Going for gold
1 min read
A researcher from the University of Gronigen claims to have developed the smallest mechanical switch yet. He also believes he has created a previously unseen type of electronic switch.
Marius Trouwborst developed a method to organise gold atoms in such a way that a very tiny mechanical switch could be made – just a single gold atom forms the contact. In addition, Trouwborst constructed a type of electronic switch of the same size.
The method works with a so called break junction. First, a gold wire is fixed onto a strip of flexible plastic. By carefully bending the strip, the gold wire slowly stretches. Just before it breaks, the wire has a diameter of one gold atom. Further bending moves the ends a tiny distance away from each other. Although the wires are separated, the fracture is not definitive. When bent back into position, the ends fuse together.
Trouwborst found that, every time the wire breaks, the atoms in the two ends are reorganised. Finally, the points look like pyramids, with a single atom at the apex. “By moving the two ends back and forth by a distance of 0.1nm,” said Trouwborst, “the switch can be turned on and off.”
He also found that molecules can be ‘caught’ between the ends of the wires and that all electron transport goes through that molecule.
If the voltage through the gold wire is increased, the hydrogen molecule starts to vibrate. At a certain point, the resistance suddenly changes. “You can simply turn the system on or off by making the molecules vibrate or not,” said Trouwborst. “This type of switch has never been shown before.”
