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What is nanotechnology? You'll get different answers depending on whom you ask. But broadly speaking, nanotechnology is the art of manipulating matter at the atomic scale. It crosses and unites academic fields such as physics, chemistry, biology and even computer science.
What's agreed about nanotechnology? That it is a technology in its infancy, and that it holds the potential to change everything. What's disagreed is nearly everything else: what it will make possible, when those possibilities will be realized and even whether to pursue nanotech at all. People also disagree about what nanotechnology is: Are polymers nanotechnology? What about gene splicing? And many companies tack "nano" to their name with little science to back them up.

Here every guide to nanotechnology pauses to explain the word's exotic prefix. Derived from the Greek word for midget, "nano" means 10-9, a billionth part. A nanometer (abbreviated nm), for example, is one billionth of a meter. An atom measures about one-third of a nanometer. The diameter of a human hair—a measurement notable, perhaps, as nanotechnology's greatest cliché—is about 200,000 nm.

Having explained the prefix, it wouldn't do to overlook the workaday root. Nanotechnology is not just the study of the very small, it is technology: the practical application of that knowledge. Since Democritus, scientists have pondered atoms, but only in the last few decades have they begun to pick them up and put them where they want.

Nanotech Executive Summary provides an overview of nanotechnology's history, what you might find in the nanotechnologist's toolbox, and what scientists are building—and hope to build—with those tools. Finally, it lists further resources: major research centers, government initiatives, private companies, organizations and publications leading the nanotechnology revolution.

Small History

In 1959, the physicist Richard Feynman advised his colleagues: "There's plenty of room at the bottom." In this speech, he envisioned a discipline devoted to manipulating smaller and smaller units of matter. "I am not afraid," he wrote, "to consider the final question as to whether, ultimately—in the great future—we can arrange the atoms the way we want; the very atoms, all the way down!"

This visionary salvo is widely regarded as the first scientific discussion of nanotechnology. It wasn't until 1974, however, that the term itself was coined, by Norio Taniguchi at the University of Tokyo. Taniguchi distinguished engineering at the micrometer scale—so-called micro-technology—from a new, sub-micrometer level, which he dubbed "nano-technology."

For another decade, nanotechnology remained far from the public consciousness. Then, in 1986, MIT researcher Eric Drexler wrote Engines of Creation, the book widely credited with taking nanotech mainstream. Ironically, the newfound public enthusiasm for nanotechnology hurt the field's reputation among some academics, who linked it with pseudoscience and futurology.

At the same time Drexler was writing his book, researchers at Rice University were studying a bizarre molecule. By vaporizing carbon and allowing it to condense in an inert gas, Richard Smalley's research team observed that the carbon formed highly stable crystals of sixty atoms apiece. They suspected the crystals shared the familiar soccer-ball structure used in architect R. Buckminster Fuller's geodesic domes, and named their discovery "buckminsterfullerene," which was quickly shortened to "fullerene," or "buckyball."

The buckyball remains nanotechnology's most famous discovery. It earned Smalley and his colleagues the 1996 Nobel Prize in Chemistry, and cemented nanotechnology's reputation as a cutting-edge research field.

Nanotechnology Toolbox

There is a simple reason why nanotechnology did not emerge as an experimental science before the 1980s: no tools existed to allow scientists to observe—let alone manipulate—individual atoms. This changed in the early 80s, with the invention by IBM researchers of two new microscopy techniques: atomic force microscopy (AFM) and scanning tunneling microscopy (STM).

Both these techniques were a radical departure from previous types of microscopy, which worked by reflecting either light (in the case of optical microscopes) or an electron beam (in the case of electron microscopes) off a surface and onto a lens. But no reflective microscope, not even the most powerful, could image an individual atom. To do so, the new techniques use a cantilever to "read" a surface directly, the way a record player's needle reads a record.

Atomic force microscopy works by passing the cantilever—so sharp that its tip is composed of a single atom—within a few nanometers of a surface. The atomic forces exerting a pull on the cantilever are measured to create an atom-by-atom topographical map.

