Sept. 27, 2005
PHILADELPHIA – Engineers at the University of Pennsylvania
have theorized a means of shrinking electronics
so they could be run using light instead of electricity.
In the search to create faster, smaller and more energy-efficient electronics,
researchers have looked elsewhere in the electromagnetic spectrum, which ranges
from the low-frequency energy used in everyday electronics to the high-frequency
energy of gamma rays, to pass the limits of conventional technology.
In the Aug. 26 issue of Physical Review Letters, currently online, the Penn theorists
outline how familiar circuit elements -- inductors, capacitors and resistors – could
be created on the nanoscale (about a billionth of a meter) in order to operate
using infrared or visible light. The Penn researchers describe how nanoscale
particles of certain materials, depending on their unique optical properties,
could work as circuit elements. For example, nanoscale particles of certain metals,
such as gold or silver, could perform the same function in manipulating an "electric" current
as an inductor does on a circuit board.
Optical electronics would make it possible to create faster computer processors,
construct nanoscale antennas or build more information-dense data- storage devices.
Optical electronics could also have exotic applications that simply are not possible
with conventional electronics, such as the ability to couple an electronic signal
to an individual molecule or the creation of biological circuits.
"The wavelength of light can be measured in hundreds of nanometers and the technology
is now available to create structures that would operate on the same or smaller
scale as the wavelength of light," wrote Nader Engheta, lead author, and H. Nedwill
Ramsey, professor in the Department of Electrical and Systems Engineering of
Penn's School of Engineering and Applied Science. "Our work is theoretical, of
course, but we do not foresee any sizable barriers to our plan to make these
circuit elements in the near future."
Before they could describe how to create optical circuit elements, Engheta, his
coauthors and students Alessandro Salandrino and Andrea Alù had to first
envision how nanoscale materials might interact with light. To do so they looked
at a property critical to basic wave interaction called permittivity, which describes
how a particular substance affects electromagnetic fields. If a small sphere
is created, about a few tens of nanometers across, they explained, light would
affect it differently based on its permittivity.
According to their models, the theorists demonstrated that nano-sized sphere
made up of a nonmetallic material such as glass with permittivity greater than
zero would act like a miniaturized capacitor. A nano-sized sphere made up of
a metallic material such as gold or silver with a permittivity less than zero
would act like a miniaturized inductor. Either material could also function like
a miniaturized resistor, depending on how the optical energy is lost in it.
"So now we have three basic elements of a circuit," Enghata said. "Stacked one
upon the other, you could create fairly advanced combinations of circuitry. It
is even possible to use these elements to create 'nano' transmission lines and
"For years, conventional circuit elements have been the basic building bloc in
making functional circuits at lower frequencies," Engheta said. "But now we have
the tools to push back the limits of speed and power on electronics. This technology
could have innumerable applications for consumer products, advanced instrumentation
and even medicine."
news officer, science and engineering
University of Pennsylvania
Office of University Communications
An Invitation to the Penn Media Seminar on Nanotechnology
The Nanotechnology Era is upon us, but few people, it would seem, have a real
understanding of what all this "nano" stuff really is anyway. What, amid the
hype, speculation, and outright fear mongering, is this new science? More important,
how will it affect our lives?
To help you answer these questions, we are inviting you to the University of
Pennsylvania's Media Seminar on Nanotechnology at Penn's Nano/Bio Interface Center
the morning of Tuesday, Oct. 18 , in Philadelphia. The seminar will provide a
primer on the state of the art of nanoscale technology, focusing on the reality
of the science and how it is now being applied in medicine and materials science.
The seminar will be followed by lunch at the World Café Live, with Dr.
Arthur Caplan discussing the ethical implications of nanotechnology research.
The tentative agenda and the list of speakers are below. Please contact Greg
Lester at 215-573-6604 or .
8:30 a.m.: coffee and greetings at the Nano/Bio Interface Center, LRSM Building,
33rd and Walnut streets, Philadelphia.
9 a.m. to 11:30 a.m.: The Basics of Nanotechnology, featuring brief discussions
of the science of nanotechnology and hands-on demonstrations in Penn's nanotechnology
Lunch at the World Café Live (3025 Walnut
St.) with Penn bioethicist Arthur Caplan
Dawn Bonnell, Ph.D ., Professor of Materials Science and Director of theNano/Bio
Dr. Bonnell is focused on the fundamental basis of property variations at atomic
scales in complex materials and exploiting these variations to make functional
Arthur Caplan, Ph.D ., Professor of Bioethics, Chair of the Department of Medical
Ethics and Director of the Center for Bioethics.
Dr. Caplan's research interests are in transplantation research ethics, genetics,
reproductive technologies, health policy and general bioethics.
Yale Goldman, Ph.D., M.D ., Professor of Physiology. Director of the Pennsylvania
Muscle Institute and Associate Director of the Nano/Bio Interface Center.
Dr. Goldman investigates biophysical, physiological, chemical and structural
properties of muscle proteins.
Alan “Charlie” Johnson, Ph.D ., Associate Professor of Physics and Astronomy.
Dr. Johnson's research is aimed at understanding the new transport phenomena
that result when materials and electronic circuits are made on the nanometer