SUPER SENSORS MAY SHAPE 21ST CENTURY.

Byline: John Markoff The New York Times

At Xerox Corp.'s research center in Palo Alto is a remarkable model, a miniature structure covered with a wired web of sensors that look like small baby-bottle nipples. Working together, sensors like these may someday enable buildings or highway overpasses to adjust instantly so that they dance in harmony with an earthquake, rather than crumble under its tectonic force.

This is cutting-edge research to be sure - and highly pragmatic here, three miles from the San Andreas Fault. But nimble buildings are just one possibility that researchers envision for a little-known but promising technology called micro-electro-mechanical systems.

These Lilliputian sensors, motors, nozzles, valves or other mechanical systems will be able to sense heat, light, motion and sound. Placed on the surface of computer chips, these tiny devices will also be smart enough to interpret what it all means and take action.

Some of the more intriguing applications now in the lab include an airplane wing that can maneuver without the aid of either ailerons or rudders. Instead the skin of the wing has a ``peach fuzz'' of 1/5-millimeter sensors. Controlled by computers, these minuscule flaps can monitor the air sweeping across a wing in flight and respond in concert to stabilize or even turn an aircraft.

Other futuristic applications include substitutes for paint that fill in cracks or release a fire retardant when exposed to heat, automobile bumpers that repair themselves and sensors embedded in a cellular telephone that could pinpoint the user's location.

Increasingly sophisticated micro-electro-mechanical systems, known as MEMS, may soon be making their way into so many elements of everyday life that many scientists and engineers believe they could eventually have an impact as profound as that of the microchip.

``The 1980s were defined by the microprocessor, and cheap lasers have made possible the communications advances of the 1990s,'' said Paul Saffo, a computer industry consultant at the Institute for the Future in Menlo Park. ``The first decade of the next century is going to be shaped by MEMS.''

Micro-electro-mechanical systems are already much more than a futuristic vision. An estimated $2.2 billion worth of these devices are sold annually for use in products like automobile air bags and home blood-pressure kits. And a commercial market is seen emerging for inexpensive chemical analysis instruments - the equivalent of a chemical laboratory on a chip.

Especially in the wake of disclosures that troops during the Persian Gulf war were exposed to toxic residue from destroyed Iraqi munitions dumps, the Pentagon is anxious to have inexpensive, portable means for detecting chemical and biological weapons.

With MEMS, researchers hope to replace cumbersome $17,000 laboratory spectrometers - instruments that measure light waves to determine the chemical composition of substances - with $20 devices that could easily be carried by foot soldiers.

Typically, the goal with MEMS is either to replace existing devices with cheaper, more efficient technology, or to develop entirely new capabilities that were once simply beyond the reach of earlier electro-mechanical technologies.

In less than a year on the market, for example, a $7 MEMS sensor from a company called Analog Devices has become the leading motion detector used in automobile air bags. The sensor, which instructs the air bag to inflate, consists primarily of a microscopic whisker of silicon that can detect a car's sudden deceleration when it hits an object. The Analog Devices sensor is not only less than half the price of earlier mechanical sensors, but industry engineers say it is much more reliable.

And a new type of projection-television system, with much brighter, sharper pictures than previously available, has a MEMS-based video-display system developed by Texas Instruments. The projector is powered by an array of millions of microscopic controllable mirrors floating on a single silicon chip called a digital light processor.

Projection systems that are based on the technology, used primarily for business conferences in auditoriums and other large-audience settings, are now being sold by manufacturers, including Electrohome, In Focus Systems, Nview and Proxima.