Big Future for Tiny Sensors
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.
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.
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‘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.
“One of the forecasting tenets that I live by is never mistake a clear view for a short distance,” Saffo said.
But to MEMS scientists, the prospects seem limitless. At PARC, Weiser envisions movable toner. “The size of a piece of toner is the same as one of these micromachines, about 10 to 20 microns,” he said. Doing electronic books one better, it’s theoretically possible to create toner with mechanical “feet” that would move particles around to display a multi-page document on a single piece of paper that you could fold up and put in a shirt pocket, according to Weiser.
Perhaps the most bizarre Smart Matter idea is one that most Angelenos would welcome--collapsible cars.
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A Smart Matter car would use lightweight materials that actively respond to road conditions and to a crash, Weiser said. Such a car might sense the shape of the object being hit and crumple away from the impact points. He envisions the car of the future as more like chain mail than sheet metal, with each link of chain independently perceptive, independently self-controlled.
Of course, applications like smart paint may be 20 years off, and chain mail cars might never be built. But current technology shows that Smart Matter is hardly science fiction.
Today’s sound-canceling headphones designed for air travel use the same technology PARC envisions for sound-canceling paint. The headphones emit a sound frequency that is the opposite of that emitted by the drone of the engine and the air stream whooshing past the plane.
PARC scientist Andrew Berlin has already demonstrated a way of increasing the load-bearing capacity of beams and bridges using piezo materials.
Piezo materials were originally developed to control vibration in fighter jets. They emit an electrical charge when deformed or vibrated. As well-heeled ski bums know, “smart skis” use piezo technology to let skiers bounce down the most punishing moguls at high speeds with unprecedented control. Bumps and vibrations are absorbed, interpreted by on-board electronics and dissipated as heat.
In Berlin’s experiment, he gradually increases the load on a model train bridge. Sensors feed information to microprocessors that instantly anticipate when and in what direction bridge supports will buckle. Then small piezo actuators press on support beams to prevent a collapse.
“At a very small scale, you can get a very significant increase in strength for certain geometric shapes,” said Berlin. Not that this will lead to lightweight bridges for full-size trains. After all, the sensors and actuators would need a constant power supply. In the event of a power failure, the bridge would collapse.
But the research could help explain why and when parts fail in a wide range of devices. And it has a more profound conceptual implication, Berlin said. “You’ve taken a load off this beam by putting it into the computational world.”
“It blurs the boundary between the digital world and the analog world in which we live,” his colleague at PARC, principal scientist David Biegelsen, explained.
That blurring of the boundaries, according to futurist Saffo, represents a fundamental shift in how we relate to computers--and how they relate to us.
“There are two parallel universes, the physical world and a newer digital world of our own invention. But the two worlds barely touch--they interact through a glass-thin computer screen. Our computers have no idea that there is an analog reality around them,” Saffo said. “Now what we’re doing is giving computers and networks eyes, ears and sensory organs. But we’re not going to stop there, we’re going to ask them to operate on the physical world.”
If he’s right, Smart Matter and related sensor technologies will usher in the next revolution in computing. Instead of tools we control and communicate with through an “interface,” computers will become integral, autonomous parts of common objects--from self-tracking FedEx parcels to ever-present microscopic security cameras embedded into walls and desktops--constantly monitoring and responding to the environment.
Many scientists foresee an age of ubiquitous sensors and distributed computers whose technical and political horizons are not yet visible.
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Not surprisingly, the military is a key benefactor of MEMS research. Its MEMS-based aircraft, a few inches long, may soon put the accuracy of today’s cruise missiles to shame. “Surveillance dust,” in which millions of floating sensors resembling dandelion spores would be cast from aircraft, may soon track troop movements, send decoy signals or check for the presence of biological or chemical weapons.
“For people who feel a little white-knuckled about the pace of change and the effects of computers on our lives,” said Saffo, “grab your seat belt.”
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Times staff writer Charles Piller can be reached via e-mail at charles.piller@latimes.com.
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Micro Machines
Using techniques from chemistry, physics, semiconductor engineering and other fields, scientists are learning to create a range of machines too small to be seen with the naked eye. They expect the tiny devices to have far-reaching effects on the computer industry as well as on everyday life.
Nanotechnology
Largely theoretical today, nanotechnology could eventually allow the creation of self-replicating machines that build products atom by atom or molecule by molecule. The computer simulation (left) depicts a gear mechanism built from carbon and sulfur molecules surrounded by a silicon shell. Lined end to end, up to hundreds of thousands of nanomachines would fit across an inch. Scientists think it will take 10 to 50 years before nanotechnology becomes a reality.
Micro-Electro Mechanical Systems (MEMS)
Combining computers, sensors and tiny actuators, MEMS are created with the same lithography process used to produce microprocessors. MEMS measure from about 25 to many thousands per inch. First created about a decade ago, MEMS are gradually entering the marketplace as sensors for air bags and other precision devices, and in a range of other applications. Texas Instruments created a MEMS-based array (a subsection is pictured bottom left, with an ant’s leg for scale) consisting of 500,000 independently controlled mirrors. It offers ultra-high accuracy for computer-linked image projectors used in group presentations.
Smart Matter
When linked in groups of hundreds to millions, MEMS (as well as small, but not microscopic materials) can be built into large objects like walls or machines in a way that make those objects programmable and dynamic. Smart Matter perceives and responds to environmental stimuli. Some Smart Matter products, such as touchless photocopiers, may be only a few years away. Others, from sound-proofing paint to ultra-light cars that actively crumple away from the point of impact in an accident, may not emerge for decades.
