What the World’s Tiniest ‘Monster Truck’ Reveals

“We incorporated positive charge receptors in the car,” Hla says. “So if we injected a positive charge 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 molecular machines 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.”