The dielectrophoretic attachment of nanotube fibres on tungsten needles

The dielectrophoretic attachment of multi-wall carbon nanotubes (MWNTs) on the apex of tungsten needles immersed in a suspension was investigated. Growth of branched nanotube fibrils out of the needle surface was observed when an ac bias with a frequency of 1 MHz was applied. The fibrils finally coagulate to a single nanotube fibre anchored at the tip's apex during a retraction of the tip from the suspension. Because of the very high dielectric constant of MWNTs, a moderate electric field intensity is sufficient for attaching nanotubes on the tip. The former was approximately two orders of magnitude lower than that reported in previous experiments. The diameter of the nanotube fibres can be controlled by the applied voltage