Wednesday, November 12, 2008


At the University of Michigan, Researchers has used nanotechnology to create images of Barack Obama, the next president of the United States. Each Obama face is made up of 150 million vertically-aligned carbon nanotubes grown at really high temperatures and imaged with a scanning electron microscope.Carbon nanotubes are tiny hollow cylinders of carbon that are tens of thousands of times smaller than a human hair, but several times stronger and stiffer than steel.

The nanobama structures are made of carbon nanotubes, and the pictures were taken using optical and electron microscopes. Carbon nanotubes (CNTs) are tiny hollow cylinders of carbon; the diameter of a CNT is tens of thousands of times smaller than a human hair, and CNTs are several times stronger and stiffer than steel. CNTs are grown by a high-temperature chemical reaction, using patterns of nanoscale metal catalyst particles arranged in the shapes of the faces, text, and flags that you see in the images. Each face contains millions of parallel nanotubes, standing vertically on the substrate like a forest of trees. If you were standing next to the nanotubes as they grow, and each nanotube was a 1 foot (0.3 meter) diameter tree, the trees would be growing at over 500 miles per hour! The nanobama faces are approximately 0.5 millimeter wide, or about ten times the width of a human hair.

The nanobamas are made as follows, and as shown in the diagram above:-
(1) convert an image of Barack Obama to a line drawing
(2) shrink the drawing and print it onto a glass plate (mask), using a laser system
(3) shine ultraviolet light through the mask, and onto a thin layer of polymer on a silicon wafer, thereby patterning the polymer by photolithography
(4) coat the wafer with a thin layer of catalyst nanoparticle "seeds" for nanotube growth
(5) remove the remaining polymer, leaving the catalyst seeds in the shapes of the nanobamas
(6) grow the CNTs from the catalyst patterns, by placing the wafer in a high-temperature furnace and filling the furnace with a carbon-containing gas
(7) take pictures of the structures, which are barely visible to the naked eye, using electron and optical microscopes

Beyond the nanobama fun, carbon nanotubes and other nanostructures are building blocks for many important technological advances. These include high-performance solar cells and batteries, new methods of diagnosing and treating disease, next-generation computer processors and memory, and lightweight composite materials. Broad awareness and understanding of the widespread benefits, implications, and potential risks of nanotechnology will be essential for its commercial success. Likewise, public and private support for research and education programs catalyzes economic growth and enables continued breakthroughs in energy, medicine, communications, and other vital areas.

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