While several other nanotech research centers are in planning or under construction across the country, most under the aegis of the federal Department of Energy, BNC's academic setting and constituency make it quite unusual.

"The DOE-funded centers are being built in conjunction with existing government labs and will serve national users," says David Janes, the research program coordinator for the new BNC who also serves as deputy director of the Institute for Nanoelectronics and Computing, a NASA-supported center on Purdue's West Lafayette, Ind., campus. "In contrast, our facility is a university research lab, and although we will have accommodations for outside researchers, that is not our primary mission."

Of the University's 100-plus faculty who will be members of the BNC, many come from predictable fields like electrical engineering, mechanical engineering, biology, and chemistry, while others represent unexpected specialties: nuclear engineering, computer science, bioengineering, agronomy, and veterinary medicine. This convergence is the result of the interdisciplinary nature of nanotechnology, which relies on the tools and principles of many different scientific areas for innovation and discovery.

For example, a group in Purdue's chemistry department is currently working on building gold nanoparticles encapsulated with molecular layers for surface-enhanced Raman spectroscopy, while a physicist is leading an investigation into low-resistance contacts for carbon nanotubes. Janes, an associate professor of electrical and computer engineering, is involved in a project building networks of metallic nanoclusters with molecular species integrated between the clusters in order to dock one molecule to another.

All these endeavors require enabling technologies to proceed.

"It is very hard to interface nanoscale objects with the external world," says Janes. "For instance, you can't see a carbon nanotube with an optical microscope, so how to measure its properties in a macroscopic test apparatus is a large challenge. One of the key issues the BNC will address is the ability to interface nanoscale objects with the macroscale world."

A New Interdisciplinary Campus

The $58-million, 187,000-sf nanotech center is sited on a redeveloped quadrant at the south end of campus in the University's newly founded research complex, Discovery Park. The park will include the Bindley Bioscience Center, supporting collaborative research in biology and engineering; the Burton Morgan Entrepreneurship Center; and, still in the planning stages, the Discovery Learning Center and e-Enterprises Center. It will also increase proximity to the nearby agriculture and life science facilities, bringing these areas closer into the nanotech fold.

By co-locating these cutting-edge technology facilities, Purdue has managed to avoid the need to duplicate features such as faculty offices, large conference rooms, and auditoriums in every single building. An especially strong relationship exists between BNC and the Bindley Bioscience Center, which are linked together by an enclosed walkway.

"During design, we emphasized the concept of these two buildings as one center," says Janes. "We worked out a commonality of lab approaches and furnishings, and refined the mission of each structure. Knowing that the bioscience building would be right next door impacted some of our design decisions."

Discovery Park also signals a new direction in University expansion, creating an interdisciplinary research campus designed to promote faculty interaction by erasing traditional departmental boundaries among scholarly areas.

"It is a new idea for Purdue, as it is for most universities, to expand into an interdisciplinary research campus," he says.

Well-Supported Cleanroom

The two-story BNC is comprised of two wings, front and back. Labs and offices are located along the front, benefiting from the glassed-in, north-facing façade and soaring atrium that captures natural light. The 25,000-sf cleanroom is on the second floor at the rear of the building, supported by a sub-fab underneath.

The sub-fab, a relatively common feature in the corporate environment but much more unusual in a university setting, Janes notes, is basically a mechanical area for the process systems. Looking something like an unfinished basement, it will accommodate vacuum pumps and process gases (many in gas cabinets), and serve as the main distribution level for de-ionized water, house vacuum, house nitrogen, drains, etc.

"The sub-fab is a fairly substantial investment, but an important design feature," remarks Janes. "Having the utilities underneath gives us the flexibility to reconfigure walls within the main cleanroom and shift bay and chase boundaries in order to introduce new equipment and change processes in the future."

The cleanroom itself is subdivided into a large area for microelectronics fabrication, with spaces ranging from class 1000 down to class 10, and a totally segregated 2,500-sf enclosure for biological- and chemical-based self-assembly techniques. Tucked into the cleanroom's northeast corner, where it has its own entrance and gowning area, the chem-bio space has a unidirectional pass-through to receive microelectronics products and a double-sided glove box allowing joint manipulation—for example docking molecular layers onto nanochips.

