Teeny-tiny wires capable of connecting with the kinds of molecules that make up the human body could be building blocks for what may be among the first nanotechnology applications: biological sensors for detecting glucose levels in diabetics, measuring hormone levels in menopausal women or identifying DNA at crime scenes.

Stanford chemists have taken an important step toward making such wires by synthesizing a material that conducts electricity faster and farther than earlier designs.

In the Feb. 23 issue of the journal Science, chemistry Associate Professor Christopher Chidsey, graduate students Stephen P. Dudek and Hadley Sikes, and several scientists from Brookhaven National Laboratory report the synthesis of organic molecules that conduct electricity about twice as far as the best such wires previously tested, and at least 3,000 times faster. The so-called "nanowires" made of oligophenylenevinylene, or OPV, are about 50,000 times shorter than a human hair is wide.

The Chidsey lab`s earlier attempts to make nanowires produced a substance called oligophenyleneelthynylene, or OPE, which conducts electricity pretty well for about 3 nanometers (billionths of a meter). For practical applications, though, nanowires may need to conduct electricity farther. That`s why Chidsey looked for a new material.

Chidsey and his students suspected that OPE`s structure was not ideal for conducting electricity because it tends to twist, preventing easy movement of electrons. OPV, on the other hand, is nearly flat, with electrons in a cloud above and below the plane. Its planar structure may explain why OPV conducts electricity so much better than OPE.

To make the wires, Dudek strung single units of OPV into 1 to 5 unit chains that were about 1 to about 4 nanometers long. At one end of the wire is a sulfur atom that can stick to a gold plate. At the other end is an iron-laden molecule capable of giving and receiving electrons.
'"/>

Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
14-Mar-2001