2008-12-23 13:53:14
Nanovehicles could one day be used to build memory devices, buildings
Lucas Mearian
December 18, 2008 (Computerworld) The inventor of a car slightly wider than a strand of DNA took the top prize in nanotechnologies this week. James Tour, a professor of chemistry at Rice University, won the Foresight Institute Feynman Prize for experimental nanotechnology for his nanocar, which is four nanometers across and includes a chassis with an engine, a pivoting suspension and rotating axles attached to rolling buckyball wheels, each made of 60 carbon atoms.
Tour and his team of postgraduate and postdoctoral researchers not only built a car, but also constructed a nanotruck capable of carrying a payload. Asked why he did it, Tour's answer was simple: so that we can someday construct buildings and other large objects with molecular-size vehicles.
James Tour's nanocar in action
James Tour's nanocar in action
Click to view slide show of nanocar images
It took Tour and his team eight years to build the car. One of the significant challenges was attaching the wheels because the buckyballs had the adverse affect of shutting down the binding property -- the palladium reaction -- used to form the rest of the vehicle.
Over the next 30 years, Tour's nanotechnology could produce quantum-dot memory, which involves stringing together metal atoms in patterns that could then store data. Each quantum dot would consist of 50 metal atoms, he said.
Of course, that's a long way off, Tour acknowledged. He hasn't even patented the technology because by the time it could be used to make money, the patents would be expired. And we're not talking about a few nanotrucks carrying metal atoms to construct skyscrapers but 1023 or more vehicles, all carrying nanoparticles in orchestration, he said.
Until now, engineers have built things by taking larger objects and cutting them down to make smaller ones, Tour said. For example, trees are cut down to make tables, and as such, large silicon wafers are cut away to make transistors. But in the future, things will be built not from the top down, but the bottom up -- as in nature.
Tour pointed to hemoglobin as an example. Each heme group -- containing one iron atom -- carries only one molecule of oxygen, but billions of them go back and forth carrying oxygen from our lungs to the cells crying out for it. And on the way back out of the cells, the hemes detoxify by carrying out CO2. In the same way, nanovehicles could carry atoms to construct objects.
While self-assembling machines have been theorized for years, Tour argues that they can't succeed in creating complex structures, such as metals, because complex structures have many irregular segments to them.
"For example, nature builds by self-assembly but also by enzymatic assembly. Enzymes are natures nanomachines. They take molecules and stitch them together in nonperiodic patterns," Tour said. "That's what you need for complex assembly."
While enzymes don't work well outside of a biological host, if nano-size machines can be built that can pick up small objects like a molecule, bring them into place, attach them, and then go and pick up another one and put that in place, "then we can do exactly what enzymes do," he said.
There are three types of nanotechnology construction: passive, hybrid and active. Today, passive nanotechnology is being used with carbon nanotubes, which can greatly enhance the toughness of rubber, for example, or create pathways for bits of data.
Hybrids are nanostructures configured with another material. For example, Tour and his team have demonstrated the ability to combine carbon nanostructures made of graphite with silicon to create memory devices. It's the active nanotechnology, 15 years out or more, that will be useful in constructing large materials, Tour said.
So far, Tour's team has not only been able to build nanovehicles, but it has also been able to power them through two methods: heat and light. By heating the surface that the cars are on, the team is able to excite the molecules in the vehicle, and they move forward in a straight line until they hit an object. The light motion works on the principle of photo activation.
"We've made a motorized car, and for that, you shine light on it and the motor spins in one direction and pushes the car like a paddle wheel on the surface," Tour said. "Then we have other ones called nanoworms that wiggle back and forth as you shine light on them."