Laser tweezer traps nanotubes

Scientists use optical tweezers -- light beams that act like wind at very small scales -- to trap and manipulate microscopic objects.

Researchers from Arryx, Inc. and New York University have demonstrated that it is possible to trap and move carbon nanotubes with optical tweezers. This is tricky because nanotubes' diameters are orders of magnitude smaller than the wavelength of light used to move them. The researchers used a wavelength of light that was strongly absorbed by the carbon nanotubes. By strongly focusing the light, the researchers were able to trap the nanotubes.

Carbon nanotubes are rolled-up sheets of carbon atoms that can be smaller than a single nanometer in diameter, and have useful optical, electrical, chemical and mechanical properties. A nanometer is the span of 10 hydrogen atoms.

The method could be used with holographic techniques to create thousands of simultaneous optical traps for manipulating thousands of single nanotubes or small bundles of nanotubes in parallel, according to the researchers. The method could eventually be used to manufacture tiny devices that contain nanotubes.

The researchers have showed that it is possible to pattern clusters of nanotubes into configurations that are likely to have near-term applications as chemical, biological and physical sensors.

The method could be used to assemble nanotube devices within two years, according to the researchers. The work appeared in the May 3, 2004 issue of Optics Express.