Like paper, graphene twists, folds into nanoscale machines
Graphene, like the paper models, is strong but flexible, and can be stretched or pulled with forces comparable to those exerted by motor proteins. Image Credit: Joe Wilensky/Cornell Chronicle, Cornell University
The art of kirigami involves cutting paper into intricate designs, like snowflakes. Cornell physicists are kirigami artists, too, but their paper is only an atom thick, and could become some of the smallest machines the world has ever known. A research collaboration led by Paul McEuen, the John A. Newman Professor of Physical Science and director of the Kavli Institute at Cornell for Nanoscale Science (KIC), is taking kirigami down to the nanoscale. Their template is graphene, single atom-thick sheets of hexagonally bonded carbon, famous for being ultra thin, ultra strong and a perfect electron conductor. They have demonstrated the application of kirigami on 10-micron sheets of graphene (a human hair is about 70 microns thick), which they can cut, fold, twist and bend, just like paper. Graphene and other thin materials are extremely sticky at that scale, so the researchers used an old trick to make it easier to manipulate: They suspended it in water and added surfactants to make it slippery, like soapy water. They also made gold tab “handles” so they could grab the ends of the graphene shapes. Arthur Barnard, also a Cornell physics graduate student, figured out how to manipulate the graphene this way.