Three-dimensional Nanorobotic Manipulations of Carbon Nanotubes

Abstract

A nanorobotic manipulation system with 10 degreesof-freedom (DOFs) is presented and applied in 3-D manipulation of carbon nanotubes (CNTs) by controlling intermolecular forces. Manipulators are actuated with PicomotorsTM (New Focus Inc.) for coarse motions and PZTs for fine ones, and operated inside a scanning electronic microscope (SEM). Resolutions of manipulators are better than 30nm (linear) and 2mrad (rotary) for coarse motions, and within nanoorder for fine ones. Atomic force microscope (AFM) cantilevers are used as end-effectors, and van der Waals forces between them and objects are controlled by applying dielectrophoresis. Individual multiwalled carbon nanotubes (MWNTs) have been picked up on an AFM cantilever, placed between two cantilevers, and bent between a cantilever and sample substrate. As basic building blocks for more complex nanostructures and devices, CNT-junctions are constructed. A cross-junction was constructed with two MWNTs (∼ø40nm × 6μm and ∼ø50nm ö 7μm), and a T-junction was made of two MWNTs (∼ø40nm × 3μm and ∼ø50nm × 2μm). A kink junction is formed by bending an MWNT (∼ø40nm × 6μm) over its elastic limit for 20 times. Force measurements are performed and the flexural rigidity and Young's Modulus of an ∼ø30nm ∼7μm MWNT are estimated in situ to be 8.641 × 10-20Nm2 and 2.17TPa. Such manipulations are essential for both the property characterization of CNTs and the fabrication of functional nanosystems.