In the search for ways to store data permanently, ETH researchers have been inspired by fossils. (Illustration: Philipp Stössel/ETH Zurich)

Swiss researchers have hit upon a safe and efficient way to store large volumes of data in compact strands of 'fossilised' DNA. The sequencing code when retrieved and read was found to be error free. The information remains intact for millions of years unlike storage on microfilms which can last for a few hundred years or digital storage that uses much energy while requiring low temperatures.

Researchers led by Robert Grass, a lecturer at ETH Zurich's Department of Chemistry and Applied Biosciences, encapsulated the information-bearing segments of DNA in silica (glass) and used an algorithm to correct mistakes in the data.

The result is huge data like all the information on FB, Twitter and Wikipedia stored in a small heap of DNA that needs no particular care unlike vast arrays of servers that need to be maintained at cool temperatures! "In that tablespoon you would have everything very stable in a very small space with a guaranteed stability for a very long time," Grass told Reuters.

While the use of DNA as data storage medium was demonstrated two years ago, mistakes in writing and reading of DNA was a problem. This was despite the fact that the time period between feeding in the corresponding coding sequence of the DNA and the reading, or sequencing, of the data was very short. Over the long term, DNA can change significantly as it reacts chemically with the environment.

Much like the genetic code is held intact down millennia by being fossilized, the team wanted to fossilize the DNA. "Similar to these bones, we wanted to protect the information-bearing DNA with a synthetic 'fossil' shell," explains Grass.

That is why the team decided to encapsulate the DNA in silica spheres with a diameter of roughly 150 nanometres. They then tested the method by encoding Switzerland's Federal Charter of 1291 and The Methods of Mechanical Theorems by Archimedes in the DNA. To simulate the degradation of DNA over a long period of time, they stored it at a temperature of between 60 and 70 degrees Celsius for up to a month.

Compared to storing DNA on impregnated filter paper or in a biopolymer, the glass-engulfed DNA returned robust results. By using a fluoride solution, the DNA can be easily separated from the silica glass and the information read from it.

But storing is one aspect. Reading the data error-free was another task. While technological advancements in DNA sequencing has made the reading of stored data affordable, the process is not error-free. To overcome this, Reinhard Heckel from ETH Zurich's Communication Technology Laboratory developed a scheme where additional data is attached to the actual data. In case a set is lost, there is a back-up. This does make the information a bit more complex, but eventually error-free as shown in the test for Switzerland's Federal Charter and Archimedes' text.

If stored in low temperatures, such as that found in the Svalbard Global Seed Vault, where the temperature is minus 18 degrees Celsius, the glass-DNA can survive over a million years to tell the tale of a civilisation.