DNA nanostructures could be used to build electronic circuits

Building molecular electronics with individual molecules using synthetic Deoxyribonucleic acid (DNA) origami nanostructures that self-assemble is the goal of researchers at the Missouri University of Science and Technology.

Self-assembling synthetic DNA origami nanostructures are one possible method to fabricate molecular metallic electrodes for electronics. With a single chemistry reaction, the scientists hope that many single-molecule electrode components could be made in parallel making the process scalable and cost-effective for a circuit. Molecules as electronic components could see billions of transistors integrated together, far more than today. Molecular electronics are expected to have lower computing costs, lower power dissipation (typically as heat) and higher efficiency. Making computer circuits this small will be impossible with today’s manufacturing technology.

The law stated by Intel co-founder Gordon Moore, known as Moore’s law, says that every 18 months the number of transistors double as they get smaller with the lithographic manufacturing process; doubling the computing power. But the miniaturisation of circuits is reaching the fundamental limits of the lithography process used to make them with silicon.

“One of the holdups today in making molecular electronics is that there’s not a definitive way to construct a metal electrode junction with nanometre gaps that can be reliably reproduced,” said Dr. Risheng Wang, an assistant professor of chemistry at the Missouri University of Science and Technology. Nanogap electrodes, where two electrodes are separated by a nanometre gap, are viewed as a fundamental building block for nanoscale electronics.

Rachel Nixon, a junior in chemistry and recipient of the new Carey and Christine Bottom Endowed Scholarship in Undergraduate Chemistry Research, and her mentor is Dr. Risheng Wang. Sam O'Keefe/Missouri S&T

Nanogap electrodes can be used in high density circuit designs, they can be made irrespective of the other components that would be connected to them and they allow molecular electronics to be integrated with more conventional scale electronics; which would serve as interfaces for their human users. Candidate molecules for this nanogap electrode are as small as five nanometres. Electronic circuits, so small they have individual molecules as components, are expected to enhance data transfer speeds, storage efficiency and signal processing.

A competing technology is carbon nanotube transistors. These have been created, but, according to Wang, no functional electrical circuits have been made so far. The self-assembling synthetic DNA process aims to overcome the manufacturing challenge of single-molecule electronics to create a metal electrode junction with nanometre gaps in a way that guarantees reliability during mass production.

DNA is deemed a good fabrication structure at the nanoscale because it can be programmed, giving it a predictability, it is stable and it is compatible with many other molecules. In Wang’s work self-assembling DNA nanostructures are expected to organise nanoparticles into pre-determined architectures, which is possible because of the self-assembly processes’ precision positioning and orientation at the nanometre scale. Wang’s work has been supported by a $350,000 grant from the United States government’s National Science Foundation’s division of computing and communications foundation. The funded work will continue until September 2021.

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