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Featured ProjectEngineering professor researches ways
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Professor Loo wants to conduct research that’s relevant and has an impact on the world. |
Run electricity through the printed plastic sheet and you get electronic devices that are flexible, cheap and clean to manufacture.
How about cheap, disposable and flexible medical indicators? Or wallpaper that changes pattern and color at the flick of a switch? Or a map that lights the route from where you are to your destination?
“We’re thinking of light-weight disposable electronics that are low-end applications,” said Loo, an assistant professor of chemical engineering at The University of Texas at Austin.
Loo and students in her budding laboratory at The University of Texas at Austin are working in plastic electronics, a relatively new but growing area of research.
Plastic electronics won’t replace silicon-based processors for applications that require power or speed any time soon.
“With Pentium chips we’re talking about hundreds of megahertz these days and with organics we’re talking about kilohertz,” Loo said. That’s a speed advantage of 100,000 to one for silicon.
But plastic electronics have advantages that make them ideal for the applications Loo and others envision.
Plastics can be made as big as you want them to be.
“So that’s why the wallpaper analogy comes in,” she said. “And it’s lightweight, so you can just coat it on the wall. It’s lightweight so the hiker can take it with him in his backpack.”
It doesn’t use the solvents needed in making silicon chips and the process promises to be much less expensive than the big-ticket machines used for computer chips.
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Professor Loo’s lab collaborates with DuPont Photomasks, based in Round Rock, Xerox Research Canada and DuPont, the chemical company based in Delaware. |
| Photo: Charlie Fonville |
“Nowadays with silicon chips, you need a really nice clean room and you need very expensive high-vacuum apparatus to build your chips,” said Loo, who learned about making chips at Bell Labs. “So here we envision not needing a clean room.”
Loo established herself in the field even before she came to Texas two years ago.
As a post-doctorate researcher at Bell Labs in New Jersey, Loo developed the nanotransfer printing process for putting electric circuits on plastic.
That earned her a spot on MIT’s Technology Review’s 2004 list of 100 young innovators. UT integrative biologist Dr. Lauren Ancel Meyers also was named to the list for her work in using mathematical models to track the spread of infectious diseases.
The nTP process works like offset printing, with a rubber stamp imprinting designs on a piece of plastic. In this case, the designs are on a nanometer scale.
Loo set the rubber stamp on her desk and explained the printing process.
“The nice thing about this is that when you bring it into contact it goes sluuurrrrp,” she said, mimicking the sound the plastic makes as she peels it from the desk.
The stamp wets the surface of the desk, making atomic contact.
“We’re using that interface to do chemical reactions,” she said. “That’s how we can print.”
The stamps have the raised and recessed designs of a specific level of a circuit.
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The flexibility of plastic makes plastic electronics suitable for applications that are unsuitable for silicon-based electronics. The outset shows the detail of a circuit. |
“We flip it around and print with it,” she said. “And because it’s got this unique property, it’s rubbery and it’s sticky, it prints really nicely.”
In mass production, the printing process would work like the process in printing high-gloss magazine covers where the stamps are wrapped around drums.
“What they do is have a rubber stamp that’s wrapped around a drum and they print high-gloss magazine covers by feeding the magazine through and printing it with these drums,” Loo said, “so if we can wrap these rubber stamps around these drums and print out the individual circuit levels it would be really, really, really cheap.”
In the lab, Loo’s team makes stamps, prints the circuit levels, makes devices and then tests them. Her team then characterizes the materials in the circuits using X-ray scattering and microscopy and they try to correlate materials’ structures with device properties and performance.
So far, much of the work in plastic electronics has involved finding polymer combinations that work and worrying about why they work later.
Loo, however, is working on the why. She and her lab are developing design guidelines that will help steer researchers to the right combination of materials for the right devices.
“There’s no good way, no uniform way of producing devices that are reliable and reproducible as of now,” she said. “So what we’re proposing to do is start from the fundamentals, understand the chemistry, understand the physics, understand why these materials make the structures they do and how the structures affect the device performance.
“Then maybe someday, five, 10, 15, 20 years down the line, we can say ‘Oh, you want to build a device so big and you want to expose it to water. In that case, we can’t use Material A, we have to use Material B. And this is how we have to process Material B.’”
Soon, university scientists will have a place to process such materials, thanks to Loo and Dr. Paul Barbara, a professor of chemistry and director of the university’s Center for Nano- and Molecular Science and Technology.
They obtained an $800,000 grant from the W.M. Keck Foundation to create a central lab on campus for building organic devices.
“There are a couple of us on campus who are really keen on this field and think this is really going to go somewhere,” she said. “So we got money and we’re going to build a central clean room facility. Everybody can come use it.”
Loo has established ties with several companies interested in plastic electronics. The chief technology officer of DuPont Photomasks, based in Round Rock, Texas, attends lab meetings. The company also provides photomasks for use in the lab.
“He can provide insights, downstream insights,” she said. “He provides my students with another perspective that I can never provide.”
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The lab also collaborates with Xerox Research Canada and characterizes materials for the company and DuPont, the chemical company based in Delaware.
Loo grew up in Malaysia and came to the United States to attend the University of Pennsylvania. She went to Princeton University for graduate school and then to Bell Labs.
“I think I’ve always wanted to be a scientist,” she said. “My dad worked for Shell Oil and he’d bring back these refinery charts and I was always inspired by that.”
While she’s a member of the Chemical Engineering Department, Loo said, “I think I’m a material scientist at heart. I like to figure out why certain materials, given their properties, can do certain things.”
Plastics offer much to investigate, she said.
“There are so many different kinds of plastics that have different properties that you can use for almost anything. You have polymers that go into making your clothes. You have Kevlar, which is a high-strength engineering plastic. Why is it so strong? We have milk jugs, which is polyethylene. Why is it opaque? Why isn’t it clear? So these are the kinds of questions I’ve liked to ask.”
And Loo likes to get answers, answers that can lead to a product or application—a realization that struck her in graduate school.
“I wanted to know how what I was doing would have an impact on the world,” she said. “And I wanted to be able to make that connection. To me that’s important. What is your impact, why is the work you’re doing significant? Being able to correlate what you do with an application, no matter how futuristic it is, gives you some sort of relevance.”
Tim
Green
Photos of Dr. Loo: College of Engineering
Dr. Lynn Loo
Department of Chemical Engineering
College of Engineering
Center for Nano- and Molecular Science and Technology
Chemical engineer and biologist make list of world’s top young innovators - 20 September 2004
National Science Foundation grants six engineers CAREER awards totaling more than $2.4 million - 24 May 2004
Chemical Engineering professor receives grant to support microelectronics research - 2 February 2004
