May 2000

Molecular Computing

Continued from page 3

By David Rotman

The World Between

While folks like Heath are sanguine, the technology has its share of doubters. The field of molecular electronics "is in love with itself," says Rick Lytel, a computer scientist at Sun Microsystems. Despite his skepticism, however, Lytel is keeping a sharp eye on the field for Sun and is developing specifications to test and evaluate prototype molecular devices. He believes molecular electronics could eventually find uses as memory devices. But Lytel says many of his colleagues in the field have deluded themselves into thinking that they are "only a step away from the marketplace."

Even believers in the prospects of molecular electronics disagree with one another over the role the technology will play in computation and electronics. Take Mark Ratner, a chemist at Northwestern University who is generally regarded as one of the grandfathers of the field. Ratner doubts molecules will ever compete directly with silicon in complex computational tasks. "You want to use molecules for what they do best" and to compensate for where silicon falls short, says Ratner. In particular, he points to their ability to recognize and respond to other molecules. By combining those functions with the newly developed electronic properties, you might make tiny sensors and actuators that detect and react intelligently to biological and chemical clues. It might, says Ratner, make possible implantable biochips incorporating sensors and actuators made out of molecular electronics that sense the needs of the body and respond by discharging an appropriate dose of medication.

For this pioneer of molecular electronics, the true potential of the field could be realized in bringing the world of microelectronics together with the world of biology and molecules. Molecular electronics, suggests Ratner, could be the piece of the puzzle that finally helps to bridge the material gap between biology and computing.

Molecular Sampler Organization Key Researchers Focus Delft University of Technology Cees Dekker Using carbon nanotubes as nanowires and electronic devices; has built a transistor out of a single nanotube Harvard University Charles Lieber Synthesizing arrays of carbon nanotubes that can act as both wires and electronic devices Hewlett-Packard/UCLA R. Stanley Williams, Philip Kuekes (HP); Fraser Stoddart, James Heath (UCLA) Chemically assembling arrays of reconfigurable switches for memory and logic; goal is to build a molecular computer IBM Research Phaedon Avouris Studying the properties of nanotubes; has made a transistor out of a single nanotube Rice University James Tour Developing a self-assembled computer with a highly interconnected network of logic and memory; has synthesized molecules with desirable properties University of Colorado Josef Michl Building a molecular computer; has made suitable molecules and short wires Yale University Mark Reed Collaborating with Rice University to build a molecular computer; has fabricated molecular switches and memory devices