Israeli scientists use DNA to build circuit

JERUSALEM — Israeli scientists have become the first to "coax" individual biological molecules into forming an electric circuit.

This marriage of biotechnology and electronics will eventually make possible the production of a transistor that is only 1/100,000th the width of a human hair.

The breakthrough was accomplished by Prof. Uri Sivan, Dr. Erez Braun and Dr. Yoav Eichen of the Technion.

"In conventional microelectronics, you start trying to reduce size as much as possible, from the top down. In a biological system, you begin with information in the DNA and build from bottom to top," Sivan explained last week on the eve of the publication of their discovery in Nature magazine.

"No one can manually arrange molecules of this size — which can be viewed only via an atomic force microscope. So we had to use molecules in which all chemical information is coded, allowing self-assembly into structures based on chemical selectivity."

He added that the basic problem the team overcame is that "if you look for a system that builds itself, the molecules are insulated and don't transfer electricity; metals, which do pass electrons, don't self-assemble. We therefore decided to integrate biological and electronic materials to take advantage of both properties."

In a series of experiments, the scientists demonstrated their concept by producing a conducting metal wire connecting two gold electrodes 12 microns apart. The diameter of the wire was 100 nanometers.

"The applications could take 20 years, but they are virtually infinite," explained Sivan. "Using transistors of this size, you could store all knowledge printed in every book in the world inside a cube one-fifth of a millimeter in each direction.

"Our work was basic science, and applications in nanoelectronics are still far off," he said. "But this alternative technology to micro-electronics will allow the production of devices that are 100 to 300 times smaller, with higher complexity, at a lower cost."