Gecko-inspired dry printing of nanotube patterns to revolutionize microelectronics

Washington, Jan 26 (ANI): Inspired by how a gecko sticks to the smoothest of surfaces via strong van der Waals force between its millions of hairs, researchers at Rice University have come up with a way to transfer forests of strongly aligned, single-walled carbon nanotubes (SWNTs) from one surface to any other surface in a matter of minutes.

Developed by graduate student Cary Pint, the template used to grow the nanotubes, with its catalyst particles still intact, can be used repeatedly to grow more nanotubes, almost like inking a rubber stamp.

The study also puts forth a way to quickly and easily determine the range of diameters in a batch of nanotubes grown through chemical vapor deposition (CVD).

Common spectroscopic techniques are poor at seeing tubes bigger than two nanometers in diameter - or most of the nanotubes in the CVD "supergrowth" process.

"This is important since all of the properties of the nanotubes - electrical, thermal and mechanical - change with diameter. The best thing is that nearly every university has an FTIR (Fourier transform infrared) spectrometer sitting around that can do these measurements, and that should make the process of synthesis and application development from carbon nanotubes much more precise," he said.

The researchers are also investigating ways to take printed films of SWNTs and make them all conducting or all-semi conducting - a process Hauge refers to as "Fermi-level engineering" for its ability to manipulate electron movement at the nanoscale.

When combined, the techniques represent a huge step toward a nearly limitless number of practical applications that include sensors, highly efficient solar panels and electronic components.

"A big frontier for the field of nanoscience is in finding ways to make what we can do on the nanoscale impact our everyday activities. For the use of carbon nanotubes in devices that can change the way we do things, a straightforward and scalable way of patterning aligned carbon nanotubes over any surface and in any pattern is a major advance," said Robert Hauge, a Rice distinguished faculty fellow in chemistry.

Pint believes industries will take a hard look at the technique, which he said could be scaled up easily, for embedding nanotube circuitry into electronic devices.

His own goal is to develop the process to make a range of highly efficient sensing devices.

He is also investigating doping techniques that will take the guesswork out of growing metallic (conducting) or semiconducting SWNTs.

The study has been published in the online version of the journal ACS Nano. (ANI)