|
|
Electrical engineers may soon have a new tool for controlling currents in
electronic circuitry, including computer chips, thanks to the pioneering
research of
Mark Lonergan, a University of Oregon assistant professor of
chemistry.
As reported in a recent issue of Science magazine, Mark Lonergan has
created a "tunable diode," a new type of device for manipulating electricity.
Lonergan's realization of the tunable diode relies on the special properties of
a relatively new class of materials known as conducting polymers. While his
invention doesn't look like much--a glass beaker, some tubes and wires held
together with epoxy--it possesses beneficial characteristics not found in
devices made of more conventional materials.
"The unique properties of this device should open new avenues in the design of
circuitry for the control and manipulation of electrical energy," Lonergan
says. "It will be a useful new addition to the electrical engineer's toolbag."
The manipulation of energy in electrical circuits can be likened to controlling
concertgoers seeking admittance to Portland's Rose Garden. In each case,
specialized structures exert control over the system's traffic flow.
Conventional diodes can be viewed as a kind of turnstile for electricity
(diodes convert alternating current into one-way direct current). Lonergan's
innovation--the "tunable" part of the tunable diode--adds another dimension of
control to the turnstile. In essence, it gives engineers the ability to
regulate not only the direction of flow but, in addition, the pressure required
to pass through the turnstile. If the diode is tuned high enough, only those
fans who are willing to exert a lot of energy on the turnstile will get to hear
the concert.
Engineers have yet to devise specific applications exploiting the unique
characteristics of the tunable diode. Lonergan notes, however, that "if the
tunable diode proves practical, it may one day join the transistor, resistor,
and capacitor as a common component found in a myriad of new electronic
devices. It is a new tool, and the advent of any new tool opens up new
possibilities."
Since inventing the tunable diode, Lonergan and members of his laboratory have
been steadily refining it, bringing closer the day of its application to
real-world engineering problems. But Lonergan is also interested in exploring
further, seeking to unravel the fundamental mysteries surrounding conducting
polymers and to discover other new applications.
From the technological viewpoint, conducting polymers interest Lonergan because
they blend the versatile structural and mechanical properties typical of
plastics with the electrical properties required of active elements in
microelectronic devices. This unique synergy may lead to exciting new
technologies such as computer video displays as thin as a Time magazine
and just as flexible.
"At present, we are investigating the feasibility of making all-plastic
versions of the microelectronic devices commonly found inside computers," he
says.
Another area of Lonergan's interest in conducting polymers is their application
in nanotechnology--the rapidly evolving world of extraordinarily small devices.
He notes that conducting polymers are long chainlike molecules only a few atoms
in width; to some, these structures, with their attractive electrical
properties, hold the promise of being used as tiny wires. At a size a thousand
times smaller than the smallest connections on today's best computer chips,
they could be part of the answer to the continuing effort to make smaller
chips.
"We do our work somewhat in the spirit of inventors," Lonergan says. "We are
really seeking to understand the most fundamental principals that govern the
actions of conducting polymers, but we keep practical applications in mind."