Nanotubes boost storage

Scientists from IBM Research in Zürich, Osaka Prefecture University in Japan, and the Japanese Nanotechnology Research Institute have advanced the possibilities of using multiwalled carbon nanotubes to make denser, more efficient data storage devices.

Carbon nanotubes are rolled-up sheets of carbon atoms that form naturally in soot, and multiwalled carbon nanotubes are formed from layers of successively smaller tubes. A single nanotube can be smaller than one nanometer in diameter. It takes just 10 hydrogen atoms to span a nanometer.

The researchers previously showed it was possible to use multiwalled carbon nanotube tips rather than silicon to write data onto a polymer film. Binary data is written by heating the polymer to make indentations that represent 1s; blank spaces represent 0s.

The researchers have brought the technology a step forward with a demonstration that shows that the nanotube tips can be used to write more than 250 gigabits -- the capacity of 6.6 DVDs -- per square inch.

They also showed that heat transfers more easily between the nanotubes and the polymer surface than between silicon tips and polymer, making the power efficiency of nanotube tips higher than conventional silicon tips.

It is likely to be at least five years before carbon nanotube tips can be used in practical devices, according to the researchers. The work appeared in the August 11, 2003 issue of Applied Physics Letters.