Controlled assembly of carbon nanotube tip for AFM: simulation and experiment

To fabricate an atomic force microscope (AFM) tip with an attached a carbon nanotube (CNT), we simulated dielectrophoresis, which is caused by a non-uniform electric field. We calculated both the electric field and the fluid field in the area between the tip and the electrode below the tip. On the basis of these results, we analyzed the dielectrophoretic force and torque of CNTs dispersed in a fluid. We determined the ideal assembly conditions for achieving a high success rate. Based on the simulation results, then we were able to directly assemble only one of multi walled carbon nanotubes (MWNTs) that were dispersed in the diluted solution on the apex of the AFM tip. We achieved 50% success rate to fabricate CNT tips, and we show how the CNT tip compares with a conventional silicon tip with respect to the imaging of 15 nm gold particles.