Electromagnetic waves from palm-sized device penetrate solids without harmful effects of X-rays

[Dave Farber <dave () farber net>]

------ Forwarded Message
From: Dave Mackenzie <davemack () UDel Edu>
Organization: University of Delaware
Date: Mon, 07 Apr 2003 11:18:10 -0400
To: dave () farber net
Subject: Electromagnetic waves from palm-sized device penetrate solids
without harmful effects of X-rays


 Electromagnetic waves from palm-sized device penetrate solids without
harmful effects of X-rays
                   
 1:50 p.m., April 2, 2003--Scientists from the University of Delaware
have made a major breakthrough in
terahertz nanotechnology, one that could have practical applications in
medical imaging, hazardous operations.

 The research team has discovered a way to harness the power of the
terahertz frequencies in a
palm-sized device using a semiconductor nanostructure, according to
James Kolodzey, UD professor of
electrical and computer engineering.

 Terahertz is the “final frontier” in the study of electromagnetic
waves, Kolodzey said, and in the frequency
spectrum it lies between microwaves and infrared light. It is 1,000
times higher in frequency than microwaves,
which are used in cell phones and ovens, and 100 to 1,000 times lower
than visible light.

 “This may revolutionize terahertz technology by making it accessible,”
Kolodzey said. “The device is the size
of a cell phone, perhaps with a side pack for cooling. It can be
portable. Previous terahertz systems were
definitely not portable.

”Not much is known about the terahertz frequencies, Kolodzey said, and
the group’s 
research is both in basic science and in practical applications. It is
known that the frequencies are strongly
absorbed by the atmosphere, which makes terahertz a poor medium for long
distance communication through the air,
which is how the microwave frequencies are used. However, terahertz is
of great value at closer ranges.

 For instance, Kolodzey said, it can be used to detect chemical
compounds, such as pollutants.  Also, it is
sensitive to molecules and, to the researchers’ surprise, can pass
through solid materials and so can be used in imaging and scanning. In
that way, it is like X-rays except that it is not believed to be at all
harmful to humans.

 The ability to scan through solid materials is a unique and new
terahertz operating principle that has not been
explored, Kolodzey said. To date, the UD researchers have scanned a
paper clip through a silicon
wafer and have looked at the interior of an egg by scanning through the
shell.

 Kolodzey said he is excited about the potential uses for the new
nanotechnology, particularly in the medical field
where it could be used to scan for diseases, such as cancer, the cells
of which have a vibrant terahertz signature.
 “With cancer, early diagnosis is important,” Kolodzey said. “This could
help identify  cancer very quickly using
hand-held device.  If you catch it early, it gives doctors more  of an
edge. And, this really highlights the cancer.”

 It also could provide dentists a tool in addition to X-rays and has
applications in the field by providing rescuers
a device that could detect victims trapped under tons of rubble and
emergency and environmental personnel a tool for
stand-off detection of hazardous materials. And, all this in a hand-held
device, not a room-sized piece of machinery.
“Our goal is to make it usable and affordable,” Kolodzey said.

 The devices are based on a silicon germanium semiconductor, Kolodzey
said, adding that UD is one of the primary centers for the study of this
medium in the world.  The semiconductor is used to select energy bands
that relate to terahertz and filters are added to control the frequency
more precisely, “at our will, not nature’s,” Kolodzey said.  A waveguide
is used to corral and distribute the signal in the manner of a laser
pointer, except one with unique powers.

 Kolodzey will give a presentation on the research group’s finding
during the 11th International Symposium on Nanostructures to be held
June 23-28 in St. Petersburg, Russia.

 Also, he has been invited to speak at two events sponsored by the
Institute of Electrical and Electronics Engineers (IEEE). The first, the
fourth IEEE Topical Meeting on Silicon Monolithic Integrated Circuits in
RF Systems, will be held April 9-11 in Grainau, Germany. The second, a
workshop on optical technologies for medical applications, will be part
of the IEEE International Microwave Symposium to be held June 8-13 in
Philadelphia.

The research is funded by the National Science Foundation, the Defense
Advanced Research Projects Agency (DARPA)
and the U.S. Air Force.

Article by Neil Thomas
Photos by Eric Crossan


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