"But the problem with reincarnation is that it's hard to imagine what the storage medium for past lives would be. Not to mention the input-output device. I hesitate to rule it out completely, but I'd need pretty definite proof."
- Arthur C. Clarke

Researchers at the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder (CU) have designed a carbon nanotube knife that, in theory, would work like a tight-wire cheese slicer. In a paper presented this month at the 2006 International Mechanical Engineering Congress and Exposition*, the research team announced a prototype nanoknife that could, in the future, become a tabletop tool of biology, allowing scientists to cut and study cells more precisely than they can today.

For years, biologists have wrestled with conventional diamond or glass knives, which cut frozen cell samples at a large angle, forcing the samples to bend and sometimes later crack. Because carbon nanotubes are extremely strong and slender in diameter, they make ideal materials for thinly cutting precise slivers of cells. In particular, scientists might use the nanoknife to make 3D images of cells and tissues for electron tomography, which requires samples less than 300 nanometers thick.

By manipulating carbon nanotubes inside scanning electron microscopes, 21st-century nanosmiths have begun crafting a suite of research tools, including nanotweezers, nanobearings and nano-oscillators. To design the nanoknife, the NIST and CU scientists welded a carbon nanotube between two electrochemically sharpened tungsten needles. In the resulting prototype, the nanotube stretches between two ends of a tungsten wire loop. The knife resembles a steel wire that cuts a block of cheese.