| NEWS & IDEAS |
May 1998
COMPUTER SCIENCE:
The Distinctive Sound of Cholesterol
INTEGRATED ELECTRONICS:
Key to Copper Chips
BIOLOGY:
Keeping an Eye on the Chaperone
WIDE BAND GAP MATERIALS:
Entering a New Information Age
FUEL CELLS:
Unpolluted Power From Hydrogen
ROBOTICS:
Six Arms Do the Job Faster Than Two
COMPUTER SCIENCE:
The Distinctive Sound of Cholesterol
Rensselaer has patented a device that listens to blood flowing in a patient's
carotid artery and tells a doctor immediately if the artery is blocked by
dangerous cholesterol deposits. The device provides an inexpensive, non-
invasive screening system that doctors can use in their offices during routine
checkups.
Michael Savic, professor of electrical, computer, and systems engineering, has
built a working prototype for Sunward Electronics of Delmar, N.Y., which has
been granted a license to market the technology.
The two large carotid arteries in the neck carry blood to the brain. Physicians
now diagnose stenosis -- cholesterol deposits in the arteries -- by using
expensive diagnostic devices or by listening to the sounds made by the blood.
When the heart pumps blood, velocity is high (systolic cycle) and the flow is
turbulent even with no stenosis. If the artery is clean, there is no turbulence
when the heart does not pump (diastolic cycle), and when the velocity of
blood is low. But when cholesterol deposits are present, the flow is turbulent
during both cycles of a heartbeat. An expert can hear the difference.
Savic has developed a number of computer systems that recognize highly
specialized sounds, including a burglar alarm that reacts to the sound of
breaking glass and a detection system that warns if gas is leaking from
pipelines or storage tanks. He suggested that a similar device could
distinguish differences in sounds produced by blood in patients with
cholesterol problems. The system he developed was tested on patients,
producing highly accurate readings.
Contact: Michael Savic (518) 276-6388
INTEGRATED ELECTRONICS:
Key to Copper Chips
Electroplating -- a traditional technique used for such large-scale
manufacturing processes as coating auto bumpers with chrome -- is now
seen by many in the electronics industry as the least expensive way to build
copper connections on computer chips, according to David J. Duquette.
Duquette, professor of materials science and engineering, heads a two-
pronged Rensselaer research program to solve the basic technical problems
industry faces in adopting this technology.
Most interconnects are made with aluminum wires, but as chips get smaller
and more densely packed, copper, which is more conductive than aluminum,
will make it possible to build faster computers. Rensselaer researchers have
worked for years to develop copper technology, and IBM announced in
September 1997 that it had succeeded in building the first chips with copper
interconnects.
If large numbers of chips with copper wiring are to be manufactured at
reasonable cost, however, many technical problems remain to be solved.
Because it creates electrical problems, copper can't be placed directly on a
silicon chip but must be isolated by a barrier layer. It's not possible to
electroplate directly on this non-conductive layer, so an expensive "seed"
layer of copper must be laid down first. Furthermore, as chip sizes decline,
trenches and vias that must be filled with copper are getting narrower,
complicating the problem.
In a new program in Rensselaer's Center for Advanced Interconnect Science
& Technology, Duquette is exploring the basic science of the plating process
and seeking ways to simplify it. He also heads a program sponsored by
Semitool Corporation, maker of the equipment used throughout the
electronics industry for copper plating, to improve the performance of its tool.
Contact: David Duquette (518) 276-6448, duqued@rpi.edu
BIOLOGY:
Keeping an Eye on the Chaperone
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Alpha crystallin, the major protein in the lens of the eye, is a "chaperone"
that protects other proteins from dangerous interactions. When the
chaperone itself goes bad, cataracts may occur, says Jane Koretz, Rensselaer
professor of biology. Koretz has just received a four-year, $1 million
continuation grant from the National Eye Institute for research that includes
the characterization of alpha crystallin, which makes up 50 percent of the
lens.
Most proteins last only days or weeks. But alpha crystallin remains stable for
decades and at the very high levels of concentration needed for refraction.
"That longevity is extremely important. The lens is a bag of locked-in protein.
It is not renewed the way protein is in other parts of the body," Koretz says.
The reason alpha crystallin remains so stable may result from the fact that
this chaperone protein continually keeps a protective eye on its own behavior
and prevents its own self-destructive interactions. If the self-monitoring fails,
crystallized particles appear in the once-clear fluid of the lens. These particles
scatter light, causing glare and difficulty with night driving. The particles may
also cause the lens to be less resilient and less able to focus. In advanced states
the super-aggregated particles may form cataracts.
"What we want to know is why the chaperone fails," says Koretz.
Contact: Jane Koretz (518) 276-6492
WIDE BAND GAP MATERIALS:
Entering a New Information Age
When it comes to hardware, wide band gap materials are at the cutting edge
of information technology, according to Leo Schowalter, professor and chair
of the Physics Department at Rensselaer Polytechnic Institute.
