Abstract:

The topic of this dissertation is the study of the nanomechanical properties of nanotubes. These multi-faceted mechanical materials are able to perform many tasks at the nanoscale for which traditional nanoelectromechanical (NEMS) materials are insufficient. Their high strength-to-weight ratio and layered structure make nanotubes ideal for a number of NEMS applications. One such NEMS application is to create a nanoscale motor exploiting the interlayer sliding of a rnulti-walled carbon nanotube (MWCNT). A key accomplishment discussed in this dissertation is the creation of such a nanoscale synthetic motor. As an introduction to the subject of nanomotors, a review of the wide variety of nanoscale and microscale motors that either occur naturally or have been synthetically created is presented.

The motivation, creation and operation of nanotube based nanomotors are given in this dissertation. Through the fabrication of these devices a number of novel techniques for the manipulation and selective placement of nanotubes have been developed. These techniques enable the placement of nanotubes on predetermined locations, in an aligned fashion and on a variety of devices.

Through the exploration of alternate device architectures and manipulation techniques, the ability to correlate the atomic structure of individual nanostructures with their mechanical, thermal, and electrical properties has been developed. Electron transparent Si3 N4 membranes can now be routinely fabricated for in situ TEM transport experiments. Nanotubes placed on STM tips through the use of in situ SEM nanomanipulators can also be imaged via TEM prior to transport experiments.

We have successfully created and operated MWCNT nanomotors using electron beam lithography techniques. These motors were capable of 360? of movement and could be continually driven for thousands of cycles without any evidence of wear or fatigue. These MWCNT nanomotors demonstrate the great ability of MWCNT to act as NEMS scaffolds. With nanotubes established as promising NEMS enabling elements, the ongoing experiments of our research group on hybrid nanotube-NEMS devices are also discussed. The fabrication of electron transparent devices uniquely positions our research group to be able to fully correlate the structure and behavior of individual nanostructures and hybrid NEMS.