A
team of scientists from Stanford University is testing a new “tricorder”
technology able to remotely detect abnormal matter, such as buried plastic
explosives or even early stage cancers in humans, by manipulating microwaves
and ultrasound.
The
new “radio frequency (RF)/ultrasound hybrid imaging system,” the brainchild of
Assistant Professor Amin Arbabian and Research Professor Pierre Khuri-Yakub,
was designed for remote detection of embedded objects in a number of different
kinds of matter, including water, soil and tissue.
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It
was developed by the Stanford electrical engineering team as part of the
Defense Advanced Research Projects Agency (DARPA) project aimed at developing a
system to detect plastic explosives (IEDs) hidden underground that metal
detectors are unable to pick up.
The
main task of the team, who recently presented their research at International
Ultrasonics Symposium in Taipei, was to create a detection mechanism that would
not touch the surface, so as to avoid triggering an explosion.
To
make their “tricorder” technology “hear” hidden objects, researchers developed
a technology based on basic principles of physics – namely that electromagnetic
stimulation makes material expand and contract, and that this “expansion and
contraction” generates ultrasound waves that can be detected at the surface.
“In
a potential battlefield application, the microwaves would heat the suspect
area, causing the muddy ground to expand and thus squeeze the plastic. Pulsing
the microwaves would generate a series of ultrasound pressure waves that could
be detected and interpreted to disclose the presence of buried plastic explosives,”
Stanford said in the press release.
To
allow the detection process to be carried out from a distance, the Stanford
team built “capacitive micromachined ultrasonic transducers” to differentiate
the difference in sound waves transmission in solid objects and air.
“What
makes the tricorder the Holy Grail of detection devices is that the instrument
never touches the subject,” Arbabian said. “All the measurements are made
through the air, and that’s where we’ve made the biggest strides.”
The
scientists believe that the ability to detect objects remotely will greatly
advance methods for detecting tumors in patients. So far their experiments have
shown great potential.
The
Stanford team used microwave pulses to heat a flesh-like tissue – with an
implanted sample “target” –from about a foot away. The heat caused the target
to contract and to send out ultrasound waves that were then measured by
scientists without touching the “flesh.”
“We
think we could develop instrumentation sufficiently sensitive to disclose the
presence of tumors, and perhaps other health anomalies, much earlier than
current detection systems, non-intrusively and with a handheld portable
device,” Arbabian said.
The
team believes that their technology will eventually be more portable and less
expensive than all other alternatives.
“We’ve been working on this
for a little over two years,” Khuri-Yakub said. “We’re still at an early stage
but we’re confident that in five to ten to fifteen years, this will become
practical and widely available.”
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