Wide band gap materials, defined by electrical qualities that control the
strength of their bonds, include gallium nitride, aluminum nitride, and
silicon carbide, adds Michael Shur, the Patricia W. and Sheldon Roberts '48
Professor of Solid State Electronics. As scientists and engineers gain the ability
to create pure forms of these materials and use them, they will revolutionize
a range of applications that includes magnetic computer memory and flat-
panel displays, Shur says. They won't replace silicon, but they will do a long
list of new jobs that silicon doesn't handle well.
Wide band gap semiconductor devices are expected to revolutionize the
supply of electric power worldwide if their properties can be controlled
properly. These wide band gap devices promise substantial gains in power
utilization efficiencies and also promise huge cost savings in the construction
of power distribution grids.
Wireless communications will be a major growth area, Schowalter predicts.
In addition to having a wide band gap, nitrides are piezoelectric, which means
they can be made to vibrate at a very exact frequency by applying an electric
field. These materials could be used to multiply the number of cell phone
conversations the airwaves can carry at one time by making higher
frequencies available.
Rensselaer researchers conduct approximately $2 million a year in wide band
gap research, with most of the funding coming from the Department of
Defense and the National Science Foundation.
Contacts: Leo Schowalter (518) 276-6435, schowalt@unix.cie.rpi.edu; Michael Shur (518) 276-2201, shurm@rpi.edu
FUEL CELLS:
Unpolluted Power From Hydrogen
A small tank of hydrogen (about the size of a quart of milk) and a fuel cell
developed at Rensselaer Polytechnic Institute will power your portable
fluorescent lantern non-stop for more than 40 hours. "Or you can wear out
about 80 D-cell batteries," says Scott Ehrenberg of Dais Corporation, a
Rensselaer incubator company that developed the fuel cells in partnership
with Rensselaer's New York State Center for Polymer Synthesis.
The Dais "Power-Cell" uses hydrogen and air to create electricity for laptop
computers, lanterns, cordless power tools, small TVs, and other portable
devices that usually depend on batteries.
"Someday soon fuel cells will power cars and entire homes," says Dais
president Timothy Tangredi '78. "But that technology is a bit further off. Dais
has developed fuel cells to meet real consumer needs right now."
In its smallest size (about as big as a half-gallon of ice cream), the totally quiet,
air-cooled unit can power multiple devices requiring up to 30 watts. When
produced in commercial quantities, this unit would cost about $200 and last
more than 4,000 hours, says Ehrenberg. "The only thing you replace is the
hydrogen that costs about two dollars a cylinder," he says.
In July, Dais will unveil a 2,500-watt unit produced with partial funding from
the New York State Energy Research and Development Authority
(NYSERDA) and the Wright Malta Corporation. Dais is even working on a
device that generates its own hydrogen from rods or pellets that dissolve in
water.
Contact: Timothy Tangredi (813) 942-8353, tnt@dais.net
ROBOTICS:
Six Arms Do the Job Faster Than Two
Better than ambidextrous, a robot created with the help of the Center for
Automation Technology (CAT) at Rensselaer Polytechnic Institute can work
with six arms at one time.
Selmer Bringsjord, associate professor of philosophy and director of the
Software written by CAT researchers enables a circuit board tester being
developed by Integri-Test Corp. of Commack, N.Y., to maneuver six
independent probes. The first commercial test machine is expected to be
available later this year.
The control software acts as a traffic director, explained Sunil Singh,
the CAT senior researcher who led the project. It is an optimization problem
in which you must test all necessary combinations of board features as quickly
as possible, while making sure the arms don't collide.
Circuit boards have traditionally been tested with "bed-of-nails" probes,
with a new fixture needed for each design. Integri-Test introduced the concept
of moving probes. In the tester they now market, a pair of probes can test
for resistance and capacitance between any two points on a board.
This moving tester is particularly useful for small runs, when it is not
cost- effective to build new fixtures for each design. Moving probes also
will be able to test boards when features become too small for bed-of-nails
probes, according to Joseph Conti, Integri-Test president.
Because testing all features on a board with two probes is time-consuming,
Conti obtained a federal Small Business Innovative Research Award and subcontracted
with the CAT to develop the algorithms and write the software for a six-probe
system that would increase throughput and cut manufacturing costs.
With a total of 12 employees, Conti explained, Integri-Test is too small
to afford a research staff of the quality available at the CAT, a New York
State Center for Advanced Technology. If the new product is successful,
he expects employment at his company to double, he said.
Contacts: Harry Stephanou, CAT director, (518) 276-6156, hes@cat.rpi.edu; Sunil K. Singh (518) 276-2243, sunil@cat.rpi.edu
