The welding of individual carbon nanotubes to other nanoutbes and metal substrates has been performed, on a selective basis, to produce joints of both good electrical conductivity and mechanical integrity, without the need for a joining material. Carbon nanotubes have been manipulated in-situ in the SEM and have subsequently been cut to specific, pre-determined lengths, joined to substrates, or to each other using only carefully applied voltages with limited currents. We have successfully fabricated structures in three-dimensional space that are both robust and electrically active, and contain several nanotubes placed in the order of our choice. This process now allows for the fabrication of bespoke carbon nanotube devices for the prototyping of device performance associated with electronic properties.

 

 

Figure 1: Secondary electron micrograph of the tungsten tips and substrate in the SEM (scale bar is 10 mm).

 

Figure 2:  I-V curves for the nanotube-tip-substrate connection.

 

Figure 3: Nanotube construction of letters A, T and I using six nanotubes. Secondary electron micrograph of nanotube construction (scale bar is 300nm) (a), and its schematic diagram showing order in which the nanotubes were attached and the connections formed (b). The nanotubes were placed in the order shown numerically (1-6) and the connections made in the alphabetical order also shown in the schematic diagram.