An experimental working electrical wire made out of DNA, made by an Israeli-led team of scientists, could be a breakthrough toward building the next generation of computers.
Electrical circuits composed of molecules have long been the great hope for computer miniaturization. The main obstacle to their development has been finding the right wiring. DNA is a leading candidate, because it can self-assemble into complex shapes, which could make a tiny circuit. But nobody had been able to get DNA to actually conduct electricity — until now.
Building on years of research, the scientists managed to do so for the first time — transmitting a charge along the length of a special four-stranded DNA molecule they engineered. The scientists say the findings, published in the journal Nature Nanotechnology this week, could lead to the production of smaller, better, and cheaper computer chips, possibly in a few years.
“This research paves the way for implementing DNA-based programmable circuits for molecular electronics, which means that in the future we could have a new generation of computer circuits that can be more sophisticated, cheaper, and simpler to make,” said Prof. Danny Porath, the Etta and Paul Schankerman Professor in Molecular Biomedicine at the Hebrew University of Jerusalem, who led the study along with Prof. Alexander Kotlyar, a molecular biochemist at Tel Aviv University.
The study’s other authors came from institutions in Italy, Spain, Cyprus, Denmark, and the United States, including Columbia University.
The atomic option
Miniaturization is a measure of progress in computer engineering, and computers have steadily gotten smaller. A computer with the memory of an average laptop today was the size of a tennis court in the 1970s. Today’s computers can be stuffed into devices like smartphones and pacemakers.
Microelectronics deserves the credit for this progress, but for years, industry experts have warned that the field’s “top down” approach — which involves carving computer components from larger materials — cannot take computers much farther down the path of miniaturization. In particular, reducing the distance between transistors, the components that do the “thinking” for computers, has become increasingly difficult and expensive.
To continue making computers smaller, scientists are trying to get components to self-assemble from the “bottom up” — atom by atom. Since molecules are the smallest stable combinations of atoms, molecular electronics would be the ultimate realization of this aim. The problem is that since the 1990s, scientists have been stumped over how to use molecules as wiring.
For the past 15 years, Porath and Kotlyar have been looking for a solution. In last week’s study, they and their co-authors reported that they may have found one. The scientists showed that the four-stranded DNA can conduct up to more than 100 picoamperes of electricity up to more than 100 nanometers, 10 times further than had been managed under less rigorous conditions. Gideon Livshits, a doctoral student in Porath’s lab, developed an innovative experimental setup to measure the results in a replicable way in challenging conditions similar to those inside a computer.
Hopping across the divide
The results provide initial proof that a DNA-based molecule can serve as a wire. Although it has yet to be demonstrated, the scientists are confident that four-stranded DNA can be made to self-assemble in the same way as the double-helix type. They predict that within a few years, they will be able to produce molecular circuits with DNA wiring.
“We are the first to have transported current in a controllable manner in individual long molecules that can self-assemble,” said Porath. “We are continuing our research with the ultimate goal of implementing a programmable electrical circuit.”
Such a circuit would allow transistors and diodes, which can already be made of other types of molecules, to be packed more tightly together. As a result, the circuit would be faster and more efficient. Some expect that molecular circuits will also perform richer processing, more similar to the way the brain thinks than to the simple binary logic performed by silicon microprocessors.
To this end, the scientists are working to improve their DNA wire. Based on a theoretical model they tested in the study, they think electricity moves through the wire by hopping from segment to segment, and they hope to improve conductivity by enhancing this mechanism. They are also working to get the wire to self-assemble.