http://www.sciencedaily.com/releases/20 ... 091220.htm
Just before it breaks, the wire has a diameter of only one gold atom. Extremely careful further bending (at the nanoscale) moves the ends a tiny distance away from each other. Although the wires are now separated, the fracture is is not definitive. As soon as it is very, very carefully bent back into position the ends fuse together again.
Although related to the vibrating molecules, the exact cause of this switching behaviour is still unknown. Trouwborst suspects that is has something to do with a phase transition. More research is needed before the switches can actually be used. However, "what is clear," says Trouwborst, "is that it provides new insight on the road to using molecules as functional building elements in the electronics of the future."