Posted on behalf of Shamini Bundell
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Did you ever make paper snowflakes as a kid? The kind where you fold a circle of paper several times, cut shapes out, then unfold it to reveal a beautifully symmetrical pattern? This is kirigami, the ancient Japanese art of paper cutting. Now physicist Melina Blees has applied the same technique to the ‘supermaterial’ graphene — strong sheets of carbon a single atom thick.
Blees, who works in Paul McEuen’s group at Cornell University in Ithaca, New York, has a background in the visual arts and so was used to getting to grips with the potential of a new material. What she didn’t realise was that this experience would help her turn graphene into tiny mechanical components for future nano-machines.
The Cornell team were working on a big sheet of graphene. One of the first things they did was start to physically explore its properties, like a child with a new toy. “We were sort of playing with these large sheets of graphene and it was crumpling and un-crumpling,” recalls Blees. They realised that it had the same kind of stiffness and flexibility as a sheet of paper. It was then that they thought of cutting it.
The team turned to kirigami (from kiru, meaning ‘to cut’, and kami, meaning ‘paper’), in which intricate three-dimensional shapes are formed from folding and cutting a sheet of paper. They picked up a children’s book on the technique and chose some of the simplest shapes.
Melina Blees talks about the kirigami shapes the Cornell team has made from graphene
Melina and her colleagues found themselves “sitting in a high tech lab with scotch tape and paper and scissors”. Their low-tech experimentation led to discoveries with amazing potential. One of the first was a method for turning a single sheet of graphene into a stretchable spring using just a few cuts.
The group played around with different kinds of mechanical structures — pyramids, cantilevers and hinges — just a few tens of micrometres across. These basic components herald a day when physicists might make entire machines on minute scales.
Melina hopes to create tiny weighing scales from graphene springs, for instance, or to design nets that could lie over a living cell and measure electrical signals. Going smaller still, such approaches could one day allow the creation of nanoscale robots.
It’s difficult to imagine how things work at the micrometre scale with attendant differences in forces and properties. Scientists are usually one step removed from microscopic materials such as graphene, and have to use microscopes and robots to see and manipulate them. But Melina found that just poking at a sheet of graphene to see what happened was key to understanding its potential.
Kirigami graphene also shows what scientists can learn from art — and from going back to basics. High-tech experiments are all very well, but there’s a lot to be said for just messing about with materials. Now who wants to make a graphene snowflake?
Read the original Nature paper here. Shamini Bundell is a science communicator and multimedia editor at Nature. She tweets at @SBundell.
For Nature’s full coverage of science in culture, visit www.nature.com/news/booksandarts.