World's tiniest electric motor is one billionth of a meter long

The current world record holder for "world's smallest motor" comprises several molecules, but it measures just 200 nanometers across; that's pretty tiny, considering that the average strand of human hair is about 60,000 nanometers wide. But now a team of chemical engineers at Tufts University have developed an electric, nanoscale motor out of a single molecule. Oh, and did we mention it's just one nanometer across?

The diagram up top will help you visualize how it works. The motor was anchored to a slab of copper (orange in the diagram) by a sulfur atom (labeled yellow). Bound to the sulfur atom are carbon and hydrogen atoms (labeled in gray and white, respectively) that project out in opposite directions from the sulfur atom like a pair of mismatched arms. The molecular name for the nanometer-wide motor is butyl methyl sulfide.

The scientists — led by Tufts University chemist E. Charles H. Sykes — then used a scanning tunneling microscope (which uses electrons instead of light to image objects at an atomic level, you can see the conical tip of the microscope in the image up top) to supply the motor with a power source in the form of electrons; when the current passes through the butyl methyl sulfate to the copper plate, the motor converts the electrical energy into rotational energy, causing the carbon and hydrogen arms to rotate around the vertical sulfur-copper bond.

According to the researchers' article, which appears in the latest issue of Nature Nanotechnology, the molecule's current design requires that it be operated at a ridiculously cold temperature (about minus 450 degrees Fahrenheit) in order for the scientists to control, track, and analyze its motion. But according to Sykes, their new motor represents a huge step in the right direction for nanoscale motors, and heralds advances in everything from medicine to communications tech:

Once we have a better grasp on the temperatures necessary to make these motors function, there could be real-world application in some sensing and medical devices which involve tiny pipes. Friction of the fluid against the pipe walls increases at these small scales, and covering the wall with motors could help drive fluids along...Coupling molecular motion with electrical signals could also create miniature gears in nanoscale electrical circuits; these gears could be used in miniature delay lines, which are used in devices like cell phones.

Via Nature Nanotechnology
Top image via E. Charles H. Sykes et al