It's one thing to design nanoscale electronic devices ---- tiny devices with components measured in nanometers, or billionths of a meter. It's quite another thing to build them.

That's why chemists at Carnegie Mellon University and Washington University in St. Louis have developed a way to build components that assemble themselves.

Using innovative polymer chemistry, the researchers have developed a method of producing "nanostructured carbons" ---- tiny balls, cones and cylinders ---- through self-assembly. These electrically conductive carbon pieces might then be used to produce a number of devices, such as solar panels, tiny sensors, or miniaturized TV tubes that could be linked together to become flat panel screen displays.

Chuanbing Tang, a Carnegie Mellon graduate student, presented the group's findings yesterday at the American Chemical Society meeting in Anaheim, Calif.

"We now have a way to produce a new class of materials," said Tomasz Kowalewski, the Carnegie Mellon chemist who headed the research effort. By relying on self-assembly, the process is relatively cheap and should be scalable to commercial production, he said.

Tiny carbon tubes called nanotubes also have attractive electronic properties that could be used in nanoscale electronics, Kowalewski said, but it is difficult to produce them in large quantities.

At the heart of the process is a block copolymer ---- a sort of two-headed polymer, which has a water-hating compound, polyacrylonitrile, or PAN, on one end and a water-loving compound, polyacrylic acid, on the other. In a water solution, these polymers tend to form into balls, with the water-loving polyacrylic acid on the outside and the water-hating PAN on the inside.

Different shapes are possible by changing the proportion of each polymer in the block copolymer.

Once these shapes form through self-assembly, a shell-crosslinking technique developed by Karen Wooley of Washington University is used to stabilize them. The nanoclusters are then treated at high temperatures to decompose the outer polyacrylic shell, leaving the inner core of PAN.

The process produces lots of uniform nanoclusters that can then be used to build a variety of devices, Kowalewski said.