UH engineering researchers help create world's smallest nanotube brush

Multifunctional tool accepted to Guinness World Records

University of Hawaiʻi at Mānoa
Mehrdad Ghasemi-Nejhad, (808) 956-7560
College of Engineering
Arlene Abiang, (808) 956-5637
External Affairs & University Relations
Posted: Apr 12, 2006

The smallest nanotube brushes with bristles more than a thousand times finer than a human hair have been created by a team of researchers from UH Mānoa and Renssalaer Polytechnic Institute of Troy in New York. The invention was recently accepted into the Guinness World Records and will be included in the 2007 Guinness Book of Records.

The brushes can be used for sweeping up nano-dust, painting micro capillaries and even cleaning up pollutants in water. Researchers demonstrated that the brushes can also perform as electronic micro-switches where the brush carbon nanotube bristles provide electrical connections as the brush turns using a micro-motor. On a larger scale, the carbon nanotube brushes can conduct electricity when used in electric motors. The strength of the nanotube brushes is resistant to abrasion and pliability, and may prove to be a better replacement to macroscopic metal brushes in high-power motors.

"The secret is in carbon nanotubes, tiny straw-like molecules just 30 billionths of a meter across," said Ghasemi-Nejhad, project team leader, who also directs the Hawaii Nanotechnology Laboratory. "They are incredibly tough and yet flexible enough that they will yield when pushed from the side."

The researchers created the bristles from hot, carbon-laden gas on to threads of silicon carbide finer than a baby‘s hair. Thin coats of gold steer the carbon away from the brush handle and on to the brush head.

The researchers conceptualized the idea of the brushes after realizing a need for a different kind of material in which they could work at the nano-scale. Conventional brush bristles, made of animal hairs, synthetic polymer fibers and metal wires, are flimsy and prone to breaking down at the nano-scale, researchers say. "The small size, strength, elasticity and ability to conduct electricity make carbon nanotubes ideal bristle material at the nano-scale," said Ghasemi-Nejhad.

In addition to Ghasemi-Nejhad, the research team also includes UH Mānoa mechanical engineers Dr. Anyuan Cao, doctoral student Vinod Veedu, and Dr. Pulickel Ajayan of Rensselaer Polytechnic Institute of Troy in New York.

The team‘s work was published in Nature Materials (July 2005) and has since received worldwide media attention.