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The Next Plastic Revolution

Plugged-in polymers—from electronic paper to gene detectors—are on a roll.

You might mistake Alan Heeger for a slimmed-down Jerry Garcia clone—white mane and beard, laid- back attitude, all-black outfit. Ask the UC Santa Barbara physicist to empty his pockets and you won't find guitar picks and a roach clip. But he will produce a handful of transparent vials. Inside each is an ounce of clear liquid infused with invisible flecks of plastic that mimic the molecular structure and behavior of metal. Zap the solution with electricity—or simply expose it to a bright light—and the mixture emits a steady glow.

Neat trick. Heeger and two colleagues won the 2000 Nobel Prize in chemistry for the accomplishment: coaxing conductivity from plastic. (The material in the vials is a luminescent semiconducting polymer.) Now their efforts, and those of a growing number of chemists, physicists, and engineers, are clearing the way for superthin digital screens, polymer computer memory, disposable electronics, and a new generation of smartcards.

Conventional plastic is a lousy conductor. Viewed using an electron microscope, its molecular structure resembles a snarl of spaghetti. But arranging polymer molecules into long, straight rods lets electrons flow freely, approximating the conductivity of traditional materials like silicon or copper. Heeger and his co-Nobelists, for example, discovered that oxidizing the polymer polyacetylene with iodine vapors increased conductivity more than a billionfold.

Their research led to the development of organic light-emitting diodes. Today, OLEDs have begun to replace the bulkier, more expensive LEDs found in small consumer electronics. “The initial products will be two-color screens in cell phones and PDAs,” says Heeger, who cofounded Uniax, now a DuPont subsidiary, to commercialize OLED technology. Full-color displays aren't far behind.

The new semiconducting plastics have even more uses. For example, they're proving perfect for complex integrated circuits that can be sprayed onto anything using modified inkjet technologies—no expensive clean rooms necessary. That has the attention of dozens of fledgling businesses, as well as industry veterans Dow, IBM, Philips, and Xerox, which are pouring millions of dollars into polymer research.

To be sure, plastic circuits aren't as fast or as small as their silicon counterparts, which conduct electricity about 1,000 times faster. Don't expect to see polymer microchips anytime soon. But what plastic electronics lack in speed, they make up in flexibility and low cost. By spraying them onto cheap, standard plastic, for example, or even paper, engineers will be able to construct microthin digital displays that can be folded, twisted, rolled up, or slapped on a billboard or bus shelter for live-action advertising. You could carry your laptop screen in your pocket. Polymer proponents envision printing disposable circuits onto any surface—newspapers, soup cans, wallpaper, work surfaces, even windows.

And the innovation goes on. A company in Britain, Plastic Logic, is pushing polymers into a broader range of products. The two-year-old startup is using a material called Pedot (polyethylenedioxythiophene, if you really want to know) to develop memory chips, disposable electronics, smartcards, and anti-counterfeit devices. Researchers at UC Berkeley have demonstrated a solar-reactive material that can be painted onto almost any surface.

And back at UC Santa Barbara's Institute for Polymers and Organic Solids, Heeger is perfecting polymer biosensors that attach themselves to targeted bits of DNA. The sensors light up in the presence of genetic sequences that predispose patients to, say, Parkinson's disease. Using an ordinary blood sample, genetic testing could be cheap and instantaneous. So don't be surprised to see a live-action ad for it on your soup can.