In a biological application, the end holding the iron would instead hold, say, an enzyme or piece of DNA capable of reacting with similar molecules in our bodies. The reaction would then cause a current to run through the wire to a computer chip. Dudek hopes to try detecting electrical changes in simple biological molecules as soon as this summer.
Although Chidsey`s lab is not pursuing practical applications for the nanowires, Dudek envisions eventually attaching bits of DNA to the ends of the wires. Blood samples from a crime scene then could be exposed to the wires, where DNA in the blood would bind to corresponding pieces on the wires, sending an electrical signal to a computer chip that could determine whether the DNA is a good match for a particular suspect.
But such applications are far from reality yet because handling nanowires is not at all like handling ordinary electrical wires. This is chemistry: The wires are in solution and they are poured onto the gold plate where the sulfur end sticks, forming a single, invisible layer.
"It`s like seaweed on a seafloor," Dudek says. "The wires are all aligned." By changing the electrical potential in the gold plate, Dudek can observe a current going through all the wires.
To measure the extraordinarily fast speeds at which OPV conducts electrons, Hadley Sikes, also a graduate student in Chidsey`s lab, took the nanowires to Brookhaven. She found that electrons move across the smallest OPV wires in about 20 picoseconds. This is really fast - equivalent to about 340 miles per hour.
Electricity moves through nanowires very differently from ordinary electrical wires. "If you add electrons to a typical metal wire, a domino effect moves them along the wire until they dump out the other end," says Chidsey. The electrons in metal wire move at a constant speed as they bump each other across the wire. Cut the length of a metal wire in half and it will take half as long for elect
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
14-Mar-2001