Researchers at Empa and their Dutch co-workers have developed the smallest electrical car in the world. The 4-wheel drive vehicle is noiseless and does not produce any harmful gases or pollutants as it travels on a copper surface on four wheels driven by electricity. It measures approximately 4 by 2 nanometers and consists of one molecule.
Background of the Vehicle
Typically, engines are used to transform electrical, thermal and chemical energy into kinetic energy. Nature uses motor proteins, such as actin in muscles and kinesin, in cells to perform the same motion. These proteins move alongside other similar proteins, much like trains do on a track. In the process, the proteins burn adenosine triphosphate, or ATP, which is a type of chemical fuel needed to make the motions happen.
Chemists are using the same concepts to design small molecular transport devices and machines that will carry out tasks on a much smaller scale. Researchers have successfully developed a way to synthesize a molecule from four wheels that have the ability to travel straight ahead. The car does not require the use of gasoline fuel or rails; it moves simply by using electricity. Researchers also boast that the smallest car in the world even has 4-wheel drive.
How Does the Car Work?
Developers placed the car on top of a copper surface, put an STM tip over top of it and left a small gap. They then applied a 500 mV voltage so that electrons could be transported through the molecule and start structural changes within the four motor units, or wheels. The rearrangement is not favorable in terms of room as bigger side groups fight to maintain their space. Because of this, the two side groups fight against each other to get past and use their energy until they reach a better position. In doing so, the side groups force the wheel to spin a half rotation. Thus, if all four wheels are spinning at the same time, the vehicle moves forward.
Is There Room for Improvement?
The car, measuring 4 by 2 nanometers is roughly one billion times smaller than Volkswagen’s Golf vehicle. While it does travel without traditional gasoline, it requires refueling of electricity after the wheels spin a half revolution. Researchers have not yet found a way to add an additional gear; the wheels can only move in one direction.
The developers also noticed that the car can land on the copper in two different ways: in the correct one, all four wheels theoretically turn the same direction, and in the incorrect way, the back wheels move forward but the front ones move backward, thus letting the car stand still.