There are two major problems with creating nanoscale Innerspace-like craft that course through our vascular system: finding a small enough source of power — batteries are large, clunky, inefficient things — and, by association, autonomous control. We have written about nanobots before, but don’t be deceived: they are, for the most part, completely dumb and have to be controlled by magnets outside the body, by an incredibly steady-handed surgeon.

What we really need, if we want nanobots that can actually self-assemble into helpful swarms, is a nano-scale motor that can be driven with a tiny amount of power — and that’s exactly what researchers at Tufts University in Massachusetts have done. They have taken a single butyl methyl sulfide molecule — C 5 H 12 S, just 18 atoms in total — and turned it into an electric motor that can be discretely controlled by a stream of electrons. The molecule mounts itself on a piece of copper, via adsorption, with the sulfur atom acting as a pivot — and by applying a stream of electrons from a scanning tunneling microscope, the molecule begins to spin at up to 120 revolutions per second.

With a total diameter of just one nanometer, not only is this by far the smallest electric motor in the world (and the team has already contacted the Guinness Book of World Records for certification), but because the power source is a microscope — the directional tip of the electron microscope is an electrode in the motor — the entire process can also be visualized and confirmed in real time. Most importantly, though, the electron microscope is so accurate that single-molecule motors can be turned on and off. “People have found before that they can make motors driven by light or by chemical reactions, but the issue there is that you’re driving billions of them at a time — every single motor in your beaker,” says Charles Sykes, one of the chemists behind the discovery. “The exciting thing about [this] electrical [motor] is that we can excite and watch the motion of just one, and we can see how that thing’s behaving in real time.”

The next step, according to Sykes, is to line up a bunch of molecules “so they’re like miniature cog-wheels,” to confirm that these mini electric motors can actually be turned into machines. There’s no mention of what process will be used to arrange these molecules in a sensible fashion, though — and it doesn’t sound like it’s within the realm of standard lithographic processes — and more problematically, a scanning tunneling microscope is generally the size of a room. Still, nano-wire batteries now exist, and our ability to fabricate atom-by-atom structures is improving every day…

In other words, we’re unlikely to have nano-engine ships busying themselves with dispensing targeted cancer drugs or shoveling cholesterol from our arterial walls for a little while yet, but we now know it’s possible.

Read more at BBC and Nature Nanotechnology