Electric diode tunes in to plastic.Many polymers are called plastics because of their mechanical flexibility, but these materials are chemically versatile as well. Now, a researcher has used a polymer to remake a basic electronic component--a diode. By adjusting the electrochemical electrochemical /elec·tro·chem·i·cal/ (-kem´i-k'l) pertaining to interaction or interconversion of chemical and electrical energies. e·lec·tro·chem·i·cal adj. properties of the polymer, he makes the diode show a wide range of current-carrying capacities. The device "puts a new tool in the toolbox of electrical engineers This is a list of electrical engineers, people who made contributions to electrical engineering or computer engineering.
Conventional diodes join a semiconductor and a metal, creating a junction that allows current to flow in only one direction. The new diode uses indium phosphide phosphide Any of a class of chemical compounds in which phosphorous is combined with a metal. Phosphides exhibit a wide variety of chemical and physical properties. Phosphides that are rich in metal have high melting points and are hard, brittle, and chemically inert; these as the semiconductor and replaces the metal with polypyrrole, a polymer that conducts electricity (SN: 8/23/97, p. 119). A gold mesh embedded in the polypyrrole acts as the electric contact. Lonergan adjusts polypyrrole's electrochemical properties by essentially making it part of a battery. After attaching electrodes to the gold mesh, lie immerses the device in a liquid source of ions. By applying a small control voltage, Lonergan can "tune" the diode by adding or removing electrons from the polymer. This process changes the diode's current-carrying capacity. "It combines in a single device a collection of properties that you would normally have to get from a whole series of separate semiconductor-metal interfaces," Lonergan says. The tunability of the diode makes it a good platform for exploring the basic "technical aspects of metal-semiconductor contacts," says J. Campbell Scott Campbell Scott (born July 19 1961) is an American actor, director, producer, and voice artist. Scott was born in New York City, New York, the son of George C. Scott, an actor, director, and producer, and Colleen Dewhurst, a Canadian-born actress. of the IBM (International Business Machines Corporation, Armonk, NY, www.ibm.com) The world's largest computer company. IBM's product lines include the S/390 mainframes (zSeries), AS/400 midrange business systems (iSeries), RS/6000 workstations and servers (pSeries), Intel-based servers (xSeries) Almaden Research Center The IBM Almaden Research Center, located near San Jose, California, is one of IBM's largest research centers, specializing in both basic research in material science and applied research in computer storage, where many refinements and improvements were made in hard disc drive in San Jose San Jose, city, United States San Jose (sănəzā`, săn hōzā`), city (1990 pop. 782,248), seat of Santa Clara co., W central Calif.; founded 1777, inc. 1850. , Calif. Scott doubts that the polymer diode will ever replace the conventional ones used today, but he says the new device opens up possibilities for future applications. Polymer diodes could be used as tunable sensors with a range of sensitivities, Scott suggests. They could also form the heart of multiple-state computer memories, says Lonergan. Instead of adopting just two states, as in standard binary computer logic, a tunable diode could exist in several different states. For practical applications, the diode needs several technical improvements, such as an increased electric switching speed and replacement of the liquid ion source with a solid. Lonergan is also planning to conduct more tests on the stability of the device, since frequent electric switching quickly degrades conducting polymers. |
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