Control of the contraction of artificial muscle bundles in the form of graphene

(Duke University) - Duke University engineers are transplanting an array of atomic carbon mesh with polymer resin to create uniform materials with diverse applications, including artificial muscles. .

The above-mentioned grid, known as graphene, is made of pure carbon and appears under an exaggerated copy like a thin steel grid. Graphene is a flat sheet of one atom thick of carbon atoms with sp2 bonds forming a honeycomb-shaped stereotype. Its name is composed of 'graphite' (graphite) and the suffix '-en' (English '-ene' ); in which graphite itself is caused by many graphene sheets.

Because of its optical, electrical and mechanical properties, graphene is used in electronic materials, energy storage, mixed materials and the biological and physiological application industry in clinical medicine (y born).

However, it is very difficult to process graphene in a 'coiled' state , which, depending on the case, may have positive or negative characteristics. Unfortunately, scientists have yet to control the roll and spread of graphene on a large area to take advantage of the resources mentioned above.

Xuanhe Zhao of Duck, an associate professor at Duke's Pratt School, who specializes in engineering, compared the challenge of graphane control to the difference between paper roll and water-repellent paper.

'If you scratch a piece of paper normally, you can easily spread it , ' said Zhao. 'However, graphene is like a absorbent paper towel. It is extremely thin and sticky and hard to spread, once rolled up. We have developed a method to solve this problem and control the roll and spread of large graphene films ".

Duck's engineers attached graphene to a rubber film that was spread many times over its original size. As soon as the rubber film is relaxed comfortably, the part of graphene is separated from the rubber while the other part is attached to the rubber part, creating a form that is both attached and detached to the size of several. billionth of a meter. When the rubber is relaxed, the compressed part of the graphene becomes clumped. As soon as the rubber film is stretched back, the attached graphene will pull the graphene to shrink out.

'In this way, the coiling and spreading of thick atomic graphene with wide area can be controlled by simply loosening a rubber film, even by hand alone , ' Zhao said.

"Our approach opened the door to exploring graphene's unprecedented properties, resources and functions ," Jianfeng Zang, a postdoctoral colleague in Zhao and cugnx's group, was the first author. "For example, we can convert graphene from transparent to opaque by rolling it, and turning it back just by spreading it out."

In addition, Duke's engineers arranged graphene with various polymer films to create a 'soft' material that could act as muscle tissue by shrinking and spreading as required. When using electricity for grapheme, artificial muscle bundles expand the area; when the power is cut, it relaxes. Controlling by different voltages, the degree of shrinkage and loosening is different, giving tension over 100%.

"Artificial muscles help many different industries, from making robots and delivering medicines to reaping and storing ." Zhao said. 'In particular, they promise incredible improvements in the quality of life of millions of disabled people by providing affordable support devices such as prosthetic arms and legs and braille systems for visually impaired. The extended effect of these new artificial bundles can serve as the influence of piezoelectric materials on global society. "

Zhao's research work was funded by the Center for Triangular Materials Science and Engineering Research of the National Science Foundation (NSF), the NSF Material and Surface Engineering program, and the National Institutes of Health. .