World's Smallest Electric Motor: A Molecule

Researchers at Tufts University claim to have developed the world's first single molecule electric motor.

The device has a diameter of just 1 nm, which is considerably smaller than a 200 nm motor that was considered to be the world's smallest motor up until now.

"There has been significant progress in the construction of molecular motors powered by light and by chemical reactions, but this is the first time that electrically-driven molecular motors have been demonstrated, despite a few theoretical proposals," said Charles Sykes, associate professor of chemistry at Tufts. "We have been able to show that you can provide electricity to a single molecule and get it to do something that is not just random."

Sykes said that they are able to control their motor consisting of a butyl methyl sulfide molecule with a low-temperature scanning tunneling (electron) microscope (LT-STM). The molecule showed carbon and hydrogen atoms "radiating off to form what looked like two arms," the scientists said. By controlling the temperature of the molecule, they were able to change the rotation of the molecule and discovered that "temperatures around 5K, or about minus 450 degrees Fahrenheit, were "the ideal to track the motor's motion" and analyze the data.

While the molecule works as a motor, the scientists said that it would require "breakthroughs" to turn it into a device with practical applications. As the motor spins at much faster at higher temperatures, it cannot be controlled easily.  "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," Sykes said. "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."