Miniature marvels Technology: Scientists are competing to develop micro-products to improve our world. The payoff is worth billions to those who master the technologies first.

THE BALTIMORE SUN

LOS ANGELES -- Rescue workers amid the rubble of the bomb-ravaged federal office building in Oklahoma City last year expressed their anguish at not knowing where to dig for victims.

Only an army of crawling insects could have quickly searched the rubble without risking further death or injury. And what could insects do to help?

Plenty, if they could be commanded by people, said Kristofer S. J. Pister, an electrical engineer at the University of California at Los Angeles. What those rescuers needed was a swarm of mechanical "crickets" capable of penetrating the wreckage until they sensed the warmth, the cries or the movements of the victims. Then they could signal locations of the victims by chirping or sending radio signals.

"Within the next few years," Pister said, "we will build the first synthetic insects." Eventually, they will be made smart enough to do rescue work or military reconnaissance. And they'll be cheap enough to scatter by the dozens across a collapsed building or a battlefield and to discard when their work is done.

In laboratories across the country, engineers, physicists and chemists are developing the kinds of sensors, motors, gears and miniaturized communications needed to build such "microcyborgs."

But they are just a hint of the miniature marvels being developed or now in production:

High-tech factories are producing millions of microscopic accelerometers, tiny silicon sensors that detect the rapid deceleration of a car as it crashes and that deploy air bags before the occupants slam into the steering wheel and dashboard.

Military researchers are developing micro-gyroscopes so small and cheap that they may be used one day to guide common tank shells to their targets as accurately as the electronics in today's million-dollar guided missiles do.

Engineers are creating tweezers and other surgical tools the size of a human hair, small enough to be threaded into the brain to repair life-threatening defects in blood vessels.

Scientists are developing micro-sensors and other components for inexpensive, hand-held analytical devices. Doctors will get lab results more quickly, law enforcement will get on-the-scene DNA profiles from smaller samples, and homebuyers will learn the lead content of house paint in seconds.

Some researchers are pushing even deeper into microscopic realms, dimensions where the width of a human hair becomes a clumsy yardstick, and atoms and molecules are the bricks and mortar. Their work could lead to computers with vastly increased memory and to new metals with unique and valuable properties.

It is an international competition with an economic payoff worth billions of dollars to the nations and corporations that master the technologies first. The university, corporate and defense researchers involved compare what they are doing to the early work that launched the current boom in computers and microelectronics.

In 1946, ENIAC, the world's first electronic computer, weighed 30 tons, contained 17,000 vacuum tubes and filled a 30-by-50-foot room. It cost $486,000 and required six people to run it.

No one would have predicted then that, after 50 years of miniaturization, desktop computers 50,000 times faster than ENIAC would be running in millions of American homes. Computer chips -- the micro-circuitry at the heart of those advances -- are now nearly everywhere in our lives, controlling our cars, our watches, our kitchen appliances, our toys and our televisions.

"Microfabrication has made possible the information age as we see it today," said Marvin H. White, program director for microstructures at the National Science Foundation. In the next century, scientists and engineers believe, those who command microfabrication most effectively "will be at the cornerstone of all our industry," he said.

Why is smaller so much better?

There are several reasons, scientists say. Smaller electronics are faster because electronic signals don't have to travel as far to do their work. They also need less electricity to operate, making them more portable and useful in more varied applications.

And, thanks to physical properties unique to such tiny dimensions, many micro-mechanical devices are far more sensitive and durable than their full-size counterparts.

The scientists involved say they are developing products that will provide greater productivity, a higher standard of living and a stronger national defense.

Modern navigation and targeting systems -- the "smart" weapons that helped win the Persian Gulf war -- demand "enormous computing power and a tiny amount of space to put it in," said Larry Dalton, a chemist at the University of Southern California. "Stealth aircraft wouldn't be possible without the advent of the miniaturization of electronics."

But the real engine driving these technological advances is profit.

The photo-lithographic technology used to manufacture computer chips makes it possible to produce hundreds of intricate devices on a single silicon wafer, driving down the per-unit cost.

It is the relentless miniaturization of complex electronic circuitry that fuels the continuing boom in the consumer electronics industry. Every year or two, the industry doubles the computing power -- as measured by the number of transistors -- on tiny, silicon microchips. The chips are mass-produced, which makes them more affordable. And as each newer, better generation comes along, prices of the older models fall.

It's a continuing technological acceleration first predicted in 1965 by Intel Chairman Gordon Moore when he was an obscure, 37-year-old scientist. It is called Moore's Law now, and he is a billionaire.

As more powerful products come out, and later as their prices fall, consumers feel they must replace their obsolescent equipment. That stimulates the economy again.

"We like to continue to improve technology and reap the benefits," Dalton said.

