Nanotechnology has arrived. No longer do we just have to imagine the benefits. Advertisers tout them in cosmetics, clothing, batteries, dental adhesives, paint and golf clubs. In 2004, nanotech consultant Lux Research, Inc., estimated the worldwide sale of products containing nanomaterials at $158 billion. And new products are on the horizon: medicines, sensors, filters and more efficient solar collectors.
If you take a historical view, we’ve been driving to work on nanotechnology for the past century. About one-quarter of an automobile tire consists of nanosize-carbon black particles. Without them, our treads would lack strength and wear resistance.
“Nano” refers not just to small but to a specific kind of smallness. One nanometer is one-billionth of a meter, the width of a human hair sliced lengthwise into 100,000 strands. It takes 10 carbon atoms to span one nanometer. Lined up side by side, 152 million carbon atoms are as wide as a penny.
In 1959, Caltech physicist Richard Feynman issued a call to arms for research at this scale. He explained to a conference of his colleagues how all 24 volumes of the Encyclopaedia Britannica could fit on the head of a pin. Not only is there enough room among the atoms to encode that much information, he argued, “there is plenty of room,” enough for all the world’s books to be copied onto a mote of dust.
Among Feynman’s nanotech dreams were room-sized computers shrunk to the size of a briefcase (check that one off), ingestible surgical devices that could repair a damaged heart and factories that make flawless products, atom by atom.
Today, OSU researchers in engineering, chemistry, physics and wood science are among those putting Feynman’s ideas into practice. Through the Oregon Nanoscience and Microtechnologies Institute (ONAMI), they are working with colleagues at the University of Oregon, Portland State University, the Pacific Northwest National Laboratory and the private sector (HP, FEI, Intel, IBM and others) on projects designed to address manufacturing and safety issues as well as to develop new materials and products. Funding support comes from the State of Oregon and the federal government’s National Nanotechnology Initiative.
The Joke Among Chemists
Among scientists, this investment is both a welcome source of support and validation of existing ideas. “The joke among the chemists is, ‘have you heard about nanotechnology? It’s the new name for chemistry,’” says OSU physicist Janet Tate. “We’ve been doing nanotechnology for a long time in physics and chemistry. A lot of what we talk about when we teach quantum mechanics is inherently nano in scale.”
Tate grew up in South Africa, received her Ph.D. at Stanford and has won awards for her teaching and research since coming to OSU in 1989. A major focus has been OSU’s transparent electronics initiative, nanoscale research that demonstrated the world’s first transparent thin-film transistor in 2003 and integrated circuit in 2006.
“Transparent electronics is a new field, but it exploits old ideas,” says Tate. It all starts with semiconductors in which the flow of electricity can be easily manipulated. Most semiconductors, such as silicon-based materials in computers, cell phones and other electronic devices, are visible because they absorb light. However, some semiconductors let particles of visible light (photons) sail right through them untouched. Thus, they are as clear as glass.
The trick with invisible semiconductors (indium oxide, zinc oxide, tin oxide and others), adds Tate, is to find ways to make them conduct electricity without making them visible. In her research, she collaborates with Doug Keszler (Chemistry), John Wager (Electrical Engineering and Computer Science) and a team of technicians and students to make transparent semiconductor films that are tens of nanometers thick. By placing other molecules into the films, they hope to achieve the kind of control over the flow of electricity that is now possible with silicon-based semiconductors.
“You inevitably shift off into the fringes where things are not quite as transparent, and you discover that maybe it’s useful for something else like solar cells,” Tate adds.
Common as Wood
That kind of opportunity strikes a chord with John Simonsen, a chemist in OSU’s Wood Science and Engineering Department. After receiving his Ph.D. from the University of Colorado, he worked in the private sector before coming to OSU in 1990. He specialized in wood-plastic composites and wood preservatives. Strength is a problem with composites, he says, especially the bond between wood and synthetic polymers. “They just don’t have the mechanical properties at the cost that we expect for building materials. You have to go to exotic polymers to get strength. You’re talking dollars a pound. Wood costs a dime a pound.”
So he became intrigued when he began learning about the ability of nanosize-cellulose crystals to increase strength in composites. “Cellulose crystals are stronger than steel and stiffer than aluminum. And they’re renewable. That’s probably why nature uses them for trees,” he says.
