Technology

Logical Circuits Created With Slime Molds

March 28, 2014 | by Lisa Winter

Photo credit: Adamatzy and Schubert

What is your current computer made of? Aluminum? Silicon? Plastic? Perhaps the slime mold Physarum polycephalum? If that last one isn’t true for you now, there’s a chance it will be in the future. Andrew Adamatzky from the University of the West of England and Theresa Schubert of Bauhaus-University Weimar have published a paper in the journal Materials Today which describes how they were able to use the slime mold to create a logical circuit.

Previous research has shown that slime molds are actually able to solve mazes, but they might even be more remarkable than that. Last year, Adamatzky and Schubert were able to determine that P. polycephalum demonstrates characteristics of a memristor. A memristor (portmanteau of “memory” and “resistor”) is a theoretical circuit that not only converts electrical signals into 1 and 0 to carry out calculations, but it is even able to remember the last thing it was doing when the signal ended. While many are getting close to manufacturing a memristor, thermodynamics pose considerable obstacles.

Traditionally, P. polycephalum grows in its environment by spreading out and taking up nutrients through its extensive network of nanotubes. The researchers were able to exploit the process by feeding mold oat flakes, which encouraged growth, and salt, which inhibited it. This ensured that the tubes would be arranged in the desired configuration. The researchers then fed the mold dyes that contained magnetic nanoparticles and fluorescent beads. When a current was administered to the mold, the particles were transported through the tubes. 

These nanotubes could be developed into the first biological “lab on a chip” that is able to process small samples to be used as a diagnostic tool. If they can be adapted into a larger network, the slime mold circuit could perform the same Boolean logic circuit operations that are currently used by computers to perform tasks. There are seven basic logic gates: AND, OR, NOT, XOR, NOR, XNOR, and NAND. The slime molds were shown to be capable of using XOR and NOR gates. Adding additional logic gates into the network could allow the slime mold to perform computations using binary.

Of course, we’re a long way off from actually having a computer made out of slime mold, you know, with it being a living thing and all. However, these organisms are incredibly talented at finding the most efficient pathways and are relatively cheap and easy to work with. While you probably won’t be camping outside to get the latest iSlime laptop, the editor of Materials Today, Steward Bland, has stated that “research such as this is helping to push and blur the boundaries of materials science, computer science and biology, and represents an exciting prospect for the future.”

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