(3 of 3)
Medical applications are also being rapidly developed. Researchers at Maryland's Johns Hopkins have made a pill slightly larger than a daily vitamin supplement that has a silicon thermometer and the electronics necessary to broadcast instant temperature readings to a recording device. By having a patient swallow the pill, doctors can pinpoint worrisome hot spots anywhere within the digestive tract. Future "smart pills" may transmit information about heart rates, stomach acidity or neural functions. Says Russell Eberhart, program manager at Johns Hopkins' Applied Physics Laboratory: "This could change the way we diagnose and monitor patients."
Researchers at Tokyo University are pursuing an even more ambitious goal. Working under Iwao Fujimasa, an artificial-heart specialist, a team of 20 scientists is building a robot less than 1 mm (0.045 in.) in diameter that could travel through veins and inside organs, locating and treating diseased tissue. The group hopes to build a prototype within three years for testing on a horse, but the researchers first must obtain gears, screws and other parts 1,000 times smaller than the tiniest available today.
The ultimate fantasy of the miniaturists is tiny robot "assemblers" that could operate at the atomic level, building finished goods one molecule at a time. This is the far-reaching goal of an embryonic discipline called nanotechnology, so named because it would require manipulating objects , measured in billionths of a meter (nanometers). In Engines of Creation, the nanotechnologist's bible, K. Eric Drexler envisions a world in which everything from locomotives to cheeseburgers is assembled from molecular raw materials, much as proteins are created from their amino-acid building blocks by the machinery of a living cell.
Working with microscopic machines presents special challenges to scientists. Not only do they risk inhaling their tools or scattering them with a sneeze, but they also have to cope with a new set of physical laws. The problem of friction, for instance, looms ever larger as parts get smaller. The tiniest dust speck can seem like a boulder. Rotating a hair-width dynamo through air molecules, says AT&T's Gabriel, "is like trying to spin gears in molasses."
But the payoff can be enormous. As electronics manufacturers have discovered, the laws of economics at the micro level are as different as the laws of physics. A manufacturer might spend a small fortune putting hundreds of moving parts and circuits onto a single silicon chip. But when that chip goes into large-scale production and millions of copies are made, the economies of scale take over, and development costs virtually disappear.
Unfortunately, there is a limit to how many transistors can be squeezed onto the surface of a chip. Thus the attraction of micromachines. They give engineers a way to shrink the moving parts of a device rather than trying to shrink its computer controls further. Some experts believe that within the next 25 years micromachinery will do for machines what microelectronics did for electronics. Given the progress over the past quarter-century, that is saying a lot.