Silicon chips have made everything electronic smaller, faster, and cheaper.

As this ScienCentral News video reports, scientists are working hard to make circuits so small, we won't see them at all.

A Nanotube Boutique

Carbon nanotubes, which consist of graphite sheets in extremely tiny tubular shapes, now symbolize the huge potential of nanotechnology to change materials, manufacturing, medicine, and electronics. But progress in assembling them into anything useful has been slow. One nanotechnologist decided to try building nanotubes from other molecules that are easier to control.

In 1991, Dr. Sumio Iijima, a physicist and materials scientist at NEC Corporation in Japan, discovered carbon nanotubes, a miniscule new form of graphite, the material in pencils. Researchers immediately plunged into looking for ways to harness carbon nanotubes’ impressive strength, flexibility, and potential as electrical conductors. But the surfaces of carbon nanotubes proved to be very slippery. Dr. Pulickel Ajayan is a leading carbon nanotubes researcher at Rensselaer Polytechnic Institute. He began his career working with Dr. Iijima. According to Dr. Ajayan, “When things are small, things are different. A lot of studies have been done, but we are certainly not at the end of the tunnel. We have a long way to go before we can put carbon nanotubes together in the way we want.”

At Purdue University, Dr. Hicham Fenniri, who trained as a biochemist and organic chemist, decided to try making nanotubes out of something easier to control than the slippery form of graphite in carbon nanotubes. In order to accomplish his goal in nanotechnology, Fenniri, like many researchers, had to acquaint himself with another branch of science. He looked for answers in synthetic organic chemistry, which attempts to mimic the way living things build useful structures. Subsequently, inspired by nature’s approach to assembling molecules and armed with the power of synthetic chemistry, he has been able to design molecules which link together in groups of six to form ring-like structures he calls rosettes. The rosettes then form synthetic nanotubes.

On the outside of each synthetic nanotube, Fenniri can add electronic anchors which serve as links for other molecules with the properties he wants each tube to have: “The anchors can be used like a dock in a marina. You can attach a boat, with whatever cargo you like.” Most recently, Fenniri has been able to design nanotubes that can turn right or left. “Most molecules in the natural world are organized in either a right-handed or left-handed direction, and that determines their properties,” Fenniri explains. “If you change the direction, you change the molecules’ properties. For example, sugar loses its sweetness if its handedness is changed.”

Fenniri’s “designer” nanotubes could be used to assemble nano-circuits that could eventually be used in molecular electronics and photonics. Next, he plans to experiment with two methods of using his synthetic nanotubes to assemble circuitry on chips, where they could shuttle electrons through a circuit.