In October 2005, a team of scientists from Rice University in Texas successfully tested the first nano automobile. Although this was not the first attempt to create a nanostructure that resembles in some sense an actual car, it was the first to actually move with some degree of control.
The original nanocar had a chassis, 2 axles, and four wheels made of buckyballs, a single molecule consisting of C60, i.e., 60 carbon atoms, arranged in a spherical shape similar to a soccer ball. The car measured just 3-4 nanometers, making it a tad wider than a DNA strand and about 20,000 times smaller than the width of a strand of a human hair. Movement on four wheels in a direction perpendicular to its axles distinguishes the nanocar from other similarly-shaped nanostructures built to date. To verify that the nanocar was in fact rolling rather than merely slipping or sliding, the scientists built it on a gold platform, which they heated to 200 degrees C, and then analyzed complex measurements of a series of images captured by scanning tunneling microscope (STM), capable of detecting single atoms.
Interview with Professor Kevin F. Kelly
The improved nanocar has a boron chassis and wheels, and includes a light-sensitive “motor” that propels the car forward as shown in the following flash presentation.
Since the introduction of the first nanocar, the Rice team has strived to create more useful utilizations for their invention. TFOT interviewed Professor Kevin F. Kelly, one of the researchers working on the nanocar project at Rice, and asked him about some of the future applications of the technology.
Q: Have you improved upon the original design of the nanocar in the past year and have you created other nanodevices?
A: Since last fall, we have test driven nanocars with a second type of molecular wheel, but it appears that buckyballs still make the best nanotires. We are also investigating other prototype molecular structures, synthesized by Professor Tour’s group, for the chassis. We are particularly interested in ones that will undergo achemical reaction and carry a second molecule as cargo. These have been nicknamed “nanotrucks.”
Q: Do you see short-term practical applications coming out of your nanocar work?A: As our understanding of molecular motion on surfaces increases, I believe we will be able to use this knowledge to design more efficient catalytic systems, e.g., the catalytic converter in your automobile. Catalytic reactions on a large-scale are essential in the petrochemical industry so it behooves us to make these as efficient as possible.
A: I think it would be reasonable to expect applicable benefits from these molecules on a longer time scale, more like fifteen or twenty years. In addition to the chemical benefits, molecular structures like these might see use as a molecule-based electromechanical memory for computers.
Shortly following our interview with Dr. Kelly, new details on the second generation nanocar were revealed. TFOT asked Yasuhiro Shirai, a graduate student in chemistry from Professor James Tour‘s Laboratory at Rice, to explain some of the differences between the original (2005) nanocar and the new work conducted by the team in 2006.
Shirai: The main difference between the nanocar (published in the 2005 paper) and the motorized nanocar (published in the 2006 paper) is that the nanocar has C60 wheels, a chassis, and axles, whereas the 2006 motorized nanocar has carborane (boron cluster) wheels, a chassis, axles, and a motor. The motor can rotate with 365 nm light, and in the 2006 paper we demonstrated rotation of the motor in solution-phase testing.
In the 2006 work, we also proved that the original C60 wheel cannot be used for the motorized nanocar because it quenches the motor rotation. This is the reason we replaced the original C60 wheels with carborane wheels.
In the 2005 paper, we were able to demonstrate a rolling motion of the nanocar using thermal energy (by heating the gold surface). The motion was imaged by STM. In the 2006 work, we described synthesis of the molecule and rotation of the motor in solution using a beam of 365 nm light. Now we are trying to image self-propelled motion of the motorized nanocar on a surface when it is irradiated with 365 nm light.