Magnetic Bacteria Could Build 'Bio-Computers'
A species of bacteria that eats iron and turns it into magnetic particles could one day build your computer’s memory.
Researchers at the University of Leeds have capitalized on the natural ability of the bacterium, Magnetospirillum magneticum, to eat atom-sized bits of iron and turn those bits into tiny magnets that it then stores inside itself. The nanometer-sized magnetic parts are similar to those used in today’s hard drives. The finding could lead to bacteria producing electronic components to order.
"We are quickly reaching the limits of traditional electronic manufacturing as computer components get smaller. The machines we've traditionally used to build them are clumsy at such small scales. Nature has provided us with the perfect tool to circumvent this problem,” team leader Sarah Staniland, from the university's School of Physics and Astronomy, told the BBC.
Magnetospirillum bacteria ordinarily live in shallow pools of water, which often has various elements dissolved in it. Using a special protein, the bacteria draw iron from the water and build the tiny bits of magnetite, one of the most highly magnetic natural materials. They use the magnets to align with Earth's magnetic field and orient themselves, which in turn helps them find areas that have oxygen levels they prefer.
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The Leeds researchers took the iron-producing protein from the bacteria and applied it in a checkerboard pattern to a gold surface. They then immersed the protein-coated gold in a solution containing iron. When warmed up, the iron gathered on the protein in the same checkerboard pattern, essentially making many tiny magnets just as the bacteria do. That component could be the beginnings of a computer hard drive.
Hard drive technology hasn't changed much since the 1960s. A platter is covered with tiny metallic crystals that carry small magnetic fields whose orientation stores the bits (either 1 or 0) of data. To cram more information into them requires making those bits smaller, down to the current sizes of about 10 nanometers for each grain.
Of course, tiny hard drives are great, but a true nanoscale computer needs tiny wires as well. That's where some work by Staniland's longtime collaborator, Masayoshi Tanaka of the Tokyo University of Agriculture and Technology, comes in. In that case, the scientists built wires only 40 nanometers in diameter, which were coated in a different protein made from artificial cells. The principle is similar, but in this case the cells take in iron and extrude tiny quantum dots surrounded by a tube of protein.
Other scientists have shown that you can reduce the size of the magnetic domains of a drive down to atomic-scale sizes. And a University of Massachusetts team found that Geobacter sulfurreducens bacteria can make telectrically conductive filaments. Both Staniland and Tanaka plan to study the proteins in more detail to understand exactly how they work. That could lead to cheaper and more efficient methods for making nano-sized computers.