World's smallest electric motor made from a single molecule

 The smallest electrical motor on the planet, at least according to Guinness World Records, is 200 nanometers. Granted, that's a pretty small motor -- after all, a single strand of human hair is 60,000 nanometers wide -- but that tiny mark is about to be shattered in a big way.

Chemists at Tufts University's School of Arts and Sciences have developed the world's first single molecule electric motor, a development that may potentially create a new class of devices that could be used in applications ranging from medicine to engineering.

In research published online Sept. 4 in Nature Nanotechnology, the Tufts team reports an electric motor that measures a mere 1 nanometer across, groundbreaking work considering that the current world record is a 200 nanometer motor. A single strand of human hair is about 60,000 nanometers wide.

According to E. Charles H. Sykes, Ph.D., associate professor of chemistry at Tufts and senior author on the paper, the team plans to submit the Tufts-built electric motor 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," says 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."

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.

The team used the metal tip on the microscope to provide 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 determined that by controlling the temperature of the molecule they could directly impact the rotation of the molecule. Temperatures around 5 Kelvin (K), or about minus 450 degrees Fahrenheit (oF), proved to be the ideal to track the motor's motion. At this temperature, the Tufts researchers were able to track all of the rotations of the motor and analyze the data.

While there are foreseeable practical applications with this electric motor, breakthroughs would need to be made in the temperatures at which electric molecular motors operate. 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 Sykes. "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 Changing Face of Chemistry

Students from the high school to the doctoral level played an integral role in the complex task of collecting and analyzing the movement of the tiny molecular motors.

"Involvement in this type of research can be an enlightening, and in some cases life changing, experience for students," said Sykes. "If we can get people interested in the sciences earlier, through projects like this, there is a greater chance we can impact the career they choose later in life."

As proof that gaining a scientific footing early can matter, one of the high school students involved in the research, Nikolai Klebanov, went on to enroll at Tufts; he is now a sophomore majoring in chemical engineering.

This work was supported by the National Science Foundation, the Beckman Foundation and the Research Corporation for Scientific Advancement.

Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the university is widely encouraged.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Tufts University.

Journal Reference:

Heather L. Tierney, Colin J. Murphy, April D. Jewell, Ashleigh E. Baber, Erin V. Iski, Harout Y. Khodaverdian, Allister F. McGuire, Nikolai Klebanov, E. Charles H. Sykes. Experimental demonstration of a single-molecule electric motor. Nature Nanotechnology, 2011; DOI: 10.1038/NNANO.2011.142

From crankcase to gas tank: New microwave method converts used motor oil into fuel

That dirty motor oil that comes out of your car or truck engine during oil changes could end up in your fuel tank, according to a report presented here today at the 241st National Meeting & Exposition of the American Chemical Society (ACS). It described development of a new process for recycling waste crankcase oil into gasoline-like fuel — the first, they said, that uses microwaves and has "excellent potential" for going into commercial use.

"Transforming used motor oil into gasoline can help solve two problems at once," said study leader Howard Chase, Professor of Biochemical Engineering at the University of Cambridge in the United Kingdom. "It provides a new use for a waste material that's too-often disposed of improperly, with harm to the environment. In addition, it provides a supplemental fuel source for an energy-hungry world."

Estimates suggest that changing the oil in cars and trucks produces about 8 billion gallons of used motor oil each year around the world. In the United States and some other countries, some of that dirty oil is collected and re-refined into new lubricating oil or processed and burned in special furnaces to heat buildings. Chase noted, however, that such uses are far from ideal because of concerns over environmental pollution from re-refining oil and burning waste oil. And in many other countries, used automotive waste oil is discarded or burned in ways that can pollute the environment.

Scientists thus are looking for new uses for that Niagara of waste oil, growing in volume as millions of people in China, India, and other developing countries acquire cars. Among the most promising recycling techniques is pyrolysis, a process that involves heating oil at high temperatures in the absence of oxygen. Pyrolysis breaks down the waste oil into a mix of gases, liquids, and a small amount of solids. The gases and liquids can then be chemically converted into gasoline or diesel fuel. However, the current processes heat the oil unevenly, producing gases and liquids not easily converted into fuel.

Chase and his research team say the new method overcomes this problem and uses their new pyrolysis technology. In lab studies, his doctoral students, Su Shiung Lam and Alan Russell, mixed samples of waste oil with a highly microwave-absorbent material and then heated the mixture with microwaves. The pyrolysis process appears to be highly efficient, converting nearly 90 percent of a waste oil sample into fuel. So far, the scientists have used the process to produce a mixture of conventional gasoline and diesel.

"Our results indicate that a microwave-heated process shows exceptional promise as a means for recycling problematic waste oil for use as fuel," Chase and Lam said. "The recovery of valuable oils using this process shows advantage over traditional processes for oil recycling and suggests excellent potential for scaling the process to the commercial level."

Provided by American Chemical Society (news : web)