What the world's tiniest 'monster truck' reveals

August 23, 2017
Ohio University's nano-sized monster truck led to a curious finding. Credit: Eric Masson, Ph.D.

The world's shortest race by distance—a fraction of the width of a human hair—was run on gold and silver tracks, and took a whopping 30 hours. Given that the vehicles were invisible to the naked eye, your typical racing fan might have missed it. But the April "nanorace" was a huge success for scientists working at the nanoscale. It spurred interest in molecular machines and led to a surprising new discovery, reports the team that entered a nano-sized "monster truck."

The researchers are presenting their nanocar research today at the 254th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features nearly 9,400 presentations on a wide range of science topics.

"The overarching goal was to advertise nanoscience to the public," Eric Masson, Ph.D., says. "Then there was the technical challenge of manipulating multiple nanocars at the same time using a scanning tunneling microscope, or STM, instrument. Additionally, every team had its own goal. Ours was to see if we could deposit an intact supramolecular assembly onto a surface, and control its motion."

Masson and Saw-Wai Hla, Ph.D., co-led the team from Ohio University. They designed and built the largest car at about 3.5 nanometers in length. Officially called the Bobcat Nanowagon, it had a pseudorotaxane H-shaped frame with four relatively large cucurbituril molecules as wheels. Because of the size, it was ironically dubbed a monster truck. But unlike normal vehicles, it didn't have a motor. So to move the nanocar, the researchers used the STM instrument in Hla's lab.

"We incorporated positive charge receptors in the car," Hla says. "So if we injected a in the STM tip pointed at the car, there would be repulsion, and the car would move. We found it worked very well."

The competition, billed as the first-ever nanocar race, was held at the French National Center for Scientific Research (CNRS) in Toulouse on April 28. Six teams from three continents entered their molecule-sized racers. But because the STM instrument in Toulouse only had four tips that could each control only one nanocar, the Ohio team kept their nanowagon in Hla's lab but "drove" it remotely from CNRS.

"My understanding is that this was a first," Hla says. "We manipulated the car at the atomic scale from half a globe away."

Hla and Masson's nanowagon traveled 43 nanometers on the gold track before it got stuck due to a particularly rough section of the track and a power blip in the Midwest. Although it didn't complete the course, it went farther than three other contestants, earning the team a third-place showing.

Masson and Hla say the Ohio team uncovered something intriguing as a result of the race. They had assembled the nanowagon by suspending the chassis molecules in water, adding the wheel molecules and then evaporating the water. About 70 percent of the resulting structures looked like two-wheeled hover boards, a few had three wheels, and about 10 percent had all four wheels. They were surprised to find that very few wheels weren't connected to anything.

"That means that it was easier to break the chassis, a covalent bond, than to break the noncovalent bonds between the chassis and the wheels," Masson says. "That's completely counterintuitive because typically a noncovalent bond is much weaker than a covalent bond. It's a theoretical curiosity."

How this information might apply ultimately to in the future remains unknown, although many scientists envision that tiny vehicles like these could be used in electronics and data storage. Masson and Hla both stress that the work is still in its early stages. Before applications come along, scientists need to understand how molecules behave at the atomic scale.

"Our excitement is really about the fundamental science," Hla says. "This is just the beginning."

Explore further: Nanocar is the first step toward a controlled transport system at the molecular scale

Related Stories

Microscopic molecular cars to race in France

April 4, 2017

Microscopic molecular vehicles piloted by chemists and physicists will line up in the world's first nano-car race in France this month—but don't expect to see anything with the naked eye.

Rice scientists attach motor to single-molecule car

April 12, 2006

In follow-on work to last year's groundbreaking invention of the world's first single-molecule car, chemists at Rice University have produced the first motorized version of their tiny nanocar. The research is published in ...

Light drives single-molecule 3-wheelers

November 4, 2016

Scientists at Rice University and at the University of Graz, Austria, are driving three-wheeled, single-molecule "nanoroadsters" with light and, for the first time, seeing how they move.

Recommended for you

Breakthrough in ultra-fast data processing at nanoscale

October 20, 2017

A research team from the National University of Singapore has recently invented a novel "converter" that can harness the speed and small size of plasmons for high frequency data processing and transmission in nanoelectronics.

Art advancing science at the nanoscale

October 18, 2017

Like many other scientists, Don Ingber, M.D., Ph.D., the Founding Director of the Wyss Institute, is concerned that non-scientists have become skeptical and even fearful of his field at a time when technology can offer solutions ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.