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Ink-Jet Printing Facility Set to Crank Out Flexible Electronics

New plant for mass-producing custom light sensors may be the tip of the iceberg
flexible electronics



© NANOIDENT TECHNOLOGIES AG
An Austrian company announced this week that it has opened the first manufacturing plant for printing cheap, disposable light sensors onto custom surfaces such as glass and flexible plastic.

So-called flexible electronics technology is most often associated with slim computer displays that bend like plastic. Nanoident Technologies, based in Linz, aims to produce sensors for applications such as rapid medical testing and fingerprint analysis. But makers of flexible displays and other emerging technologies are gearing up to begin production later this year, meaning that a number of new devices may soon come to market.

To manufacture microprocessors like the ones in home computers and cell phones, a robot repeatedly adds layers of material to a rigid wafer of silicon and then etches away parts of the layers to leave a pattern of circuitry. Industry has honed the technique for decades, but it still relies on those hard wafers, which cannot be used to make pliable computer displays, for example.

In Nanoident's new facility, an industrial-size ink-jet machine prints circuits on top of one of several rigid or flexible materials, including paper. Just as a home ink-jet printer draws letters using ink, Nanoident's printer drizzles liquid polymer or a solution of nanoscale particles in a chosen pattern. The liquid dries and the process repeats, resulting in a sandwich consisting of up to four materials.

Each layer is 20 to 200 nanometers thick and reacts to electricity in its own way; a semiconductor mimicking silicon might be stacked between two transparent conductor layers. The sandwiches can be sculpted into numerous basic devices such as transistors, light detectors and light emitters, says Wasiq Bokhari, CEO of Bioident Technologies in Menlo Park, Calif., a U.S. subsidiary of Nanoident.

"It is flexible electronics," Bokhari says. "Most of the substrates we print on are flexible substrates."

He says Bioident will use the facility to print light sensors directly onto products for rapid medical diagnosis, water testing and chemical and biological weapons monitoring. That way, he says, a plastic slip with a drop of blood on it for diagnosis would not have to go into a separate machine to read out, say, the blood type or blood sugar concentration.

Bokhari says that once a printed device is designed, "within a few days we can have that in mass production. This is almost unthinkable in terms of traditional semiconductors." The new facility should be able to produce millions of devices a year, he says, with shapes as small as a micrometer in size—10 times larger than circuits in silicon microchips.

Printable electronics has been around for a while but in a crude form, equivalent to pouring liquid over a stencil, or mask, says Jim Walker, a semiconductor manufacturing analyst at Gartner Dataquest. "We're just starting with simple circuitry and low numbers of transistors, but the ability to print transistors is a breakthrough in itself," he says. "Ink-jet printing is by far a faster, more customized process than the standard semiconductor manufacturing process."

The Nanoident facility is one of the first of a wave of printed electronics factories, says Craig Cruickshank, founder and chief analyst for cintelliq, Ltd., based in Cambridge, England.

Flexible display–makers Polymer Vision (Eindhoven, Netherlands) and Plastic Logic (Cambridge) should begin production later this year, he says, as well as PolyIC, a German firm working on printed radio bar codes for product tracking.

"What we're seeing is a completely new tool set … to enable the high-speed printing of functional devices," Cruickshank says. "People are now prepared to invest in it."

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