Just as important for researchers, cellulose chemistry is well known, and, compared to many other nanoparticles, easy to work with. In his lab, Simonsen makes cellulose nanocrystals by grinding standard filter paper, then hydrolyzing it with acid. A simplified version of the process goes like this: Add acid, spin the solution in a centrifuge, then pass it through an ultrafilter to concentrate the cellulose and remove the impurities. The resulting liquid looks like watered-down milk. For show-and-tell, he keeps a vial of the cloudy liquid on his desk, telling visitors that the cellulose has remained suspended in solution for more than a year.
Simonsen uses the material in several areas of research: improving the performance of membranes, such as those in kidney dialysis filters; improving the properties of barrier films to keep out toxic industrial chemicals; and making novel materials by combining the nanocrystalline cellulose with other polymers.
Initial findings from a dialysis membrane study by Simonsen, Sundar Atre (Industrial and Manufacturing Engineering) and Sweda Noorani, a graduate student, showed that by adding only 2 percent cellulose to the membrane, they increased both stiffness and water vapor transport, a property that should foster the ability of the filter to cleanse the blood.
In addition to his research, Simonsen is working with OSU faculty members on a nanotechnology curriculum in the Materials Science Program. A Nanotechnology Processes Option is also available in Chemical Engineering.
While new materials are driving product development, Brian Paul is putting his money on “nanomanufacturing,” the ability to economically structure matter on the nanometer scale. Paul received his Ph.D. from Penn State and is a professor in the OSU Department of Industrial and Manufacturing Engineering. He specializes in bulk microfluidics, a technology that uses channels no wider than a human hair to improve the quality of chemical reactions and heat transfer.
With this technology, close proximity is key; forced into tight quarters, chemicals react quickly and uniformly. Paul and his colleagues in OSU’s Microproducts Breakthrough Institute (MBI) have found ways to sequence systems of chemical mixers, separators and heat exchangers within microchannels. In MBI research, bulk microfluidic technology has already shown promise in making biodiesel and hydrogen and in filtering blood for kidney dialysis. These microsystems are tested in labs on campus and fabricated at the ONAMI Nano/Micro Fabrication Facility on the Hewlett-Packard campus.
But what makes Paul’s eyes really light up is the microchannel synthesis of nanomaterials, such as nanoparticles called “dendrimers.” Named for their tree-like branching structure, these spherical molecules have spacious interiors and functional exteriors that can be tailored to selectively attach to surfaces. They can carry an anti-cancer drug to a tumor or lock onto the HIV virus, thus making it incapable of infecting a human cell.
Trouble is, dendrimers may take weeks to months to manufacture, and they are priced accordingly, from hundreds to hundreds of thousands of dollars per gram. Using bulk microfluidics, Paul says his OSU colleagues Chih-hung Chang (Chemical Engineering) and Vince Remcho (Chemistry) are continuously producing multiple pounds per hour of dendrimer molecules using much less expensive capital equipment, significantly lowering the chemical cost. Moreover, the team can achieve a level of purity unmatched by industrial batch processing.
Arrays of microchannels can also address another concern that is not so nano, says Paul: safety. “Many nanoparticles are readily absorbed through the skin, and their health affects are not yet well understood. Do we really want a supply chain that is transporting them on the highways and rails? Better to transport reagents and produce the particles at the point of use to minimize exposure,” he says.
That would mean manufacturing nanoparticles in distributed reactors instead of centralized chemical plants. “What we’re talking about is distributed and portable production. We’re talking about a new paradigm, manufacturing models that blow away existing industrial scale models of production,” he adds. The challenge is finding ways to build cheap distributed systems to replace expensive centralized facilities.
With a $650,000 grant from the W. M. Keck Foundation, Paul, Chang and Remcho are studying microsystem-enabled dendrimer production, hoping to find new and efficient ways to apply it to a commercial scale.
“I come from a manufacturing mindset. You can’t wait months tying up expensive capital equipment and expect to make a difference. The objective is to deploy,” says Paul.
Other OSU researchers working on nanoscale projects include Greg Rorrer, Goran Jovanovic and Christine Kelly in chemical engineering. And ONAMI is bringing them together with counterparts at the University of Oregon’s Center for Advanced Materials Characterization in Oregon and Portland State University’s Center for Nanoscience and Nanotechnology. Their private-sector colleagues include Oregon-based FEI, Inc., a world leader in electron microscopy, which enables researchers to see at the nanometer scale and even below, into the spaces between subatomic particles.
Together, they are contributing to an economic sector that could be valued at between $1.4 trillion and $2.6 trillion by 2015, according to recent estimates by Lux Research and the National Science Foundation.