Word: silicones
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With the advent of silicon gears, springs and cantilevers, machines will become smaller still. These miniature moving parts can be etched on silicon using a variation on the photolithographic technique used to make computer chips. To build a tiny rotating arm, for example, layers of polysilicon and a type of glass that can be removed with acid are deposited on a silicon base. A hole for the hub is lined with the glass and then filled with polysilicon. When the glass is etched away, the hub remains and the arm is free to spin around its axis...
Sensors like those made by Delco were the first to combine microelectronics and micromachines on one chip. The typical microsensor is a thin silicon diaphragm studded with resistors. Because the electrical resistance of silicon crystals changes when they are bent, the slightest stress on the diaphragm can be registered by the resistors and amplified by electronic circuits...
...prices drop, these devices will become ubiquitous. By 1995 the typical car may contain as many as 50 silicon sensors programmed to control antilock brakes, monitor engine knock and trigger the release of safety air bags. Similar sensors are already employed in the space shuttle Discovery to measure cabin and hydraulic pressures and gauge performance at more than 250 separate points in the craft's main engines...
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...
...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...