Scientists develop 'world's thinnest balloon'

Washington, September 23 : Scientists have created a balloon-like membrane that is just one atom thick, which can be effectively be called as the 'world's thinnest balloon'.

According to a report in the Chronicle Online, the membrane, made using a lump of graphite, a piece of Scotch tape and a silicon wafer, is ultra-strong, leak-proof and impermeable to even nimble helium atoms.

The research, by Scott Bunch, 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.

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 have used graphene in the multi-layer membrane of the world's thinnest balloon, which could be used in various applications, including filters and sensors.

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.

With a tapping atomic force microscope, which measures the amount of deflecting force a tiny cantilever experiences as it scans nanometers over the membrane's surface, the researchers watched the graphene as it bulged in or out in response to pressure changes up to several atmospheres without breaking.

They also turned the membrane into a tiny drum, measuring its oscillation frequency at different pressures.

They found that helium, the second-smallest element (and the smallest testable gas, since hydrogen atoms pair up as a gas), stays trapped behind a wall of graphene - again, even under several atmospheres of pressure.

Such a membrane could have all kinds of uses.

"This could serve as sort of an artificial analog of an ion channel in biology," said McEuen, or as a way to measure the properties of an atom by observing its effect on the membrane.

"You're tying a macroscopic system to the properties of a single atom, and that gives opportunities for all kinds of single atom sensors," he added.

ANI