DOD to Fund New Rice-led MURI Initiative

DOD to Fund New Rice-led MURI Initiative

BY LIA UNRAU
Rice News Staff
April 15, 1999

Developed by Rice University engineers, metal nanoshells lend a chameleon-like
effect to materials and devices due to their ability to manipulate different
types of light. A new $2.5 million initiative, funded by the Department of Defense,
will allow a group of researchers to study and develop the technology.

The Defense Department has chosen to fund a new three-year Multidisciplinary
University Research Initiative (MURI) headed by Rice University, and including
Oklahoma State University and the University of Houston, to study and develop
the nanoshells, their optical and electromagnetic responses and properties,
and commercial applications.

A number of industries could potentially benefit from the development of this
technology, including electronics, energy conservation, construction materials,
biomedicine and health and beauty.

"The wonderful thing about metal nanoshells is that we can tailor them
to have specific optical properties in different spectra of light," said
Naomi Halas, professor of electrical and computer engineering at Rice and principal
investigator of the project. "The particles themselves have these properties,
an overwhelming advantage over other optical structures, because they can be
easily and directly incorporated into coatings and responsive devices."

Metal nanoshells are tiny particles, ranging from about 50 to 1,000 nanometers
in diameter, with an insulating core, such as silica, coated by a thin shell
of conductive metal–resembling nano-sized malted milk balls.

Metal nanoshells can absorb light or scatter light, both in the visible and
infrared spectra. Varying the thicknesses of the shell and the core changes
the way in which the light is manipulated. Simple variations in thickness extend
the controlled electromagnetic wave response from visible light into the far-infrared
and submillimeter-wave spectral regions.

Nanoshells can be chemically attached to a wide variety of materials, including
plastics, liquids, aerosols, epoxies, glasses and even fabrics. New products
could include energy-efficient smart windows, powerful solar collection and
solar cells, coatings for cars, airplanes or buildings, biomedical sensors,
and optical switches, steering light to different points in futuristic computer
architecture.

Nanoshells are capable of responding to an applied electric current and producing
a voltage-dependent optical response. For instance, by changing the voltage
to a visual display panel built with nanoshell technology, the panel could change
colors or transparency.

Led by Halas, the research team is working to design and create the metal nanoshells
and to fully understand their properties and abilities. They will develop arrays,
coatings, films and ultrathin films. The researchers are also studying different
types and combinations of materials to improve upon current inorganic nanoshells
and to develop completely organic nanoshells.

Jennifer West, Rice assistant professor of bioengineering, is working to develop
nanoshell-based all-optical biosensors and biotests. Because near-infrared light
can pass harmlessly through the human body, an implantable sensor that uses
light to monitor chemicals could be used to instantly monitor a range of different
chemicals in the body. In addition, such nanoshell biotesting devices could
be used to check proteins in whole blood, providing a big advantage over current
methods, which are difficult and time-consuming. Customized nanoshell monitors
could allow doctors to look at small amounts of antigens or antibodies and rapidly
determine the health of a patient.

Peter Nordlander, Rice professor of physics, is an expert in theoretical physics
and is studying the electrical transport properties of nanoshells and how they
behave in a variety of environments.

Alex Rimberg, Rice assistant professor of physics, is studying the way electrons
flow around on the nanoshells and how the internal structure can affect its
electrical transport properties.