Computer chips are arguably the most complex objects ever built by humans. Manufacturing a Pentium chip involves up to 5,000 steps of painting, etching, and polishing as up to 25 layers of metal and insulator are stacked onto a silicon wafer.
Imagine a yard-wide sheet of plastic coated in thin layers of metal and semiconductor rolling off a spool in a factory. That sheet passes under a printing press like a rolling pin, which imprints millions of transistors, capacitors, diodes, and wires onto it. The sheet then scrolls through an etcher to complete the printing process. The sheet would wind onto another spool as a finished product: perhaps a sheet of solar cells that could be unrolled and cut to size on a roof, or a flexible television display that could unwind like a blind in a living room.
Mr. Maltabes is working on these so-called “roll-to-roll” methods for making flexible, paper-thin computer displays. But he believes that the cheaper manufacturing and more flexible, durable products could fundamentally change the economic equation of what is affordable to do with electronics in general.
“There are devices that we can't even imagine now,” says Maltabes. “You could 'sensor' the world. Think about wrapping the pipes in your house with some kind of material that actually senses the temperature of your pipes. They tell you the pipes are about to freeze and warm them so they don't freeze.”
Or smart bandages that sense inflammation in a wound and release medications. Or lighted wallpaper, purchased by the roll at Home Depot, that changes color and hue with the turn of a knob.
One gadget being created with US military funds is the so-called Dick Tracy wristwatch: This flexible band, strapped on a soldier's wrist, would provide communication, satellite images, and Google Earth-style maps. “You should be able to shoot a bullet through it and have everything work except for the place where there was a hole,” says Maltabes, of the device, under development at Arizona State University's Flexible Display Center.
Roll-to-roll manufacturing could also lower the cost of making batteries. Yi Cui, a nanotechnologist at Stanford University, in California, is printing experimental batteries on paper and cloth using inks that contain carbon nanotubes and lithium-containing dust.
The technology potentially overcomes a major problem: Engineers would like to store electricity produced by solar and wind farms during the day, so it can be used at night – but the cost of today's lithium batteries renders this out of reach.
The “scale of the problem does not match,” says Dr. Cui. “You put together all of the lithium batteries we've made for the last 20 years to power the U.S. electrical grid and you can probably only power it for five to seven minutes.” Cui hopes, though, that printed batteries can be expanded to that massive scale.
Roll-to-roll could propel another green technology – printed solar cells – into widespread use in developing countries, enhancing the decentralized, off-grid economies that are already emerging.
In areas without electricity, small propane or solar-powered generators are already used to recharge cellphones – or sometimes even small LED lights, says Sandeep Tiwari, a nanotechnologist at Cornell University in Ithaca, N.Y., who devotes some of his time to developing world technologies.
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