The World's Smallest Electric Motor is Made of Only One Molecule

The world of electric motors is about to get a little bit smaller – no, make that a lot smaller. A team of researchers at Tufts University have successfully created an electric motor that’s made out of only one molecule. Its total size? About one nanometer. This advance isn’t the first single-molecule motor, but it’s the first to be electric powered, and that gives it some advantages that other motors, which are either driven by chemicals or light. The use of electricity allows for more precise control and a broader range of applications.

As described in their paper in Nature Nanotechnology, here’s how it works: the researchers used a butyl methyl sulfide molecule as their “motor.” As you can see in the figure on the left, the sulfur atom is in yellow, and the remainder of the molecule is composed of a chain of four carbons to the right, and one to the left. The molecule rests on a copper surface, and it’s powered by an electron from a scanning tunneling electron microscope. The electron is fired at the sulfur atom, causing it to spin.
That doesn’t sound like much right now, but the team hopes to be able to create interlocking molecular chains, so that when just one molecule is powered, it will turn others. That will enable some interesting uses, particularly the manipulation of fluids through small channels for medical applications. If successful, there may be some nanotechnological applications as well.