Researchers at Dublin City University lead an international project to study molecular computers that in time will be grown rather than built, writes Dick Ahlstrom
Smaller is faster in computer technology, but it has always been assumed that there are limits to miniaturisation. However, a Dublin research group hopes to break through these limits, shrinking computer components down to the level of molecules.
Prof Han Vos of Dublin City University leads a €2.5 million research project involving 11 other partners, including Prof Vincent Cunnane of the University of Limerick and scientists from the UK, the Netherlands, Finland, Denmark, Germany, Spain, Portugal and Switzerland. It involves learning how to build and test "nanoparticles", components measuring less than a billionth of a metre across.
The project is entitled Supramolecular Self-Assembly of Interfacial Nanostructures, or SUSANA for short. It received funding under the EU's Increasing Human Potential programme.
"In the end, molecular computing is really what we are doing," explains Prof Vos, professor of chemistry at the School of Chemical Sciences. He is also linked to the university's National Centre for Sensor Research and works on this project with Prof Robert Forster.
"We are trying to get a nanoparticle to talk to another nanoparticle through a molecule," Vos continues. "You want to try to use a single molecule as an on/off switch. That is easier said than done.
"The general trend in molecular computing is making faster and faster computers, but the components have to get smaller and smaller. We are coming to a limit. You can get smaller and smaller but it gets more expensive over time."
Traditional lithography techniques, used to make the smallest components known today, are now close to their theoretical limit. As a result, novel techniques must be developed to continue towards greater miniaturisation.
Being able to make nanoparticle switches would give an immediate benefit, he explains, because it would allow designers to produce smaller components. The smallest components today are about 50 billionths of a metre across.
"Molecular or nanoscale building-blocks are hundreds of times smaller than the smallest features that can conceivably be attained using present semiconductor technology," Vos says.
"Moreover, identical individual molecules and particles can be massively produced. Developments in this area depend on advances in chemistry, physics, biology, engineering and materials research and a multi- disciplinary approach will provide a fertile research ground for European researchers."
One of the main objectives of the project is to build switchable connectors, in which nanoparticles are linked to a metal contact or electrode or other nanoparticle through molecular bridges.
"In principle, we can make molecules that we can switch on and off several times," Vos says.
These devices must then be studied so that their properties are fully understood. This means finding ways to measure tiny currents passing through devices and learning how to switch them, either electrically or using light beams.
"Can we see electrons going through a couple of molecules?" is how Vos describes the challenge.
The great advantage of computing on this scale is that components aren't built; they are grown in chemical solutions. Both the nanoparticles and connecting molecules would be grown in batches in the lab.
"The advantage of a molecular switch is that you can make 100 billion at a time," Vos says.
THE team's initial approach involves taking an electrically conductive surface and then growing a layer of self-assembly molecules on this surface. Nanoparticles would then be attached to these molecules. The nanoparticle would be the part of the system holding the information, with the molecule serving as the transfer device relaying it.
"You have to connect [the nanoparticles] to other things. The molecules would be those connections," says Vos.
"We want to establish the concept. In the end we will come up with a concept that allows you to transfer information from one nanoparticle to another. We also want to develop a different nanoparticle based on a molecular precursor."
This would provide better control over the formation of the nanoparticles, allowing them to be made all the same shape and size.