Nanotubes move molten metal

One challenge in making machines at the scale of molecules is figuring out how to place such tiny amounts of material exactly where you want them.

Researchers from the University of California at Berkeley have found a way to move globules of molten metal that are as small as 30 nanometers in diameter. A nanometer is one millionth of a millimeter, or the span of 10 hydrogen atoms.

The method involves condensing a globule of metal onto one end of a carbon nanotube, then using a voltage to drag the metal globule along the outside of the tube from one end to the other. Reversing the voltage reverses the metal globule's path.

Researchers can move individual atoms with the scanning probe tips of microscopes, but that method is too tedious for practical manufacturing. The University of California method allows small numbers of atoms to be moved around easily enough for practical nanoassembly, according to the researchers.

The method could also be used as a minuscule soldering iron, and works with indium, gold, platinum, and tin.

The method could be used in commercial applications within five years, according to the researchers. The work appeared in the April 29, 2004 issue of Nature.