Nanoassembly of Carbon Nanotubes through Mechanochemical Nanorobotic Manipulations

Nanoassembly is one of the key techniques for molecular nanotechnology. As an extension of scanning probe microscopes (SPMs) to three-dimensional space and for relatively large nanometer-scale objects, nanorobotic manipulation systems have shown their effectiveness in nanometer-order positioning, picking and placing, property characterization and simple nanoassembly of nanometerscale objects. In this paper, molecular construction through mechanochemical manipulations for nanoassembly is presented by using carbon nanotubes (CNTs) as objects. Because of their well-defined geometries, extraordinary mechanical properties, various electronic characteristics and other extraordinary properties, CNTs have been shown to be one of the most promising materials for nanostructures and functional devices. The potential of engineering application of CNTs to fabricate nanometerscale electronic devices and mechanical systems largely depends on the ability to manipulate them in threedimensional space. Previous works have shown strategies and systems for 3D nanorobotic manipulations of carbon nanotubes, and the nanoassembly of multi-walled carbon nanotubes (MWNTs). However, the components were joined through weak van der Waals forces. Assemblies with higher stiffness can be obtained by using electron-beaminduced deposition (EBID), however EBID works by adding additional materials to enhance the intermolecular forces between objects. Although EBID can provide stiffer links between CNTs, it is still too difficult, if not impossible, to control the deposited materials in atomic scale. With a specially designed experiment, we show that it is possible to link CNTs by forming chemical bonds between them through mechanochemical nanorobotic manipulations without adding any additional material.