Donghua University/Science Advances
View Caption + #1: A sheet of graphene is thin, just a single atom thick.
Top 10 Uses for the World's Strongest Material
Laguna Design/Science Photo Library/Corbis
View Caption +
Graphene repels water and when mixed with polymer works as a rust-proofing coating.
Bill Stormont/Corbis
View Caption +
Graphene transmits the heat energy from an electrical current to make sound.
University of Texas / Ji Won Suk
View Caption +
Computer chips with graphene supercapacitors could make batteries obsolete.
AB Still Ltd/Science Photo Library/Corbis
View Caption +
Microscopic bits of graphene oxide bind to radioactive contaminants and could make cleaning up nuclear waste safe and cheap.
Karen Kasmauski/Science Faction/Corbis
View Caption +
The first integrated circuit made of graphene was made by researchers at IBM.
IBM
View Caption +
A layer of graphene affixed to a polymer crumples and straightens when a current is run through it.
Laguna Design/Science Photo Library/Corbis
View Caption +
Graphene foam can pick up small concentrations explosive compounds.
Nikhil Koratkar
View Caption +
Graphene turned into a foam filter can be used to sequence DNA.
Moon Kim/UT Dallas
View Caption +
A composite fiber made from graphene and carbon nanotubes is stronger than the Kevlar used in conventional bulletproof vests.
Tim Graham/Sygma/Corbis
View Caption +
A layer of graphene dotted with lead sulfide creates an ultra-sensitive and flexible photodector for night vision.
John Moore/Getty Images
Related Links
Self-folding materials have become a major topic of research in recent years, with particular focus on so-called active polymers, materials that convert other forms of energy into mechanical work. But studies to date have often relied on electrical circuitry, unusual environmental conditions or complicated combinations of materials, which tend to be fragile.
By making their devices entirely out of graphene — a one-atom-thick sheet of carbon that is both incredibly strong and very stretchy — Mu and his colleagues created a device that was still 90 percent effective, even after being folded 500 times. The material also has an energy-conversion rate of 1.8 percent, which is considerably better than the 1 percent or lower achieved by other active polymers, Mu said.
Graphene is the most promising new material out there, likely to revolutionize the way we do or build almost anything. It's pure carbon, and totally amazing. Trace shows us all the different ways this material could change life on Earth.
In addition to having the potential to inspire self-folding devices, the researchers said graphene paper could eventually be used to create artificial muscles. The stress generated by one of the paper devices was nearly two orders of magnitude higher than that of mammalian skeletal muscles, the researchers said.
"Compared with other kinds of self-folding materials, the all-graphene-based structure is simpler, its response behavior is faster and the output is more efficient," Mu said. "More importantly, its origami and walking behavior is remotely controlled."
Pure graphene can be costly and time-consuming to create, though, so the researchers used graphene oxide (GO) to create their paper. This material, Mu said, costs as little 1 Yuan (or 16 cents in U.S. dollars) per gram.
The researchers used GO nanosheets as building blocks to construct larger sheets before carrying out what's known as a reduction reaction to remove oxygen atoms from the GO. This converts the material into reduced GO (rGO), which does not have such impressive properties as pristine graphene, but still shares many of the same characteristics.
Crucially, though, the scientists treated areas of the GO paper with polydopamine (PDA) before carrying out the reduction reaction, which prevented these sections of GO from being reduced. Unlike the rest of the paper, these specially treated areas readily absorb water vapor, giving them the ability to bend.
The team's results were described in a paper published Nov. 6 in the journal Science Advances, but Mu said there is still a ways to go before any practical applications of the paper can be realized.
"We believe there is still room for improvement in the energy-conversion efficiency," he said. "Secondly, we think that as the device scales down in size, especially to nanoscale, its properties and origami performance would change significantly. Therefore we are also interested in developing a nano-size all-graphene origami device."
Get more from Live Science
Original article on Live Science . Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.