Physics & Astronomy Colloquium

3:30 PM, Friday, February 24, 2006

Room 155, Chem-Phys Building

Dr. Bruce Hinds

Department of Chemical & Materials Engineering
Department of Chemistry
University of Kentucky

``Functional Nanomaterials: nm-Scale Shadow Lithography, Molecular Electrodes, and Carbon-Nanotube-Based Membranes''

Due to their micron scale lengths, nanotubes and nanowires can be manipulated with current micro-fabrication techniques yet result in nanometer scale lines. The primary challenge is to control the location and diameter of these nanowires or tubes. An approach investigated here is to utilize the edge of thin film multilayer patterns where the thickness of an exposed face of a catalyst layer determines the diameter of nanotubes grown from it. This can in turn be incorporated into photolithographically defined ``post'' structures for a scalable nm-lithography process. We also use conventional film deposition and photolithography to form an exposed edge of a thin film multilayer structure (metal/insulator/metal). Molecules self-assemble across the exposed edge offering an alternative conduction path through the molecules with angstrom-scale dimensional control. These findings can be the basis for the large scale integration of molecules into electronic devices.

In related work, aligned arrays of carbon nanotubes (CNTs) are incased in a polymer film. After plasma surface treatment, the tips of CNTs are opened to have hollow 7nm diameter cores passing from one side of the polymer film to the other. These membranes show that transport can be gated by chemical interactions at the core entrance. Reversible bio-chemical sensing was also demonstrated. Pressure driven flux of a variety of fluids are highly accelerated, increasing by 5 orders of magnitude from classic Newtonian flow (Hagen-Poiseuille equation). This suggests frictionless interactions between fluids and the surfaces of the graphitic core. Applications of this carbon nanotube membrane include controlled drug delivery, chemical separations and selective chemical detections.

Refreshments will be served in CP 155 at 3:15 PM