Long-Term Data Storage—In Glowing Dyes

seven vials of fluorescent dyes

Researchers at Harvard University and Northwestern University, USA, have demonstrated a system that encodes data in mixtures of seven fluorescent dyes—and that can reportedly read, store and write such data at rates far faster than previously demonstrated molecular-storage techniques. [Image: American Chemical Society video screenshot]

Hard-disk drives, flash drives and other devices currently used to store digital information all suffer from a major shortcoming: a very limited operational lifetime, commonly only twenty years or less. That has left researchers searching for alternative materials and strategies that remain stable for much longer periods.

One potential approach is molecule-based data storage, which can, in principle, remain stable for thousands of years without consuming energy. Now, a team of scientists at Harvard University and Northwestern University, USA, has developed a new method that uses mixtures of fluorescent dye molecules deposited on an epoxy surface with an inkjet printer (ACS Cent. Sci., doi: 10.1021/acscentsci.1c00728). According to the researchers, their optochemical molecular information storage system has the fastest reported read rate for any molecule-based storage method.

The trouble with molecules

Preserving information with molecules has certain advantages over traditional data storage devices, such as extremely long-term stability, high areal density and the ability to operate without power. However, the disadvantages—in particular, slow read/write speeds coupled with high costs—have proved significant enough to hinder any widespread, real-world applications.

For example, synthetic DNA inspired by nature is one of the densest methods of data storage. But trying to decode even a simple message can take several hours even with modern-day DNA sequencing techniques, making the approach impractical.

Previously, the researchers behind the current work had demonstrated information storage in a set of oligopeptides distinguishable by molecular weight using a mass spectrometer. Unfortunately, mass spectrometry destroyed the information during readout—and, again, the process remained slow, at a rate of 20 bits per second.

A promising first step

In the new work, the team decided to tackle the problem from a different angle, replacing oligopeptides with optically distinguishable molecules that could be written once but read many times. The group employed inkjet printing to deposit tiny droplets of seven commercially available fluorescent dyes on a thin film of epoxy polymer. A reaction between the substrate and dyes caused them to become covalently immobilized, and stable to more than 1,000 reads without a noticeable loss of intensity.

Readout occurred by imaging the printed substrate using a microscope equipped with a multichannel fluorescence detector, which could simultaneously and independently detect the presence or absence of dye molecules at a specific location. With the adoption of such features, the optochemical molecular information storage system recorded what the team says is the fastest reading speed of any molecular information storage method yet, at 469 bits per second.

In total, the researchers wrote, stored and read a total of 400 kilobits of text and images with greater than 99% recovery of information. Of course, much more work is needed to determine the method’s true applicability, but the researchers view these initial results as promising in terms of stability, speed and cost.

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