Scientists crumpled a material one atom thick — and discovered a new way to control electricity
Researchers from the USA and the UK discovered that an almost invisible change in the shape of graphene — an extremely thin material — can dramatically affect the way electricity passes through it. In a study published in the journal "Advanced Materials", it was found that wrinkles smaller than a billionth of a meter are capable of changing the electrical properties of the material.
Researchers from the USA and the UK discovered that an almost invisible change in the shape of graphene — an extremely thin material — can dramatically affect the way electricity passes through it. In a study published in the journal "Advanced Materials", it was found that wrinkles smaller than a billionth of a meter are capable of changing the electrical properties of the material. This finding may in the future open the possibility of producing electronic components in which current can be controlled solely by bending and shaping, without the need to change the chemical composition.
Graphene is an extremely thin material made of carbon. To understand how thin it is, one can imagine a surface with a thickness of only one layer of atoms. Despite the tiny dimensions, it is a very strong material capable of conducting electricity well, which is why scientists have been examining for years how it can be used in future technologies.
In the new study, the researchers sought to test what happens when the thin surface is not perfectly straight. They examined tiny natural wrinkles that formed in the graphene, which were less than a billionth of a meter in size, and discovered that the small distortion significantly affects the passage of electricity in the area.
One can imagine the wrinkles as a kind of tiny speed bumps for the electric current. When the graphene bends sharply, the electric charges within it change their position slightly. As a result, a side with one type of charge is created in the wrinkle area, and opposite it a side with an opposite charge — similar to a tiny battery.
"Imagine you are bending a flexible ruler, except the bend is compressed into a space smaller than a billionth of a meter," explained Satwika Ajay Iyengar, who led the research while working at Rice University. "At this scale, the electrons in the graphene move slightly toward one side and create two opposite electrical poles, like the ends of a tiny battery."
The researchers found that the electrical effect created in the wrinkles was particularly strong. The measured polarization reached an intensity up to 10 million times higher than that observed in much larger systems where bending a material creates a similar response. It also turned out that the most important factor is not necessarily the size of the wrinkle, but the degree of its sharpness.
"It turned out that the sharpness of the wrinkle is much more significant than its overall size," said Iyengar. "This means that we may be able to tune the electrical behavior by precisely controlling the curvature at the nanometer scale."
The possible implication is that in the future, what looks like a flaw in the material may actually become a useful tool. If scientists succeed in creating precise wrinkles in the desired locations, they might be able to determine how electricity will pass inside a tiny component using its shape alone. This could be particularly useful in sensors and very thin electronic devices.
Prof. Pulickel Ajayan from Rice University explained: "Our work shows that even a regular wrinkle can become an extraordinary electronic feature when you look at it at the atomic scale." According to him, the fact that the shape of the graphene alone can change its electrical behavior opens the possibility of designing materials using their physical structure, instead of adding other materials to them.
However, this is still basic research. Because of the tiny size of the wrinkles, the researchers relied on computer models alongside measurements to understand the phenomenon. Further studies will need to confirm the results and test whether the effect can be controlled precisely enough to be used in actual technology.
The idea that bending graphene might create an electrical change was proposed nearly 20 years ago, but until now it was difficult to obtain direct evidence for the phenomenon. The new study allows scientists to examine in more detail how a tiny curvature affects electricity in the material.
Graphene attracts much scientific interest due to the unusual combination of extreme thinness, strength, and electrical conductivity. Over the years, possibilities have been tested to use it in sensors, electronics, and filtration systems, among other things. The innovation in the current research is the understanding that the shape itself can also become a tool for controlling the material's properties. Instead of changing its composition, it may be possible in the future to create tiny wrinkles and curves at planned points and thus determine how an electronic component will function.
As Iyengar concluded: "Nature already creates these tiny wrinkles for us. Understanding how they affect electrical behavior gives scientists another tool for designing future technologies using the structure of the material itself."
