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A liquid hard drive containing a suspension of nanoparticles could be used to store impressive amounts of data: 1 terabyte per tablespoon.

Researchers from the University of Michigan and New York University have been simulating wet information storage techniques which uses clusters of nanoparticles suspended in liquid. These clusters of particles can store more data than conventional computer bits which have just two storage states: 0 and 1. The clusters of particles work a bit like Rubik's Cubes to reconfigure in different ways to represent different storage states. A 12-particle memory cluster connected to a central sphere can have almost eight million unique states, which is equivalent to 2.86 bytes of data.


The system works by having nanoparticles attached to a central sphere. When the sphere is small, the outer particles trap each other into place, storing data. If the sphere is a bit larger, the particles can be reconfigured to store different information. The team created a cluster involving four particles on a central sphere -- all made of polymers. By heating the liquid up, the spheres expand and the particles can rearrange themselves in predictable ways. Although the four-particle clusters have only two distinguishable configurations (i.e. like a regular bit), the plan is create clusters with many more particles.

The simulations showed that a tablespoon of a solution containing a three percent concentration of 12-nanoparticle clusters could store a terabyte of data. This compares with the smartphone-sized device required to store this amount of data as an external hard drive.

Post-doctoral researcher Carolyn Phillips described the clusters as like Rubik's Cubes. "You can use the same mathematics that describes a Rubik's Cube to show that every rearrangement of the cluster's spheres is possible and reachable."

For liquid hard drives to become a practical reality, the team needs to work out a way to lock the clusters into the right shapes across a large volume of liquid and then read the data back with ease -- currently the team is counting bits with a scanning tunnelling microscope.


These sorts of clusters could be used to detect pollutants in water or allow medical information processing to take place inside the body. Memory clusters could also allow for sensing and control in soft robots.

Before then, it's more likely that the clusters could be used as unique identifiers for liquid materials, allowing for the tracking of controlled substances such as fuel, explosives and chemicals used to make illegal drugs.

You can read the full paper for free here, but you may have to register to view it.