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Nanotechnology

Tangible Advances

A research team led by Chad Mirkin, Charles E. and Emma H. Morrison, Professor of Chemistry and director of Northwestern's Center for Nanotechnology (Evanston, Illinois) developed a method of writing nanostructures with what they have termed "the world's smallest plotter." The device writes multiple lines of molecules, each line only 15 nm or 30 molecules wide and only 5 nm or about 200 billionths of an inch apart. The plotter is based on the researcher's dip-pen nanolithography (DPN) technique. The dip-pen nanolithography draws tiny lines with a single "ink" or type of molecule. The nano-plotter prints multiple "inks," or four different kinds of molecules, side by side while retaining the chemical purity of each line. DPN, described in the January 29, 1999, issue of Science, turns an atomic force microscope (AFM) into a writing instrument. Researchers first apply an oily "ink" of octadecanethiol (ODT) to the AFM's tip. When the tip is brought into contact with a thin sheet of gold "paper," the ODT molecules are transferred to the gold's surface via a tiny water droplet that forms naturally at the tip. The new nanoplotter multiplies this technique, laying down a series of molecular lines with extreme accuracy. While the microfabrication of electronic circuits and other products currently use solid-state or inorganic materials, innovations such as the nanoplotter will direct future technologies toward the use of organic and even biological materials.

Coupling the organic and inorganic, biological engineers at Cornell University (Ithaca, New York) demonstrated the feasibility of small, self-propelled bionic motors that do their builders' bidding in plant, animal, or human cells. Such machines could travel through the body, functioning as mobile pharmacies dispensing precise doses of chemotherapy drugs exclusively to cancer cells, for example. The device, the result of integrating a living molecular motor with a fabricated device at the "nano" scale, is a few billionths of a meter in size. The first integrated motor, a molecule of the enzyme ATPase coupled to a metallic substrate with a genetically engineered "handle," ran for 40 minutes at 3-4 revolutions per second.

Researchers at Rensselaer Polytechnic Institute (Troy, New York) are working with materials comprising common atoms arranged in grains less than 100 nm in diameter—10,000 times smaller than grains in conventional materials. These grains are used as building blocks to create materials with entirely new properties, which the researchers predict could revolutionize everything from drug delivery to sunscreens.

Althought it is still in the early stage of development, not unlike that of computer and information technology in the 1950s, nanotechnology is a rapidly expanding scientific field.

Defense programs in many countries are now concentrating on nanotechnology research programs that will facilitate advances in programs such as those designed to create secure but small messaging equipment, allow the development of smart weapons, improve stealth capabilities, develop specialized sensors (including bio-inclusive sensors), create self-repairing military equipment, and improve the development and delivery mechanisms for medicines and vaccines.

See also Microtechnology.

Resources

Books

Mulhall, Douglas. Our Molecular Future: How Nanotechnology, Robotics, Genetics, and Artificial Intelligence Will Change Our World. Amherst, NY: Prometheus Books, 2002.

Ratner, Mark A., and Daniel Ratner. Nanotechnology: A Gentle Introduction to the Next Big Idea. Upper Saddle River, NJ: Prentice Hall Publishers, 2002.


Periodicals

Bennewitz, R., et al. "Atomic Scale Memory at a Silicon Surface." Nanotechnology 13 (2000): 499–502.


Organizations

National Science and Technology Council. "National Nanotechnology Initiative" [cited March 10, 2003] <http://www.nano.gov/start.htm>.


Iain A. McIntyre

KEY TERMS

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Ballistic transport

—Movement of a carrier through a semiconductor without collisions, resulting in extraordinary electrical properties.

Carriers

—Charge-carrying particles in semiconductors, electrons, and holes.

Epitaxy

—The growth of crystalline layers of semi-conducting materials in a layered structure.

Integrated circuits

—Complex electronic circuits fabricated using multiple growth and lithography/pattern transfer stages to produce many miniature electronic elements on a monolithic device.

Additional topics

Science EncyclopediaScience & Philosophy: Mysticism to Nicotinamide adenine dinucleotideNanotechnology - Nanofabrication Techniques, Theoretical Methods, Conventional Nanoscale Devices, Quantum-effect Nanoscale Devices, Tangible Advances