A Farewell to Chips: Tiny DNA Diode Raises Bets on Silicon-Free Future

Scientists at Ben-Gurion University and the University of Georgia have used a single DNA molecule to make the world's smallest diode, a method which could provide an alternative to silicon chips.

Researchers in Israel and the US have used a single molecule of DNA to create the smallest ever, single-molecule diode, a significant milestone in the development of molecular electronic devices which could form an element of future nanoscale circuits. 

A diode is a semiconducting electrical component, which allows current to flow in one direction but prevents its flow in the other direction.

The scientists took a single DNA molecule constructed from 11 base pairs and connected it to an electronic circuit only a few nanometers (a few billionths of a meter) in size.

After they inserted layers of a molecule called "coralyne," between the layers of DNA, the current flowing through the DNA was 15 times stronger for negative voltages than for positive voltages, the necessary feature of a diode.

Illustration of the coralyne-intercalated DNA junction used to create a single-molecule diode, which can be used as an active element in future nanoscale circuits

© Photo : U. Georgia/Ben-Gurion U.

"In summary, we have constructed a molecular rectifier by intercalating specific, small molecules into designed DNA strands," said Professor Bingqian Xu, one of the authors of a paper published in Nature Chemistry on Monday. 

"Our discovery can lead to progress in the design and construction of nanoscale electronic elements that are at least 1,000 times smaller than current components," he explained.

Xu said that the predictability, diversity and programmability of DNA makes it a leading candidate in the replacement of silicon-based chips, as scientists are pushing the physical limits of silicon by placing more and more computing power onto smaller and smaller chips.

"If silicon-based chips become much smaller, their performance will become unstable and unpredictable," he said. 

A prediction made by Intel co-founder Gordon Moore in 1965, known as Moore's Law, stated that the number of transistors in a dense integrated circuit would double approximately every two years; so far this has more or less held true.

Although the pace slowed last year according to Intel, the possibility of using DNA for the design of functional electronic devices using single molecules offers hope that advances in computer processing will continue.