Scanning tunneling microscopy is similar, but measures a quantum effect called tunneling. STM's cantilever carries a tiny charge, and classical physics says that a wall of potential energy should prevent the charge from jumping to the surface. But when two atoms come close enough, quantum rules let electrons "tunnel" through that wall; STM measures these escapees to map the surface. STM won its inventors the 1986 Nobel Prize in Physics.

By modulating the voltage at the cantilever's tip, scientists can use these techniques not only to see atoms, but also to push and pull them into place. They are both the jeweler's glass and the ball-peen hammer of nanotechnology. But a significant part of nanotech research involves the creation of nanoscale patterns, which requires a finer tool than a ball-peen hammer.

That tool is e-beam lithography. Unlike photolithography, the technique used to make microchips, e-beam lithography is not constrained by the wavelength of light. Using a beam of electrons from a scanning electron microscope, researchers can etch details as fine as a few nanometers.

Big Goals

Today, nanotechnology labs focus on basic research. But they hope one day to apply their discoveries to nearly all branches of technology. Already, research points to revolutionary advances in materials, pharmaceuticals and information technology.

Research that built on Smalley's buckyballs led to the discovery of crystal carbon tubes, similar in structure to buckyballs, but many thousands of atoms long. Excellent conductors with amazing strength, the tiny tubes come in all manner of shapes, sizes and electrical properties. That has led scientists to envision a wide range of applications—from nanoscale electronics to super materials, to tiny machines.

A carbon nanotube is a sheet of carbon atoms joined in a pattern of hexagons and rolled into a cylinder, like chicken wire. Where the two ends wrap around and meet determines the conductive properties of the nanotube. Line the ends up one way, and the nanotube conducts electricity like a metal. But line them up another way, and the nanotube behaves like a semiconductor. Roll one nanotube around another, and you get a multi-walled nanotube—a metal-type inside a semiconductor inside a metal-type, for example.

Using semiconducting nanotubes, researchers have assembled several basic electronic components, including transistors, the electronic logic gate at the heart of all computing. Labs also report success with other nanomaterials, such as silicon nanowires. This is exciting news for the semiconductor industry, which expects to hit the theoretical limit of photolithography within a decade.

Nanoscale approaches to computing, such as molecular computing—which uses single-molecule switches to process data—and quantum computing—which uses single electrons—offer hope that integrated circuits can continue to keep up with Moore's law, which predicts that circuit size will halve, and speed therefore double, every 18 months.

Other research groups are exploring the intersection of nanotechnology and biology, looking for ways to recognize and control the biomolecules that govern normal as well as diseased cell activity. Implantable, intracellular sensing systems, together with custom DNA chips and smarter drugs, promise to transform biomedicine into a much more precise discipline than it is today.

But nanotechnology's greatest advantage—the ability to manipulate individual atoms—is also one of its greatest hurdles. To be practical in the real world, nanotechnology must scale up—way up. Today, researchers assemble nanodevices one molecule at a time. But to be useful, a device would have to incorporate millions of molecules, precisely arranged.

To this end, researchers are exploring "self-assembly": molecular designs that automatically arrange themselves into the desired pattern or device. DNA has been called the perfect example of a self-assembling machine: a single molecule that, under the right conditions, creates not only replicas of itself, but incredibly complex organisms.

Nanotech Resources

International
European Research Area
Nanotechnology Research Institute (Japan)
PHANTOMS

U.S. Government
National Nanotechnology Initiative
Department of Defense
Department of Energy
National Aeronautics and Space Administration
Environmental Protection Agency
National Institute of Biomedical Imaging and Bioengineering
National Institute of Standards and Technology
National Science Foundation

Universities
Harvard University
Nanotechnology at Harvard
Charles Lieber Group

MIT
Nanostructures Laboratory
Nanostructured Materials Research Laboratory

Northwestern University
Institute for Nanotechnology

Princeton University
Nanostructures Laboratory

Rice University
Center for Nanoscale Science and Technology
Richard Smalley

University of California
California Nanosystems Institute

Yale University
Nanotechnology Laboratory

Companies
Hewlett-Packard Quantum Science Research
IBM Nanoscale Science Department
Zyvex

Organizations
Foresight Institute
NanoTech Investor

News & Journals
Nanodot
Nanotechnology
Small Times
Virtual Journal of Nanoscale Science and Technology