Graphene: Can the Newest Form of Carbon Be Made to Bend, Twist and Roll

Apr 21, 2010 By Kim McDonald
Graphene: Can the Newest Form of Carbon Be Made to Bend, Twist and Roll
Carbon nanoscrolls have open edges and no caps, allowing them to change their shape and diameters. Photo: Michael Fogler

(PhysOrg.com) -- Can graphene -- a newly discovered form of pure carbon that may one day replace the silicon in computers, televisions, mobile phones and other common electronic devices -- be made to bend, twist and roll?

Physicists at UC San Diego and Boston University think so. In a paper published in the journal Physical Review B, the scientists say the propensity of graphene—a single layer of arranged in a — to stick to itself and form carbon “nanoscrolls” could be controlled electrostatically to form a myriad of new devices.

Unlike carbon nanotubes—cylindrical molecules of pure carbon with novel properties that have become the focus of much of the attention of new application in electronics and materials development— nanoscrolls retain open edges and have no caps.

“As a result, nanoscrolls can change their shape and their inner and outer diameters, while nanotubes cannot,” said Michael Fogler, an associate professor of physics at UCSD and the first author of the paper.

Working with Antonio Castro Neto, a physics professor at Boston University, and Francisco Guinea of the Institute of Materials Science in Madrid, the scientists proposed the construction of a device in which the of graphene are used to roll and unroll the nanoscroll.

“The device we envision is a graphene nanoscroll that can be charged by current from a nearby electrode,” said Fogler. “The more charged it becomes, the more the mutual electrostatic repulsion of electrons inside the scroll causes it to unwrap. So, the voltage on the can control the diameter and the number of coils in the scroll.”

“We show in this paper that the electrostatic control of nanoscrolls is very much feasible. The required voltages are in the practical range. Since graphene is so light, the wrapping and unwrapping would occur on a time scale of one-trillionth of a second. So, not only the degree of scrolling can be controlled, these nano-electromechanical devices will also be ultra-fast.”

Fogler said such nanoscrolls could have a wide range of applications, such as actuators whose operation resembles the blinking of one’s eyes, valves in lab-on-a-chip devices and even a form of electronic paper. Previously, other scientists attempted to build scroll “machines” using thin plastic films but they were either too rigid or too frail to work well. In contrast, nanoscrolls made of graphene, which is mechanically stronger than any other material known to man, would be robust, yet remain ultra-light and ultra-flexible. They would also conduct electricity more than a thousand times better than silicon.

Fogler said that the ideas to use electrical properties of graphene to modify its structure, or vice versa, are still quite new, and so the proposed devices may require some time to develop. In the near term, scientists hope that , which is an optically transparent conductor of electricity, could be used to replace current liquid crystal displays that employ thin metal-oxide films based on indium, a rare metal that is becoming increasingly expensive and likely to be in short supply within a decade.

Explore further: Nano filter cleans environmentally hazardous industrial byproducts

More information: An advance copy of the journal article appeared online this week at: link.aps.org/doi/10.1103/PhysRevB.81.161408

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User comments : 4

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danlgarmstrong
4 / 5 (2) Apr 21, 2010
Interesting. I wonder if this might be a good way to store hydrogen. Lots of surface area to hold the hydrogen. Then apply a charge to squeeze it out like toothpaste! No - a charge makes it expand...still - its an idea. Graphene is amazing.
Buyck
Apr 21, 2010
This comment has been removed by a moderator.
StarDust21
2 / 5 (1) Apr 21, 2010
how is that a news?
FastEddy
not rated yet Apr 23, 2010
How is this important (news)? How about a conductor shield of Graphene, like a miniature coaxial cable ... or maybe not so miniature? Or how about a metallic conductor with Graphene cladding or wrapping to improve conductivity of the whole? ... And for further consideration: Is this rolled up Graphene "tubing" stiff or flexible? Strongly stiffened enough to support macro weight (against gravity) in a larger, practical application? Springy like a tuning fork or flexible as a human hair? ...
MikeLisanke
not rated yet May 01, 2010
With a little more complexity, they're making polypeptides with engineered subgroups self-assemble into to similar rolls.

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