Analog DNA circuit does math in a test tube


Duke graduate student Tianqi Song and computer science professor John Reif have created strands of synthetic DNA that, when mixed together in a test tube in the right concentrations, form an analog circuit that can add, subtract and multiply as the molecules form and break bonds. While most DNA circuits are digital, their device performs calculations in an analog fashion, without requiring special circuitry to convert signals to zeroes and ones first. Credit: John Joyner
Often described as the blueprint of life, DNA contains the instructions for making every living thing from a human to a house fly.

By Robin A. Smith | PHYS.ORG

But in recent decades, some researchers have been putting the letters of the genetic code to a different use: making tiny nanoscale computers.

In a new study, a Duke University team led by professor John Reif created strands of synthetic DNA that, when mixed together in a test tube in the right concentrations, form an analog circuit that can add, subtract and multiply as they form and break bonds.

Rather than voltage, DNA use the concentrations of specific DNA strands as signals.

Other teams have designed DNA-based circuits that can solve problems ranging from calculating square roots to playing tic-tac-toe. But most DNA circuits are digital, where information is encoded as a sequence of zeroes and ones.

Instead, the new Duke device performs calculations in an analog fashion by measuring the varying concentrations of specific DNA molecules directly, without requiring special circuitry to convert them to zeroes and ones first.

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