With the brushes, researchers will be able to sweep trenches in miniature computer chips or clean mirrors used in nano-motors. When coated in absorbent material, the brushes could also soak up particles in contaminated waters.
"Certainly I believe that the brushes would have commercial uses, particularly when micro-technologies become [the] norm in the future," Ajayan said.
Making Brushes
In previous research, Ajayan grew carbon nanotubes using a technique known as chemical vapor deposition. He and his colleagues applied the technique to make the brushes.
The researchers grew the bristles onto a thin brush handle by sticking the handle into a furnace of carbon-rich vapors.
To control the shape of the brushes, the researchers wrapped the fibers in gold, except where they wanted the bristles to attach to the brush. When the brush handle was placed in the furnace, the fibers grew only on the unmasked areas.
In this case, the nanotubes were grown onto handles of silicon carbide fibers, though other materials can be used, Ajayan said.
Using this process, "we could fabricate these miniature brushes in pretty much any morphology you want," Ajayan said. Some of the brushes look like mini-toothbrushes, others like mini-paintbrushes, others like mini-fans.
Each nanotube bristle is tiny, about 30 nanometers in diameter. The handles, however, could be made relatively thick—about the diameter of a human hair—allowing the brushes to be manipulated either manually or with robotic motors.
Ajayan said the bristles might break off used in a particularly abrasive task, such as stirring a highly viscous substance. But in the demonstrations conducted by the researchers, the brushes held up under a variety of sweeping, painting, cleaning, and electric current-carrying tasks.
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