Geckos Used as Inspiration in Nanotube Innovation

Among all the wonders of nature, geckos really stand out for their amazing ability to stick to virtually any surface, regardless of how smooth it is. This is only possible because the animals have millions of microscopic hairs on their feet, which are able to interact with any surface via electrical attractions called van der Waals forces. Now, experts at the Rice University have managed to use the data they had on geckos to produce a new method of transferring patterns of strongly-aligned, single-walled carbon nanotubes (SWNT), from their growth substrate to any another surface.

The achievement is tremendously important because it allows for the same substrate to be used for SWNT growth over and over again, rather than researchers having to change it after every batch of the nanostructures is produced. In a research paper they published in the latest online issue of the respected scientific journal ACS Nano, the Rice experts also detail a new mechanism they created, of determining the range of diameters that SWNT in a certain batch fall within. This technique only works for nanotubes grown via chemical vapor deposition (CVD). The work was conducted by Rice graduate student Cary Pint.

“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,” Pint explains. Regular spectroscopic techniques exhibit poor performances in observing nanotubes with a diameter smaller than 2 nanometers, which basically excludes the vast majority of SWNT produced through the CVD “supergrowth” process.

“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,” says Rice distinguished faculty fellow in chemistry, Robert Hauge. Researchers at the Vanderbilt University and the US Department of Energy's (DOE) Los Alamos National Laboratory also participated in the investigation, which was supported by the Rice-based Lockheed Martin LANCER program.