"Saline solutions are commonly used in biological work, but the silicon-based microelectronics in the main cleanroom cannot tolerate the sodium in these solutions," says Janes. "Even a little salt water on the gown of a researcher can contaminate other devices, so the space is designed to prevent humans from going from one cleanroom to the other without de-gowning."

It is important, however, to keep microelectronics fabrication are separate from the chem-bio space because of the potential for contamination. Containment of level 2 pathogens in the biological cleanroom is accomplished by using bio-safety hoods.

Nanostructure Labs

Another highly specialized environment in the BNC is the series of nanostructures labs located on the first floor. These rooms must provide extraordinarily stable conditions in order to measure and characterize minute particles.

"These are the kinds of labs where we put our atomic force microscopes, our scanning tunneling microscopes, and other probes or techniques that require very high accuracy for positioning, low vibration specs, and temperature control," says Janes.

While some of the nanostructures labs sit on a basic slab or slab on grade, two ultra-high-accuracy rooms feature a keeled slab underneath a walk-on floor that is suspended on air bearings. The air-spring isolated slab supporting these two rooms meets National Institute of Standards and Technology (NIST) A-1 specifications for vibration isolation, using technology that came out of project architect HDR's previous work designing NIST's new metrology facilities in Gaithersberg, Md.

On occupancy, one of the keeled slab rooms will be outfitted with EMI shielding and full temperature control to within 0.1 degree C. To save on construction costs, the other room is set up so that these capabilities can be added in the future.

"Vibration isolation must be built in upfront, but you can retrofit for high-accuracy temperatures by rebuilding the wall system," Janes explains. "Like a thermos with inner and outer jackets, the dual enclosure keeps the walls at the same temperature as the room, preventing any heat loss or gain through the return air."

Air flow is semi-laminar, with exhaust through the side walls. The constant temperature prevents thermal drift, which could cause materials to expand or contract. Scientists enter the high- accuracy rooms to set up instruments and load samples, and then retreat to an external control room during actual measurement after allowing the temperature in the room to stabilize.

Lab Flexibility

The first and second floors of the BNC also house an array of other labs dedicated to specific functions, such as epitaxial growth, electrical and mechanical characterization, wet and dry chemistry and biology, electron microscopy, optical characterization, and the instructional lab for a course in microfabrication. There is also an incubator laboratory on the first floor where corporate partners can pursue their nanotech projects.

To maximize flexibility, the lab blocks are bisected by a service corridor that provides extra storage and access to utilities distributed overhead.

"Our idea here is to have a connection to each of our primary utilities within 20 to 30 feet of a lab without having to go back to the main bunkers or the main sources for a new hook-up," Janes says.

Within the labs, overhead carriers provide outlets for power and other common utilities close to the bench so scientists do not have to worry about accessing plugs in the walls or floor. Moveable casework allows the spaces to be reconfigured fairly readily.

Offices and Interaction Space

The BNC is designed to accommodate approximately 45 faculty or visiting scientists, between 108 and 180 graduate students, and 21 technical/clerical staff. With its location a mile away from the main engineering campus, the Center will provide office space for faculty who need access to the specialized facilities on a regular basis, along with those involved in keeping the infrastructure up and running.

Stretching across the front of the building, the hard-walled faculty offices offer privacy for conversations with students along with natural light from the glass perimeter. Graduate students have accommodations in suites along the back end of the lab/office wing, with natural light entering from a skylight.

Two federally funded nano research and education centers will also make their home in the BNC: the Institute for Nanoelectronics and Computing, a seven-university consortium led by Purdue and sponsored by NASA; and the Network for Computational Nanotechnology, supported by the National Science Foundation. The institutes will occupy center office suites in the corners of the building.

A dozen conference rooms are spread out between the two floors.

In keeping with its mission to create an interdisciplinary community of collaborative scholars, the BNC's physical layout presents many opportunities for casual encounters and impromptu gatherings among building occupants, especially via the atrium and a back commons along the wall toward the cleanroom.

Many of the interior labs have glass walls looking out onto the pedestrian corridor.

"We want people to see what others are doing," says Janes. "If nothing else, it should foster a lot of curiosity-driven conversations."

By Nicole Zaro Stahl

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