Remaking the World One Atom at a Time
In the not-so-distant future, bricks in new homes may repair themselves when cracks appear. Cars may be coated with a diamond-strength layer that will guard against scratches. Doctors might be able to diagnose hundreds of illnesses by placing a droplet of blood in a machine and reading the results in a few seconds.
All those scenarios, and many more, are conceivable through the use of nanotechnology. Nanotechnology works in the world of the small--the very small.
The goal of nanotechnology is to build things the way nature has been doing it for millions of years: atom by atom, molecule by molecule, with a “bottom up†approach.
“Nano†is a prefix used in the science world to mean “a billionth of,†and nanotechnology deals in billionths of meters, the dimensions at which atoms mingle and molecules interact.
The idea is that if humans could tell atoms how to arrange themselves and how to behave, many of the properties of a material could be controlled at will. Just as nature turns the carbon atoms of coal into diamond by changing their arrangement, so can properties such as color, strength and brittleness be determined at the atomic level.
Scientists believe that if they could learn how to make a brick atom by atom, its molecules could also be “instructed†to self-repair when a crack appeared, or to react to humidity in the air by becoming less or more porous.
Nanotechnology thus carries the promise of building anything imaginable--from the tiniest cranes and motors to self-assembling layers of plastic or metal.
Once the stuff of science fiction, these scenarios are becoming plausible thanks to recent advances in the visualization of the world at the nanoscale. New kinds of microscopes and powerful computer simulation programs developed in the past 10 years have revolutionized nanotechnology.
The microscopes not only allow scientists to see atoms, but also help them move atoms around, as in a famous 1990 experiment in which scientists at IBM’s Almaden Research Center spelled “IBM†with 35 atoms of the element xenon.
And today, a team of IBM physicists announced an advance that brings atomic-scale circuitry closer to reality. The development, dubbed “quantum mirage,†demonstrates that information can travel through solid substances without the benefit of wires. See story, A1
The new tools are the “eyes, fingers and tweezers†of the nanoscale world, Eugene Wong, assistant director of Engineering for the National Science Foundation, told members of the House of Representatives at a hearing on nanoscience.
The promise of nanotechnology is attracting increasing numbers of enthusiasts in science, government and private industry.
“The reason why people are accepting this is because there’s real science behind it,†said Tom Schneider, a mathematical biologist at the National Cancer Institute. “We’ll be able to build anything in the future.â€
Leading scientists who met last year at the National Science Foundation said nanotechnology will have a major impact on the health, wealth and security of the world’s people and will be at least as significant as antibiotics, the integrated circuit and man-made polymers were in the 20th century.
In 1998 the White House Science and Technology Council created the Interagency Working Group, a task force from science, industry and the government charged with developing a vision for U.S. nanotechnology in the next 10 to 20 years.
The U.S. government invested $260 million in the technology in 1999. President Clinton has proposed a budget increase of $227 million for nanotechnology research in 2001.
The Interagency Working Group predicts that nanotechnology will lead to advances in such areas as information technology, medicine, environmental science, the automotive industry, energy and national security.
Among the possibilities the group sees:
* In medicine, nanoparticles that will help ease drug delivery. So-called smart devices made of drugs coated in layers of nanoparticles could travel to sites in the body to cure localized cancers or lesions. Prosthetic limbs and artificial organs may be coated with nanoparticles to prevent immune reactions against the implants. Advances in diagnostics are also predicted, as new machines based on protein and DNA detection allow small amounts of blood to be screened for numerous diseases simultaneously.
* In electronics, production of faster and better computers of Lilliputian dimensions. Already in production is a magnetic reader of nanoscale size that reads information from a hard disk. Also in production are prototypes of nano-sized memory chips with a thousand times the storage of current chips.
* In environmental science, nanomembranes that will filter contaminants or remove pollutants, or will be able to detect and detoxify contamination with chemical and biological agents.
Many challenges remain before scientists can unravel the secrets of the nanoworld. According to a recent report by the Interagency Working Group, the field today is “roughly where the science and technology behind transistors was in the late 1940s and 1950s.â€
But with new visualization tools at hand, laboratories across the country are taking leaps in understanding how atoms and molecules can be arranged at will.
A number of laboratories are learning how to make molecules self-assemble in particular patterns, such as pyramids or pillars. This is seen as a crucial step in the quest to build novel materials atom by atom.
Scientists hope to soon make materials out of carbon “nanotubes,†arrangements of carbon atoms lined together like pencils in a box. Such materials would have one-sixth the density of steel, but 50 to 100 times its strength.
“We know how to make them self-assemble [and] coat things,†said Richard Smalley, who works with nanotubes at Rice University. Carbon nanotubes, many predict, may one day coat anything from cars to airplanes, imparting new strength and durability to their surfaces.
Nature has been a master of nanotechnology for millions of years, and scientists like Smalley believe much can be learned by looking at cells. All the enzymes in our cells, he said, are nanomachines that have evolved to perform unique tasks.
“They reached, in their little world, a level of perfection,†he said. “That’s the dream of nanotechnology, to craft stuff at the ultimate level of finesse. Nature, in the form of life, is the master of this game.â€
Nadrian Seeman’s group at New York University is trying to use another biological molecule, DNA, as the building block for three-dimensional objects. His laboratory recently developed a nanorobotic device with two arms made of DNA that can be rotated between fixed positions.
The researchers say the device is a first step toward developing nanorobots that could one day build molecules in tiny nanofactories.
While initial applications of nanotechnology are likely to be modest, there is talk of even more fantastic things. Some say that one day we will be able make everything from scratch, by giving a computer a few elements and instructing it to make anything from a car to an apple.
“It’s not magic,†Schneider said. “The idea is not magic.â€
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The Nanoworld
The prefix “nano†derives from the Greek word for dwarf. In the world of nanotechnology, machines can be the size of tens or hundreds of atoms, and properties such as color, strength and electrical conductivity can be manipulated without changing a material’s general composition.
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Sources: “Nanotechnology: Shaping the World Atom, by Atom†by the National Science Foundation
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