Scientists at Tufts University have developed smallest electric motor in the world, which could lead to the development of a new range of devices for applications ranging from engineering to medicine.
The engine, created from a single molecule measures one nanometer across, which is one billionth of a meter. This means, the microscopic motor is 60,000 times smaller than a single strand of a human hair, excelling far beyond the current world record held by a 200-nanometer motor.
Single-molecule motors are not new, nano rotors consist of single molecules were presented by researchers in the past and had shown an ability to get individual molecules to respond to stimulus from light or from chemicals.
But the engine developed by scientists at Tufts University is the first of its kind that can be operated with electricity and it has significant advantages over those other technologies.
The research team published a paper detailing the new electric motor in Nature Nanotechnology on Sunday. The team, led by Professor Charles H. Sykes,also plans to submit the breathtaking achievement to Guinness World Records.
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 E. Charles H. Sykes, Ph.D., associate professor of chemistry at Tufts who led the team.
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 and his colleagues were able to control a molecular motor with electricity by using a state of the art, low-temperature scanning tunneling microscope (LT-STM), one of about only 100 in the United States. The LT-STM uses electrons instead of light to see molecules.
They used the metal tip of the microscope to provide an electrical charge to the molecule that had been placed on a copper surface.
The molecule had a sulfur atom at the center and carbon atoms radiating off to form two arms, four carbons on one side, one on the other. In subsequent experiments, such arms could potentially act as interlocking cogs or gears, and as one molecule is powered, it could turn or rotate others in sequence.
These carbon chains were free to rotate around the sulphur-copper bond at speeds of up to 120 rpm. The team then determined that by controlling the temperature of the molecule they could directly impact its rotation.
Scientists found that approximately 5 Kelvin (K), or about minus 450 degrees Fahrenheit (ºF), proved ideal for tracking the motor's motion as direction and speed were affected by temperature.
At higher temperatures, the motor spins much faster, making it difficult to measure and control the rotation. To achieve practical applications, breakthroughs need to be made in the operating temperatures.
That's because as temperatures rise, the motor spins much faster, far beyond the ability of the scientists to measure the rotations. At 100K, a molecular motor spins more than a million times per second, said Sykes.
It's not that we couldn't work at a higher temperature-it's just that too much is happening. At that speed, it's just a blur, added Sykes.
Molecular electric motors can be used in nano-electromechanical systems (NEMS). For instance, coupling molecular motion with electrical signals may allow scientists to build signal delay lines and nano-scale sensors.
The next thing to do is to get the thing to do work that we can measure - to couple it to other molecules, lining them up next to one another so they're like miniature cog-wheels, and then watch the rotation propagation down the chain, BBC quoted Sykes as saying.