Nanotech takes defects into account

It's greased lightning, it's Molecularelastic…

Nanotechnology, long a feature of sci-fi novels, came a step closer to reality this week as researchers from Hewlett Packard and the University of California, Los Angeles announced that they have made logic gates the size of a molecule. The research opens the road for the electronics industry, beyond the limits of silicon. With current technology, silicon is expected to be in real trouble in about 10 to 15 years, as the size of the circuits - made by etching silicon wafers with lasers - have been limited by the wavelength of the light. However, the new process being researched in California uses a chemical process to make its tiny components. Each will have defects and be subtly different from every other but in a defect tolerant environment, this need not be a problem. Teramac, a supercomputer assembled from defective parts, has special software that hunts for defects, works out viable communication routes and trains the computer to use only those routes. UCLA researchers think that using the same architecture on a nano scale will mean the molecule sized gates would function properly, despite flaws. "It's an important idea that you can cobble together a working machine out of unreliable components," says Bruce Maggs, a computer scientist at Carnegie Mellon University in Pittsburgh. According to the researcher's report, published in this week's Science, the gates were made from an array of configurable switches. The switches themselves were made of a layer of redox-active rotaxanes sandwiched between metal electrodes. (Yes, we are confused too.) For now, the gate can only be switched once from one state to another, not repeatedly as it would need to in a transistor. But the general response from people in the field has been positive. "The field is still in its infancy," commented Mard Reed, a chemist at Yale University. "But over the last five years we've come from an incredible idea to the point where we might actually be able to do something." And the future is looking rosy according to James Heath, a UCLA chemistry professor who worked on the project. He predicts that eventually the power of 100 workstations could be replicated in a space the size of a grain of salt. ®

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