Researchers around the world are racing to re-create the computer chip's economic magic by applying the same photo-lithographic technology to the miniaturization and mass production of other products.

"You can't build everything with this technology, but, man, if you can, you win big," said Kaigham J. Gabriel, a deputy director in the Defense Department's Advanced Research Projects Agency (ARPA).

Engineers have learned to etch silicon to create mechanical parts such as tiny sensors, springs, flaps, gears, motors, pumps, valves and hinges. They are combining these components and linking them to microelectronic control circuitry -- at times integrating some or all of them on a single chip.

These microelectromechanical systems (MEMS) are leading to products that enable people to put computers into direct contact with the environment for the first time. These new devices can sense and measure force, motion, light, electromagnetism, chemicals and more. Their computer circuitry allows them to make decisions and act on the information.

MEMS ranks "in a list of the top 10 technologies for the Department of Defense and the commercial world," said ARPA's Gabriel.

A Pentagon assessment of the technology last year forecast that the worldwide market for MEMS products would grow from $1 billion in 1994 to $8 billion after 2000. Other estimates in the report predict that it could reach $12 billion to $14 billion by 2000.

In 1994, automobile manufacturers installed nearly 5 million micro-accelerometers, the sensors that trigger deployment of air bags. More than 17 million miniature pressure sensors, worth $200 million, were made and sold for automotive and biomedical uses. The ink jets in many computer printers are also among the MEMS systems being marketed.

Kris Pister's mechanical insects hint at some of the more imaginative microtechnologies and applications that lie ahead.

In his cramped office at UCLA's engineering school, the boyish-looking, 32-year-old assistant professor and professional dreamer shows a photo of his first-born.

It is 1 centimeter (four-tenths of an inch) long, etched from a flat silicon chip. Its legs are three-sided silicon tubes. The legs are laid out flat when they are formed as part of the chip. But they are hinged to fold up like origami into strong, three-dimensional structures.

"Once we start making them, we'll have the beasts assemble themselves," he said.

The legs aren't motorized yet. But that will come. "We've made motors with the force to drive those things. We've made the sophisticated mechanical linkages to couple the motors to the legs," he said. "We've got all the pieces of the puzzle."

MEMS "motors" are not the spinning electrical coils familiar to most people. They are flat, too, and etched from silicon. Driven by electrostatic forces, they are modeled after human muscle at the molecular level, Pister said.

It's a "grab, pull, let go and grab again" mechanism, like a hand-over-hand movement along a rope. Although his microcyborg's motor might pull only 2 microns (two-hundredths of the width of a human hair) per step, he said, "potentially there is no reason why it shouldn't go 10,000 steps per second."

The motor pulls on a tendon, which moves the leg perhaps 10 to 100 steps per second. That would give it a speed of nearly 50 inches per minute -- "comparable to what you would see a little bug doing," he said.

How do you communicate with bugs?

Pister sees one answer in microscopic "corner-cube" mirrors, three micro-mirrors etched from a flat silicon chip and hinged to flip into place on command, forming right angles to each other, like a floor and two walls.

A corner-cube mirror reflects any beam of light back to its source, no matter the angle. But tilt just one of those mirrors and the return beam goes elsewhere. To the person sending the beam, the reflected light appears to switch off.

Such hinged micro-mirrors have been developed. The "on" and "off" signals are easily translated into ones and zeros, a digital data stream capable of carrying detailed information.

So, shine a laser beam on an area where your mechanical insects are crawling with microscopic corner-cube mirrors on their backs. They wiggle their mirrors in response, describing what their micro-sensors "see." More advanced models might "speak" by cellular phone, which scientists at UCLA have reduced to a single chip.

Such micro-robots could be sent to inspect and report back on conditions in places inaccessible to humans, such as "hot" zones of nuclear power plants.

Military planners see them as micro-spies. Gabriel said they could be dispersed undetected across a combat area, their locations pinpointed by global positioning systems. Their individual reports could then be assembled into detailed maps of the positions and movements of enemy troops, or the deployment of chemical weapons.

Such information is "critical to knowing where you are and knowing where the enemy is and where the fronts are," Gabriel said. "MEMS is investing weapons systems and personnel with better information and better ways of acting on it."

Micro-robots may one day be assigned to build other micro-scale devices. Pister has a three-year grant from the National Science Foundation to develop a mechanical bug that could help assemble computer components. With electronic parts getting smaller and smaller, "assembling these things is a major pain," he said.

He envisions robotic sweatshops. "Picture the things termites can do. You can imagine a flow of materials carried by bugs, and something grows up out of nothing."

Building insect-sized robots may turn out to be the easy part, Pister said. "The challenge is how we are going to give them enough programming intelligence to get them to do what we want. These challenges are the things the robotics community has been dealing with for decades."

