Shaping nanoelectrodes for high-precision dielectrophoretic assembly of carbon nanotubes

To achieve high-precision dielectrophoretic (DEP) assembly of carbon nanotubes (CNTs) for nanoelectronic circuits and nanoelectromechanical systems (NEMS), a technique is investigated both theoretically and experimentally for shaping the local geometries of nanoelectrodes to control the electrohydrodynamic behavior of CNTs. Motion trajectories and positions of CNTs assembled on electrodes are predicted based on calculated DEP forces and torques. Both simulation and experimental results show that the geometries of two opposing electrodes significantly affect the precision and robustness with which CNTs can be deposited. Experimental investigation of an electrode array demonstrates that the spacing between neighboring electrode pairs should be larger than twice the width of electrodes to avoid overlapping electric fields and unstable DEP forces; otherwise, unequally distributed electric fields and DEP forces induce a significant number of assembly failures in the array.