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Big Future for Tiny Sensors


SAN FRANCISCO — It's time to repaint the living room, and you face the usual dilemma: neutral eggshell or a pink cast to reflect the highlights in your new Persian rug?

As you ponder, a cement truck pulls up outside to begin to pour a foundation for a new house across the street. Anticipating six months of construction noise, you consider leaving the color as it is and moving to the country--the living room always seemed too small, anyhow.

If scientists at Xerox Corp.'s Palo Alto Research Center (PARC) are right, micro-electro mechanical systems, or MEMS--devices too small to be seen with the naked eye--will solve such problems with unique elegance.

Spread a can of smart paint on your walls and at the flick of a switch, turn eggshell to pink or back again. Sound-canceling MEMS embedded in the paint will make it seem as though you're in the middle of a pastoral countryside. MEMS won't make your living room bigger, but they'll replace that bulky entertainment center--just paint a new set of speakers and a big-screen TV on your wall.

For the Record
Los Angeles Times Tuesday July 28, 1998 Home Edition Business Part D Page 3 Financial Desk 2 inches; 41 words Type of Material: Correction
Smart Matter--A caption Monday with a photo of scientist Andrew Berlin incorrectly identified a portion of a Xerox Corp. Smart Matter experiment. The pictured object and accompanying detail photo is actually an array of air-jet flaps used to prove the concept of a touchless photocopier.

Smart paint calls to mind the classic children's book "Harold and the Purple Crayon," in which whatever a little boy draws comes to life. But MEMS are no daydream. In 10 to 20 years, these and similarly futuristic applications of MEMS may be possible, if not commonplace.

MEMS consist of computers, sensors and actuators--moving parts--that range from about 10 microns (a human hair is about 75 microns thick) to about a millimeter in length. First created about a decade ago, MEMS are gradually entering the marketplace.

Analog Devices Inc., a Norwood, Mass.-based semiconductor company, uses MEMS to create exquisitely sensitive deceleration sensors for automobile air bags--perceiving the difference between a bump in the road and a head-on collision in which the bag must be deployed in a fraction of a second.

Dallas-based Texas Instruments Inc. takes the concept further with an array of 500,000 individually controllable micro-mirrors that reflect light from within computer projectors used for small-group presentations.

Scientists at Xerox PARC and a handful of other labs across the country are trying to take MEMS to the next level. They want to make matter itself programmable so that it could change dynamically in response to the environment--Smart Matter.

Scientists create MEMS with the technologies used for building microprocessors. (MEMS differ from nanotechnology--almost unimaginably small machines built atom by atom, but whose practical applications depend on elusive scientific breakthroughs that may be decades away.)

The hard part, said Mark Weiser, chief technologist at PARC, is "how do we get them to do something coherent together?"

To that end, PARC has assembled a team of computer scientists, physicists, materials scientists, electrical engineers and robotics experts. Anthropologists are also on board to help determine what kinds of interactions between humans and Smart Matter would make sense. But for now the biggest problems involve packaging, communications and power.

It's one thing to build millions of MEMS. It's another to make them robust enough to operate indefinitely when fixed to a wall, let alone retain their functionality after floating around in a can of paint.

And how do you get a multitude of tiny machines to communicate and work together? One idea involves embedding transmitters and receivers into the mix, but so far no one knows how that would work.

MEMS don't need much power. Light, microwaves, vibration or even a breeze blowing over MEMS cilia could do the job. But a working system hasn't been produced yet.

Such engineering challenges suggest why many near-term applications of Smart Matter will use human-scale materials that are easier to power and coordinate. One such project at PARC: a touchless copier.


'Right now we take delicate sheets of thin pulped wood with microscopic pieces of toner and grab them with powerful rollers. It's not surprising that the paper is sometimes crumpled," said Weiser. And rollers are noisy and limit the speed and accuracy of moving individual sheets of paper, with their fluttery edges and irregularities caused by variations in humidity or temperature.

The solution? An ultra-high-speed printer with a single moving part--a fan. Paper is moved by a multitude of tiny, though not microscopic sensors and air jets, each controlled to shoot air independently but all work in concert. They adjust their flow to move any grade of paper under any environmental condition. The paper never touches the machine between the input and output trays.

PARC scientists have already proved the concept, and a functional device could be ready in as little as two years. More futuristic Smart Matter products are much further out, but that's hardly surprising. Futurist Paul Saffo, a director of the Institute for the Future in Menlo Park, notes that it took about 20 years after the invention of the transistor to figure out how to commercialize it.

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