Scientist at Tufts University have developed a single molecule electric motor that measures a mere 1 nanometer across.
The team, led by Professor Charles H. Sykes, plans to submit the uber-tiny electric motor to Guinness World Records, as the current champion weighs in at 200 nanometers. It should also be noted that single strand of human hair measures approximately 60,000 nanometers wide.
“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,” explained Sykes.
“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.”
According to Sykes, the Tufts team managed to control the molecular motor with electricity by using a state of the art, low-temperature scanning tunneling microscope (LT-STM) – which employs electrons instead of light to “see” molecules.
Indeed, the metal tip on the microscope provided an electrical charge 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.
The team then determined that by controlling the temperature of the molecule they could directly impact its rotation. Temperatures at approximately 5 Kelvin (K), or about minus 450 degrees Fahrenheit (ºF), proved to be the ideal to track the motor’s motion.
Although there are foreseeable practical applications for the Tufts electric motor, Sykes acknowledged that breakthroughs “needed to be made” to lower the temperatures at which electric molecular motors operate – because the motor spins much faster at higher temperatures, making it difficult to measure and control its rotation.
“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,” he added.