Micromachines' might have big future; Numerous applications evolving for
miniature devices
(Cincinnati Enquirer; 05/03/98)
Tiny machines no bigger than a fingernail, a grain of rice or a red blood
cell have been twirling, buzzing and slithering across the pages of science
fiction and research laboratory benches for years.
Now these Lilliputian gadgets are beginning to enter the real world.
Following on the success of crash sensors in automobile air bags, new
micromachines are being developed to sniff anthrax or nerve gas, to protect
nuclear weapons and to resuscitate laboratory mice.
Enthusiasts say they are the advance wave of a technological revolution
comparable to the introduction of computer microchips.
"Imagine a machine so small that it is imperceptible to the human eye,"
said Al Romig, director of the Microsystems Science, Technology and
Components Center at Sandia National Laboratory in Albuquerque, N.M..
"Welcome to the microdomain - a place where gravity and inertia are no
longer important, but the effects of atomic forces dominate," Mr. Romig
wrote in a description of his lab's work published on the Internet.
Sandia, along with other government and private research centers, designs
"microelectronic mechanical systems" (MEMS) - or "micromachines" for short.
As their name implies, these miniscule contraptions combine both electronic
and mechanical functions in a single device. They are etched out of
silicon, the raw material of computer chips, which can be engineered at
scales of millionths or billionths of an inch.
But unlike a computer chip, MEMS don't just "sit there and think," said
Karen Marcus, director of the MCNC Technology Applications Center in
Research Triangle Park, N.C.
Instead, she said a typical micromachine senses its environment, figures
out what it means, then does something useful, such as inflating an air
bag, steering a ballistic missile or reporting the presence of poison gas.
The first widespread commercial application of micromachines are the crash
sensors used since the early 1990s in automobile air bags. About a tenth of
an inch across, these accelerometers sense a sudden change in a car's
velocity, analyze it and flash a signal to inflate the bag in a fraction of
a second.
Coming next are more advanced mini-detectors that can respond to skids and
rollovers, said Pontus Soderstrom, manager of advanced systems technology
for Autoliv, a sensor company in Auburn Hills, Mich.
Similar motion detectors are being developed for use in computer mice and
in game controllers.
"No more joystick wrist for Nintendo players," Ms. Marcus said. The Air
Force wants to apply similar technology to its missiles, she added.
Some other examples of micromachines now on the drawing boards or in testing
Perhaps the most complex MEMS so far is "Stronglink," a miniature padlock
for nuclear weapons designed by Steven Rodgers, a Sandia engineer. To
unlock it, an operator enters a 24-digit code that steers a pin through a
maze, turns a set of silicon gears with teeth the size of blood cells, pops
up a mirror that relays an optical signal to an electronic switch that -
finally - arms the bomb. One false move by a terrorist would jam the works
of this midget Rube Goldberg device forever.
The Defense Advanced Research Projects Agency is developing a chemical and
biological weapons detection system called "Dognose," an array of delicate
sensors on a silicon chip.
"They're trying to replicate a dog's nose, one of the most sensitive
sensors in the world," Ms. Marcus explained. Hundreds of them could be
thrown out the back of an airplane, she said. If they sniff anthrax or
nerve gas, they would radio a warning to a computer.
Sandia is also experimenting with very small seismographs to detect weapons
explosions. "We could sprinkle them all over the world," said Harry Weaver,
a technology manager in the microelectronics lab.
Engineers at the Massachusetts Institute of Technology in Cambridge are
building gas turbines the size of a shirt button, like miniature jet
engines, that weigh less than half an ounce and generate 10 to 20 watts of
electricity. They could replace the unreliable batteries now used in laptop
computers and other products.
MIT is also designing a "mouse respirator," a tiny version of an iron lung
for laboratory mice suffering breathing difficulties. These strains of mice
take years to develop and cost as much as $200 each, according to Dr.
Chi-Sang Poon, of the Harvard-MIT Division of Health Sciences and
Technology. "Until now, there was nothing available to resuscitate these
mice, which represent a major commitment of research time and money," he
said.
Henry Guckel, a professor of electrical engineer at the University of
Wisconsin-Madison, developed a microscopic pressure gauge that can be
mounted on the tip of a catheter and inserted into the heart to measure its
pressure. The device is already in use in Sweden, Mr. Guckel said.
Another Guckel invention - a set of gears with teeth measuring eight-
thousandths of an inch - is being used in miniature pumps manufactured by a
company in Biel, Switzerland.
Eun Sok Kim, an electrical engineer at the University of Hawaii, is
developing midget microphones and speakers, less than a thousandth
of an inch wide, that generate extremely fine sound waves. Kim said there
is "good potential for commercialization" of his devices in inkjet
printers, hearing aids and other products.
On a slightly larger scale are shrunken versions of Sojourner, the
23-pound, two foot-long rover that cruised the surface of Mars during last
year's Pathfinder mission. NASA is building a one-pound, five- inch
mini-rover to ride a Japanese spacecraft to the asteroid Nereus in 2001.
Its mission is to land on the asteroid, collect samples and return them to
Earth by 2006. "They're running around the lab right now," systems engineer
Stacy Weinstein said.
Further ahead, NASA is considering a fleet of one-ounce, one-inch "gnat
rovers" proposed by Anita Flynn, a robotics expert from MIT. A host of such
little rovers could scatter over the Martian surface, seeking evidence of
water.
Other applications include switches for high-speed fiber optic lines, radio
frequency tuners for wireless communications devices and tiny pumps for
inkjet printers or blood monitors.
Despite the fascination with micromachines, Sandia's Mr. Weaver cautioned
that this is "not a mature technology. Very few of these things are on the
market."
Several small companies trying to make a living off MEMS have gone bankrupt.
"We're just turning the corner," Ms. Marcus said. "The financial community
is starting to warm up to MEMS. We're limited only by the imagination of
the engineers."
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Yakov Horenstein
Milano, Italy
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