Scientists Envision Progress in Nanotechnology

Scientists Envision Progress in Nanotechnology

NSF grant boosting efforts of Physics, Chemistry researchers

By Mark Sullivan
Staff Writer

Boston College researchers are using a million-dollar grant to devise microscopes smaller than a human hair that can return images of the tiniest components of human DNA or the smallest defects in computer semiconductors.


L-R) Prof. Krzysztof Kempa (Physics), Prof. Michael Naughton (Physics) and Prof. John Fourkas (Chemistry). (Photo by Justin Knight)
Prof. Michael Naughton (Physics), who is teamed on the project with Prof. Krzysztof Kempa (Physics), Prof. John Fourkas (Chemistry), and Senior Research Scientist Wenzhi Li (Physics), compared their nano-scale magnetic microscopy to the technology used by astronomers to record images of outer space - only, in this case, to image inner space.

"When you go to the doctor to get an MRI, you can see an image of your body that reveals muscle tone, and can tell whether and where a tendon is torn," said Naughton.

"Imagine being able to image not only the muscle, but the structure that comprises the muscle, and then the cells in the muscle, and then the DNA in these cells, and then the base pairs that make up the DNA, and then the hydrocarbons that make up the base pairs. Our goal is to invent the tools that will make this possible."

The magnetic sensors will be developed from carbon nanotubes and nanofibers that will increase imaging sensitivity orders of magnitude beyond today's capabilities, Naughton said. A four-year grant of $1.05 million from the National Science Foundation is funding the research, with Boston College providing $70,000 in equipment.

Naughton describes the team's research as a "marriage of scanning probe microscopy and MRI," two technologies that image magnetism, to produce what is called magnetic resonance force microscopy, or MFRM, technology originally conceptualized by University of Washington researcher John Sidles. "Our niche is the nano-scale sensors," said Naughton.

An example of one of the component technologies, scanning probe microscopy, is found in the atomic-force microscope, a silicon microchip that can provide topographic images of molecular surfaces mere nanometers in size. One nanometer is roughly 100,000 times smaller than the diameter of a human hair.

The atomic-force microscope has a tiny sharp tip that acts like the needle of a record player to scan a surface and register an image of its topography.

Naughton offered an imaginative analogy: "Suppose God wanted to know all about the White Mountains, but wasn't able to use his eyes. He reached down from heaven and dragged His finger from east to west, and was able to record how much His finger went up and down and made a topographic map of the White Mountains.

"This is what we do on a nano-scale, rather than a macro-scale. Now suppose you were able to not only scan the mountains, but each tree on the mountains. Suppose God had a way of detecting white birch trees by touch." A magnetic atomic-force microscope, he said, is a variation that allows the detection of certain objects by magnetic force: "If a surface has magnetic items, they are the white birch trees."

MRI, short for magnetic resonance imaging, is familiar as a medical technology that uses radio waves to image internal muscles and organs.

The BC researchers seek to meld the imaging technologies in microscopes that can explore the tiniest of surfaces. "When you put them together, you can do an MRI not just on muscles and tendons, but in microscopic - and ultimately nanoscopic - detail on the cells within muscles, and the DNA within those cells."

Naughton said other potential uses include scanning for defects in semiconductors. "The reason pentium chips that power the speed of computers are getting faster is because they're cleaner, and their defects are smaller," he said. The aim is to develop the equivalent of a biomedical MRI scan to detect flaws that slow the chips.

The researchers aim to build nano-scale microscopic sensors from polymers and from carbon nanotubes.

The latter approach is distinctive in that it involves building the devices from the carbon nanotubes up. A conventional atomic-force microscope is created by whittling a microchip down, said Naughton, but these nano-scale magnetic microscopes will be put together from nano-building-blocks thousands of times smaller than a human hair.

"The advantage is, we start out smaller than they end up," he said. "It's harder to reach the scale from the top down. Smaller devices means access to smaller volumes of material to measure.

"The ultimate detail: We expect to be able to image one atomic spin of a molecule."

 

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