fund supported by the Walton Family Charitable Support Foundation.
This strikes me as a step away from your favorite subject.
I should have looked, you’re already here!
Maybe not. Sounds like the premise of The Matrix; they’re all batteries now.
can these devices be scaled up to refrigerator or truck or house size?
Thanks for describing this well. My level of knowledge couldn’t concisely do that.
Everybody seems fixated on the word “limitless”. I get it.
HOWEVER, it seems to me that the far more important aspect is the the fact that, if true, they have refuted the belief that the thermal motion of atoms cannot do work. That’s a huge shift in what may be possible. If I was on that team, I’d be doing back flips.
This is the graphene ping list.
Click Private Reply below to join or leave this list.
Interesting: 10 Uses for Graphene.
BUMP
That’s what I suspect, for instance ambient sound (phonon) energy. ( perhaps from nearby bullhorns announcing preposterous claims of repealing thermodynamics). They say in the blurb graphene mysteriously converts thermal noise to usable frequency vibrations but it more just resonates to sound wave inputs, folks.
“Graphene is a zero-gap semiconductor, because its conduction and valence bands meet at the Dirac points. The Dirac points are six locations in momentum space, on the edge of the Brillouin zone, divided into two non-equivalent sets of three points. The two sets are labeled K and K’. The sets give graphene a valley degeneracy of gv = 2. By contrast, for traditional semiconductors the primary point of interest is generally Γ, where momentum is zero.”
Paging Mr. Galt. Mr. John Galt please pick up the white courtesy phone.....
Ping to John Galt’s motor, stashed at the abandoned ruin of the Twentieth Century Motor Company in Starnesville, Wisconsin.
“Dated” has grown into being the most laughable euphemism around in the last several years.Two guys watching a buxom babe walk by, one turns to the other and says “I want to DATE her SO BAD!”
“Dated” has grown into being the most laughable euphemism around in the last several years.Two guys watching a buxom babe walk by, one turns to the other and says “I want to DATE her SO BAD!”
“Dated” has grown into being the most laughable euphemism around in the last several years.Two guys watching a buxom babe walk by, one turns to the other and says “I want to DATE her SO BAD!”
“Dated” has grown into being the most laughable euphemism around in the last several years.Two guys watching a buxom babe walk by, one turns to the other and says “I want to DATE her SO BAD!”
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.