When You Come to a Split End, Take It

World smallest car cruises world's largest car parade.

+ More

It's easy to overlook almost any car in a lineup of more than 250 of the world's coolest rides. But in last Saturday's annual Houston Art Car Parade, Jim Tour's car was all but invisible. In fact, at the size of a single molecule, the Rice University chemistry professor's car is invisible, so he had to enter a scaled-up version a billion times bigger than the original and haul it in the back of a pickup truck.

As far as anyone knows, Tour's "nanocar" is the world's smallest car. Just how small is it? This car is so small a fleet of them could use a single strand of hair as a multilane highway. The entire car measures just 3-4 nanometers across, making it slightly wider than a strand of DNA. It consists of a single molecule just 1/20,000th the size of a human hair and includes a chassis with pivoting suspension and freely rotating axles. All this drives four rolling buckyball wheels—spheres of pure carbon containing 60 atoms apiece.

The nanocar was Tour's first entry in the Art Car Parade, which has been organized for the past 20 years by Houston's Orange Show Center for Visionary Art. What started as a 40-car show case with 2,000 onlookers has become a legendary event that attracts more than 250 vehicles and other entries from 23 states and Canada, a live audience of some 200,000 and a television audience of 225,000. Parade entries include anything on wheels from unicycles to lawnmowers to cars, and are as likely to be made by amateurs as by recognized artists.

Tour's entry is actually an experiment in building molecule-size machines that really work. "The synthesis and testing of nanocars and other molecular machines is providing critical insight in our investigations of bottom-up molecular manufacturing," he said. "We'd eventually like to move objects and do work in a controlled fashion on the molecular scale, and these vehicles are great test beds for that. They're helping us learn the ground rules."

Tour and his research group spent almost 8 years perfecting the techniques used to make the car. A key problem was finding a way to attach the buckyball wheels without destroying the rest of the car. Buckyballs had a tendency to shut down the palladium reactions used in the formation of the axle and chassis.

The group has also developed a "motorized" nanocar powered by light and a nanotruck capable of carrying a payload. The research was funded by the Welch Foundation, Zyvex Corporation and the National Science Foundation.

—By Leslie Fink/NSF

This report is provided by the National Science Foundation, an independent federal agency that supports fundamental research and education across all fields of science and engineering, in partnership with U.S. News and World Report.