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February 02, 2011

Top down lithography and bottom up DNA origami combining for a path to next generation electronics

Using a concept called DNA origami, Arizona State University researchers are trying to pave the way to produce the next generations of electronics products. They integrate the 'bottom up' assembly of DNA origami with the 'top down' patterning of low cost lithography. The method, which involves sticking pieces of DNA to prepositioned gold islands, might help researchers in their bid to use DNA origami for nanoelectronics.

Nanoletters - Interconnecting Gold Islands with DNA Origami Nanotubes The research was covered late last year but there is some more information on the vision and goal.




Yu explains that he and Yan are exploring “how to use top-down lithography combined with modified bottom-up self-assembling nanostructures to guide the placement of nanostructures on silicon wafer surface.”

Top-down lithography is a process by which electrical circuit elements on a silicon wafer are constructed by cutting and etching, in a way similar to how sculptures are made. This is how today’s computer chips are manufactured.

Bottom-up self-assembly is a process in which molecules and/or nanoscale materials are self-assembled into desired structures using chemical bonds or various similar interactions.

Yu and Yan have discovered a way to use DNA to effectively combine top-down lithography with chemical bonding involving bottom-up self-assembly.

This involves a “DNA origami” design technique similar to the traditional Japanese art or technique of folding paper into decorative or representational forms. It allows DNA strands to be folded into something resembling a pegboard on which different molecules can be attached.

Enabling various molecules to attach to the DNA produces smaller nanostructure configurations – thus opening the way to construction of smaller electronic device components.

In the past it has proven difficult to combine top-down lithography with bottom-up self-assembly because the DNA nanostructures required to make it happen would bind indiscriminately to the silicon platform (called a substrate) – the material on which an electronic circuit is fabricated.

“There have been few successful demonstrations of how to put these bottom-up assembled nanostructures on the surface of the substrate where you want them to be,” Yu explains, “because you cannot just run these devices, you need to know where to connect what.”

To solve the problem, Yu’s research team prefabricated a gold “nano-island” at specific locations on a silicon substrate, then applied the DNA origami that has specific chemical ends that will bond only to the gold island and not the silicon wafer. This allows the DNA nanotubes to attach only to the islands.

The work demonstrates that it’s possible that a DNA double helix can be used to build one-dimensional and two-dimensional structures to enable the manufacture of smaller electronic memory devices – at a cost that would be far less than current manufacturing methods.

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