Researchers at Tufts University have put together a “molecular motor” that is only about a nanometer across. It’s not the first single-molecule motor ever made, but this one, unlike others, can be activated singly by the minute tip of a scanning electron microscope. They’re working with Guinness to get certified as the smallest motor in the world.
This incredibly small machine — and although it really is just a molecule (and not a big one at that), it is a machine — was created by simply stacking a butyl methyl sulphide molecule onto a substrate of copper. The conformation of the molecule ends up sticking the sulphur “downwards”, where it acts as a sort of pivot, with the carbon atoms sticking out on either end.
Add a little bit of charge and it starts to spin. Both directions, as things at that scale aren’t always as consistent as they are here in the Newtonian world, but it tends to go more in one direction than the other, which makes it predictable.
What can they do with this? Not much right now. It’s just really cool. But the researchers note that this is the first such molecular motor that works electrically, and furthermore can be activated singly while another sits idle mere nanometers away. They accomplish this by passing the charge through a scanning electron microscope, which normally uses a stream of electrons as photon analogues to create an image. Now the electrons are simply a current, and one applicable with such precision that it can be pointed at a single atom at a time. The advantages of this make it exciting for nanotech developers and engineers, who can almost certainly use a part like this.
To anyone who has studied microbiology, this might seem rather underwhelming. Our bodies are homes to molecular machines that are almost unbelievable in their sophistication and elegance. But even so, they were not engineered by Man and are difficult to repurpose. Plus, many of them run on ATP or some other chemical fuel, which is nearly impossible to apply with the same level of precision as the current from a scanning electron microscope.
The research was published in the most recent issue of Nature Nanotechnology. You can read the abstract here.