A dielectrophorestic method has been developed to manipulate, align and assemble one-dimensional nanostructures using alternating-current electric field. Pre-formed carbon nanotubes dispersed in water are assembled into micro-electrodes and sub-micron diameter fibrils with variable lengths from a few microns to over one centimeter.
The carbon nanotubes within the fibril are bonded by van der Waals forces and are well aligned along the fibril axis. This method affords fine control of the fibril length and is capable of parallel fabrication of many probes using the same source. The short carbon nanotubes fibrils have been used as the probes for scanning probe microscopies and the long ones as electrodes and conducting wires. The excellent performance in electric-field induced emission of electrons makes this structure a promising point electron source of high coherence for applications as electron filaments of electron microscopes and related electron emitters.