The world's smallest electric motor is comprised of nothing more than a single molecule.
The motor, developed by chemists at Tufts University, measures a mere 1 nanometer across, which makes the reigning record-holder (200 nanometers) look hulkingly massive.
Well... not really.
For perspective, a single strand of human hair is about 60,000 nanometers wide. But beyond being minis cue, the new motor may lead to a new class of devices that could be used in applications ranging from medicine to engineering.
To demonstrate that just one molecue is needed to generate motorized motion, the team provided a charge using a special low-temperature scanning tunneling microscope. Electricity was sent from the metal tip on the microscope to a butyl methyl sulfide molecule that had been placed on a conductive copper surface. This sulfur-containing molecule had carbon and hydrogen atoms radiating off to form what looked like two arms, with four carbons on one side and one on the other. These carbon chains were free to rotate around the sulfur-copper bond.
By controlling the molecule's temperature, researchers discovered that they can alter it's rotation speed. Temperatures around 5 Kelvin, or about minus 450 degrees Fahrenheit, proved to be the ideal to track the motor's motion. In this range, they were able to track all the motor's rotations and analyze the data.
But for foreseeable practical applications, breakthroughs would need to be made in the temperatures at which electric molecular motors operate. Currently, the motor spins much faster at higher temperatures, making it difficult to measure and control the rotation of the motor.
"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," said E. Charles H. Sykes, a chemistry professor at Tufts and senior author on the paper. "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."
The researchers have detailed their work online in Nature Nanotechnology and plan to submit the Tufts-built electric motor to Guinness World Records.
(via press release)
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