Attractive measurement

Engineers at Purdue University have shown how researchers might better use tiny hollow fibres called multi-walled carbon nanotubes to more precisely measure structures and devices for electronics and other applications.

Researchers attach the tubes to the ends of atomic force microscopes. Conventional silicon tips used on the microscopes are shaped like inverted traffic cones. They are fine for measuring relatively flat surfaces, but they do not readily penetrate crevices that often exist in tiny devices and structures, said Arvind Raman, an associate professor of mechanical engineering at Purdue.

The silicon tips also wear out quickly, reducing image resolution, whereas the carbon nanotubes have been shown to retain their accuracy after many hours of use, said mechanical engineering doctoral student Mark Strus.

But while nanotubes better penetrate the nooks and crannies of nano-structures, the flexible tubes often stick to the sides of these structures due to attractive forces between individual atoms called van der Waals' forces.