World's Smallest Cars Have Moving Parts

Car-shaped molecules can zip around on a glass slide at about nine nanomiles per hour, and their wheels actually turn.

Understanding how these nanocars move could make it easier for researchers to build more sophisticated molecular machines.

"These are, of course, the world's smallest cars," says Jim Tour, a chemist at Rice University who has been making the cars for years. "We have considered (getting) nanoinsurance. I asked my friends at Motorola if they would make 6 x 1023 car phones for our mole of nanocars."

Initially, the vehicles' performance was perplexing. It was obvious that the cars could cruise around, but nobody could tell whether the individual parts were moving. They are way too small to see, even with the best equipment.

In a previous set of experiments, Tour's team was able to take pictures of the molecules with an electron microscope, but those experiments took place at a rather high temperature — 200 degrees centigrade — and the cars stuck to their golden road.

By putting the cars on a glass slide, and using a different instrument — a hacked fluorescence microscope — the team was able to see them moving around at room temperature, says Stephan Link, a chemist who led the study, published in the journal ACS Nano.

To verify that the carborane — carbon and boron — wheels actually turn, the researchers built some nano-tricycles and compared them to the cars. The triangles remained stationary, presumably because each of their wheels points in a different direction.

Link says that his team recorded some movies of the cars zipping around well before backing up their observations with some tedious measurements. He lamented that few people get excited about the hard data. Everyone wants to see the video clips.