Nanotribology for Nanomanufacturing

It is possible to mechanically construct devices from nanoscale building blocks by actively guiding specific atoms or nanoscale objects into targeted locations in a top-down fashion. Currently, there are few methods to quantify nanoscale frictional energy dissipation associated with such processes in a nanomanufacturing setting.  Obtaining a fundamental understanding of such dissipative forces will be required to enable nanoscale construction of future devices via the manipulation of atomic-scale building blocks.  In this project, we are building a customized atomic force microscope (AFM)-based system designed to characterize nanoscale friction forces; i.e., nanotribology.  With this system we will perform the measurements needed to establish control of the precise forces and energies associated with assembly of nanoscale structures, with the goal of enabling future nanomanufacturing processes.

This project is a collaborative effort that combines expertise in systems and control, nanopositioning, micro- and nanofabrication, small force measurements, vacuum and controlled environment technology, sample preparation, and theory and modeling.  The foundation of the experimental work will be an AFM-based system for research, development, and fabrication of nanoscale devices and future prototypical nanomanufacturing processes.  The challenge in developing such a highly functional system is to combine and adapt a subset of imaging techniques into a single instrument that also performs manipulation tasks.  A primary goal is to combine capabilities for multiscale, three-dimensional (3-D) imaging and metrology with 3-D assembly of nanoscale objects.  These capabilities will enable us to measure their properties and assess their functionality in situ and in real time during their assembly.

Frictional forces play an important role in nanoassembly applications.  Small parts are constructed either by picking up and depositing material or by moving individual objects to their target locations.  Consider a cantilever or nanobot sliding a nano-sized diamond crystal along a surface.  Previous experiments have shown that the mass of the surface-terminating molecular species on this particle or substrate can determine the amount of frictional energy dissipation that will occur, with higher mass correlating with lower friction.  The overall resistance to sliding can be varied depending on the surface chemical termination or other controllable properties, and therefore determines how much effort is required of the cantilever or nanobot as it pushes the object along a surface.

We will perform fundamental measurements of atomic- and nanoscale forces on scientifically and technologically relevant materials and systems, including engineered nanostructures and electronically active surfaces.  Determining the contributions to these forces from individual material properties, including electrical conductivity, thermal conductivity, structure, and composition will fuel investigations into novel methods for controlling tip-sample interactions.  This research will make possible the opening and closing of nanoscale energy dissipation channels and thereby enable novel schemes for nanoassembly.