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Nanotube Growth Direction Controlled
A US research team has developed a technique to control the growth of nanotubes in different directions at the same time, even standing up from the substrate.

The team reckons this level of control has been achieved for the first time, and could pave the way to building on-chip networks using molecular self-assembly.

The scientists from Rensselaer Polytechnic Institute and Motorola Physical Science Research Laboratories based their method on a selective growth process that allows nanotubes to grow perpendicular to the silica-coated substrate.

By chiselling the silica into predetermined shapes, the researchers could control the growth and direction of the nanotubes.

The team used gas-phase delivery for the metal catalyst, to make the growth process more flexible and more easily scalable than techniques used up to now for growing nanotubes.

The team believes this process for controlled nanotube growth could, in principle, be commercialised in a matter of months.

Ganapathiraman Ramanath, assistant professor of material science at Rensselaer, said: "The impact of our work is well beyond nanotubes. This is the first step toward making complex networks comprising molecular units.

"By manipulating the topography of the silica blocks, and utilising the selective and directional growth process, we have been able to force nanotubes to grow in predetermined, multiple directions with a very fine degree of control. No-one else has done this."

The team believes that its fabrication method can be scaled up to large areas and is compatible with standard chip-making processes.

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