When light is shone onto the motor, it spins uni-directionally. However, Tour found that, before the engine could spin, it would shoot excited electrons into the wheels, where the energy was dissipated as heat. ‘We had to switch the wheels to carborane structures instead,’ he explained. ‘There was then no energy transfer from the motor to the wheels, so they went round.’ The next step will be to prove that this wheel rotation can be translated into motion. ‘What we’ve done is analogous to building a car with a motor and putting it up on a block in a garage, revving it up and showing that it works,’ he said. ‘Now we have to get it out onto a track. We’ll initially try a gold surface again, but my suspicion is that we will get energy transfer to the surface so a non-conducting surface will be needed. We could use mica, which is insulating and a very smooth surface.’
The long-range goal is to use the nanocars to build structures from the bottom up. ‘We will initially be looking at small things like pieces of electronic memory chips, using the nanocar to move a nanoparticle into place,’ he said. Ultimately, they could be used to make much larger structures but that goal is some 50 years away.
The group is also now working on nanotrucks with a loading bay and self-assembling nanocars. Results from these projects should be published in the next few months.