Page last updated at 10:57 GMT, Monday, 17 August 2009 11:57 UK

DNA 'organises itself' on silicon

DNA on silicon (IBM)
Triangular "DNA origami" were made to assemble on etched carbon and silicon

Shapes of DNA have been used to enhance the production of circuits for next-generation computer chips.

Researchers reporting in Nature Nanotechnology have now shown how to get engineered "DNA origami" to self-organise on silicon.

The origami can be designed to serve as a scaffold for electronic components just six billionths of a metre apart.

Making chips with components closer together leads to smaller devices and faster computers.

The six nanometre mark is nearly eight times better than the current industry produces.

Several research groups have shown that DNA itself can be used to store or manipulate data, and the juggling of DNA in a test tube or within bacteria has been shown to solve simple computational tasks.

The current method, by contrast, leverages the ability to design DNA strands into regular shapes such as triangles.


The computer industry would like to make use of next-generation materials with favourable electronic properties such as carbon nanotubes or nanowires.

Such structures are tiny and difficult to manipulate, but the chemical groups hanging off of DNA molecules could be used as anchor points for them.

Those anchor points can be as little as six nanometres (nm) apart, making these DNA-bound circuit components smaller and thus faster than can currently be produced.

The current industry standard for etching electronic components from larger structures - a so-called "top down" approach - has components at a distance of 45nm.

DNA molecular structure (SPL)
DNA offers many anchor points for tiny circuit components

But the new "bottom-up" technique promises distances nearly four times better than the planned industry move to 22nm.

What makes the technique particularly useful is that the regular shapes of the circuit-loaded DNA origami allows them to fit neatly into shaped pits the researchers bored into silicon or carbon using standard techniques.

This self-assembly occurs when a liquid filled with the origami is put in contact with the etched surfaces in what the authors call a case of "bottom-up keys" fitting into "top-down locks".

Because the eventual placement of the components puts them so much closer, the approach could lead to computers that are both smaller and faster.

However, the motivations are also economic - industry-wide shifts to smaller components are phenomenally expensive to the manufacturers.

"The combination of this directed self-assembly with today's fabrication technology eventually could lead to substantial savings in the most expensive and challenging part of the chip-making process," said Spike Narayan, a science and technology manager at IBM's Almaden research centre.

Fuller integration of the technique could take as much as 10 years, IBM said.

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