Nanoprototyping and nanosensors among topics at Nano Assembly

A desktop nanoprinter that can essentially deposit anything on any surface and the development of nanosensors that can function as digital antibodies are two of the topics that will be covered during a Nanotechnology Assembly panel discussion during the International Mechanical Engineering Congress and Exposition in New York City from Nov. 11-16.

The nanoprinter was invented by 27-year-old Brian Hubert, who received a Ph.D. in mechanical engineering from the Massachusetts Institute of Technology earlier this year and was the 2001 recipient of the $30,000 Lemelson MIT Student Prize for excellence in invention and innovation.

Hubert will be a participant in the Nanotechnology Assembly panel discussion, scheduled for Nov. 13.

As Hubert sees it, his nanoassembly machine has the potential of becoming a nanoscale rapid prototyping device that can build virtually anything atom by atom.

"I'm using a purely mechanical process," Hubert said. "This is a mechanical solution to what to date has been a cryogenic physics or a chemistry solution."

The potential for using nanoscale devices as digital antibodies is raised by Phil Kuekes, a nanotechnology researcher at Hewlett Packard Laboratories in Palo Alto, Calif., another member of the Nanotechnology Assembly panel, who will also moderate the discussion.

The panel will be rounded out by George D. Skidmore, manager of the top/down group at Zyvex Corp. in Richardson, Texas. The primary business of the four- year-old, privately held company is developing and commercializing nanotechnology.

"Zyvex has the long-term goal of doing molecular nanotechnology, which means assembly with atomic or molecular precision," Skidmore said. "The top/down effort involves trying to make machinery now at the MEMS scale and scaling it down, in an attempt to build manipulators for nanoassembly and eventually molecular assembly."

Hubert began work on the nano- assembly machine in MIT's Media Lab, while pursuing his doctorate. His goal, he said, was to create "an inexpensive, ubiquitous device that basically sits on every desk and can print out materials at the nanoscale as easily as you can at the macroscale."

In keeping with this goal, Hubert built a machine that, unlike most nano equipment, operates at room temperature and humidity and needs no special vibration protection.

Hubert has used his device, which he refers to as "the world's smallest dot matrix printer," to deposit gold, silver, organic polymers and photoresists in the 50- to 30-nanometer range (a few thousand atoms) in proof of concept tests. That has been accomplished in what Hubert calls 2 1/2 dimensions, meaning he can't create structures taller than they are wide. Eventually, he hopes to build in three dimensions.

Meanwhile, at Hewlett Packard, physicist and computer architect Kuekes is focusing on building electronic circuitry at the nano scale. To do so, he and his colleagues have gone counter to the conventional method of first designing a chip and then manufacturing it. Instead, they first create relatively simple molecular structures that act as bits of memory and then use their knowledge of computer architecture and algorithms to download complex patterns into the memories. In effect, they create the design after the chip is manufactured.

"Essentially, we make what had been a simple crystal into an electronic circuit with lots of complexity," Kuekes said.

Ten-nanometer structures of proteins fold into precisely defined three-dimensional patterns in living systems.

To create these nano circuits, the researchers have taken a page from a currently produced type of micron-size chip known as a field programmable gate array (FPGA). These off-the-shelf chips are used when relatively few are required, and the cost of customizing a fabrication production line is not justified.

FPGAs, which find their way into devices such as fax machines and laser printers, are produced with many logic gates and bits of memory, but the way they are connected is determined after manufacture.

Complex programs and algorithms are used to feed current into the FPGAs in patterns that create the desired connections. "We're copying that same strategy to build nano structures," Kuekes said.

The advantages of adapting this concept to nanoelectronics include economy, versatility and forgiveness. Kuekes said that during the mid-1990s, Hewlett Packard designed its own FPGA chip and put 864 of them together to create a superchip.

"Instead of downloading just the design of one chip, we could download the entire design of any supercomputer we wanted," Kuekes said. That gave them a do-it-yourself supercomputer that runs 100 times faster than a top-end Hewlett Packard workstation, he explained.

The lesson is important for nanoelectronics because when things are built at the nanoscale, the energies of random thermal motion are enough to cause imperfections. "So an architecture that can take advantage of, and work around, defects is going to be very important for building things at the nano scale," Kuekes said.

In partnership with a group at the University of California, Los Angeles, the HP team created and demonstrated the parts of their programmable nanochip, but have yet to incorporate them into a whole. "By the end of the year," Kuekes predicted, "we will have some announcements as to some degree of success there."

As many experts see it, nanoelectronics will be introduced commercially in hybrid chips containing micron and nano features.

In fact, Kuekes and Stan Williams, also of HP Labs, recently received a patent for a method of connecting nanoscale and micronscale devices to each other. With such an arrangement, the reduction in size is dramatic. Kuekes predicted that, within the next few years, his lab will be able to pack as much logic as was available in an early-1970s computer into the space of an intersection of the smallest wires on a conventional chip.

— Victor D. Chase

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