Researchers worldwide are striving to apply these nanostructures in electronics, high-resolution displays, high-strength composites and biosensors. A fundamental problem relating to their synthesis, however, has limited their widespread use.

Current methods for synthesizing carbon nanotubes produce mixtures of tubes that differ in their diameter and twist. Variations in electronic properties arise from these structural differences, resulting in carbon nanotubes that are unsuitable for most proposed applications.
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carbon nanotubes first are encapsulated in water by soap-like molecules called surfactants. Next, the surfactant-coated nanotubes are sorted in density gradients which are spun at tens of thousands of rotations per minute in an ultracentrifuge. By carefully choosing the surfactants utilized during ultracentrifugation, the researchers found that carbon nanotubes could be sorted by diameter and electronic structure.