Kirigami graphene could pave way for flexible electronics, microscale devices

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Graphene continues to surprise! A team of researchers at Cornell University, US have found a way to utilise Kirigami to make one-atom thick microscale spring and hinges from graphene – a development they say will pave way for microscale devices and even flexible electronics.

The art of kirigami involves cutting paper into intricate designs, like snowflakes. Using the same principles, a team of Cornell physicists led by Paul McEuen, the John A. Newman Professor of Physical Science and director of the Kavli Institute at Cornell for Nanoscale Science (KIC), demonstrated their finding through application of kirigami on 10-micron sheets of graphene, which they can cut, fold, twist and bend, just like paper.

They tested their graphene kirigami designs on laser-cut paper and found that the graphene soft spring behaved similarly to the paper model.

Using one sheet of graphene they made a soft spring, which works just like a very flexible transistor. The forces needed to bend such a spring would be comparable to forces a motor protein might exert, McEuen said. Entering the realm of biological forces, the experiments open up a new playground of ideas for, say, flexible, nanoscale devices that could be placed around human cells or in the brain for sensing, McEuen said.

The researchers also demonstrated how well graphene bends in a simple hinge design, quantifying the forces needed. Opening and closing the hinge 10,000 times, they found that it remains perfectly intact and elastic – a potentially useful quality for foldable machines and devices at that scale.

Building on the principles from the paper, a related research team at Cornell has just received Department of Defense funding to continue developing technologies around flexible materials like graphene, using some of the kirigami principles demonstrated.

The study’s first author, Melina Blees, a former physics graduate student and now a postdoctoral researcher at the University of Chicago added that over the course of the project, she was able to get an intuitive grasp of graphene’s properties – rare for nanoscale scientists.

“It’s one thing to read about how strong graphene is; it’s another thing entirely to crumple it up and watch it recover, or to stretch a spring dramatically without tearing the materials,” she said. “It’s not every day that you get to develop a feel for a nanoscale material, the way an artist would.”

The work, which also included David Muller, professor of applied and engineering physics and co-director of KIC, was supported by the Cornell Center for Materials Research, which is funded by the National Science Foundation; the Office of Naval Research; and the Kavli Institute at Cornell for Nanoscale Science.