Programming is less problematic in other MEMS applications. For example, Pister envisions an "instrumented body" with micro-sensor implants continually monitoring the body's performance as if it were hooked up to machines. Signs of trouble, such as elevated blood pressure or high white cell counts, could be detected and reported in regular downloads to a home computer, then transmitted with an alert to a doctor's office.

Or such sensors could be built into beds, at home or in the hospital. "The idea [is] to try to prevent undetected illnesses," Pister said. "Most of the things that knock us down could be prevented if they were to be detected early enough to be treated.

"Parts of this technology are well understood. Other parts are the subject of active research," he said. The body is a harsh environment for such instruments, and "keeping the body happy, and the sensors happy, are still unsolved problems."

MEMS researchers are learning to craft tiny pumps, channels, reservoirs, sensors and valves from silicon, all the components needed to build a new generation of small and relatively inexpensive biomedical instruments. These devices will one day make it possible to analyze DNA, blood, urine or other fluids, in the doctor's office or in the field.

M. Allen Northrup, a chemical engineer at the Lawrence Livermore National Laboratory, has been working since 1991 on a chip-based miniature version of the tabletop DNA sequencing instruments now in use.

The current machines cost $7,000 to $14,000 each and need 90 minutes to run a test. Northrup's prototype contains $65 in parts and completes its tests in 20 minutes.

In ARPA's Virginia office, Gabriel lifts a 6-pound, telephone-sized device from a shelf. It is an inertial measurement unit, or IMU. It measures changes in motion and guides missiles to their targets.

Gabriel describes it as the Porsche of IMUs. Most of its $20,000 cost is in the difficult, precision labor needed to assemble it. For every four built, two are rejected because they fail performance tests.

Within three to five years, he believes, all the capability of the $20,000 IMU will be transferred to a single chip smaller than a fingernail and costing less than $100. The IMU-on-a-chip will leave more room on a missile for fuel or explosives. It would also be cheap enough to use on artillery and mortar shells that now fly "dumb," like thrown rocks.

The tiny IMUs would direct the flight of the shells by moving minuscule fins. Field commanders would be able to destroy targets with fewer rounds, reducing the exposure of troops to return fire and limiting collateral damage and civilian deaths.

And the chips are tough. In tests, Gabriel said, the mini-IMUs have withstood the huge acceleration forces of M1 tank rounds, 30,000 times the force of gravity.

At UCLA, Chi-Ming Ho, a professor of mechanical, aerospace and nuclear engineering, is working on a MEMS-based "smart skin" for airplanes. Applied to critical wing surfaces, it would improve fuel efficiency by sensing microscopic turbulence and "killing" it by raising microscopic flaps wherever such turbulence appears.

Scientists estimate that a 1 percent reduction in drag would decrease airlines' fuel consumption by 20 percent.

In addition, wind tunnel tests have demonstrated that the micro-flaps, acting in concert, create enough aerodynamic force on an aircraft wing to act as invisible control surfaces. One day, scientists say, they might be used to replace the big flaps and control surfaces on airplanes to give military aircraft and missiles maneuvering capabilities in flight that are impossible today.

TECH TALK

Some terms you might want to know

ACCELEROMETER: Mechanical device for measuring changes in motion.

COMPUTER CHIP: A layered rectangle of silicon containing the miniaturized electronic circuits and components that control computers and other devices.

DIGITAL: A language of ones and zeros by which computers communicate and perform calculations.

ELECTROSTATIC: Forces produced by electric charges.

ETCH: To remove certain portions of materials to create patterns on chips.

IMU: Acronym for inertial measurement unit, a device that measures changes in motion to help guide missiles to their targets.

MEMS: Acronym for microelectromechanical systems, which are miniature mechanical devices created from silicon by photo-lithography.

MICROCYBORG: Miniature robot.

MICROFABRICATION: The manufacture of electronic or mechanical devices on microscopic scales.

MICRON: Micrometer, or one-millionth of a meter. A meter equals 3.28 feet. A human hair is about 100 microns in diameter.

NANOMETER: One-billionth of a meter.

PHOTO-LITHOGRAPHY: Process for using light waves to transfer a design onto a silicon wafer.

PHOTORESIST: A material that becomes soluble when exposed to ultraviolet light.

SEMICONDUCTOR: A substance, such as silicon, whose ability to conduct electricity can be switched on or off.

SILICON: The primary ingredient in sand. Purified, used to make computer chips and micro-machines.

TRANSISTOR: A device used for amplification or switching of electrical current. A computer chip may contain millions of transistors.

ULTRAVIOLET LIGHT: Electromagnetic radiation with a wavelength shorter than that of visible light, but adjacent to it on the electromagnetic spectrum.

Pub Date: 7/14/96

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