Using a lump of graphite, a piece of Scotch tape and a silicon wafer, Cornell researchers have created a balloonlike membrane that is just one atom thick -- but strong enough to contain gases under several atmospheres of pressure without popping.
And unlike your average party balloon -- or even a thick, sturdy glass container -- the membrane is ultra-strong, leak-proof and impermeable to even nimble helium atoms.
The research, by former Cornell graduate student Scott Bunch (now an assistant professor at the University of Colorado), Cornell professor of physics Paul McEuen and Cornell colleagues, could lead to a variety of new technologies -- from novel ways to image biological materials in solution to techniques for studying the movement of atoms or ions through microscopic holes.
The work was conducted at the National Science Foundation-supported Cornell Center for Materials Research and published in a recent issue of the journal Nano Letters.
Graphene, a form of carbon atoms in a plane one atom thick, is the strongest material in the world, with tight covalent bonds in two dimensions that hold it together even as the thinnest possible membrane. It's also a semimetal, meaning it conducts electricity but changes conductivity with changes in its electrostatic environment.
Scientists discovered several years ago that isolating graphene sheets is as simple as sticking Scotch tape to pure graphite, then peeling it back and re-sticking it to a silicone dioxide wafer. Peeled back from the wafer, the tape leaves a residue of graphite anywhere from one to a dozen layers thick -- and from there researchers can easily identify areas of single-layer-thick graphene.
To test the material's elasticity, the Cornell team deposited graphene on a wafer etched with holes, trapping gas inside graphene-sealed microchambers. They then created a pressure differential between the gas inside and outside the microchamber.
|Contact: Blaine Friedlander|
Cornell University Communications