The recent decade has seen an explosion of optical communication. Yet much of the information processing is conducted electronically since there have been few truly tunable optical devices. Ferroelectric materials offer a potential solution. They possess interesting nonlinear properties that can be used to design and fabricate unique active tunable nanophotonic devices. Photonic crystals are synthetic hetero-structures that provide an unprecedented ability to manipulate light including slowing down and reflecting selected frequencies.
In eukaryotic cells, kinesin motor proteins transport intracellular cargo along microtubules, 25 nm protein filaments that form the cell cytoskeleton. This biomotor transport system is of fundamental importance in cell function and dysfunction, and provides a model system for nano- and microscale transport in engineered systems.
In 2004, a Penn State MRSEC team showed that bimetallic platinum/gold nanorods could swim at speeds up to 20 microns per second by catalyzing the decomposition of hydrogen peroxide. Nickel stripes added to the motors allowed them to be steered using weak magnetic fields as a "remote control". Microgears formed from platinum and gold rotated in hydrogen peroxide solutions. In 2005, MRSEC researchers†have inverted the system: instead of moving catalytic structures through a static solution, a static silver/gold catalytic structure pumps the solution past it.
Frustration is not only a state of mind, but also a state of matter wherein the interactions among different subunits cannot all be satisfied. Ordinary water ice is highly frustrated: there are many many different ways in which the protons within the lattice of ice can be arranged, and all are equally good (or bad, depending on your point of view).
Molecules come in well-defined lengths: Penn State MRSEC researchers have invented a technique called "Molecular Rulers," in which molecular layers of precisely defined widths coat preexisting structures and form templates for patterning new structures with ever-smaller dimensions. Advanced lift-off processing and new bilayer resists, developed in 2005, have dramatically improved the uniformity and sharpness of the nanometer-scale gaps between the parent and daughter structures. These gaps can be tailored with molecular scale precision.
Penn State researchers John Badding, Venkat Gopalan and Vincent Crespi, working in close collaboration with Pier Sazio at the University of Southhampton, have succeeded in a task that at first sight may seem impossible: depositing uniform, dense conformal semiconducting nanowires deep within the pores of microstructured optical fibers.
In MRSEC-sponsored research, Kevin Kelly, Andrew Osgood, Yasuhiro Shirai, James Tour and Yuming Zhao at Rice university have produced a nanometer-scale car with fullerene wheels that rotate about axles and guide the motion of the nanocar across a substrate.