Magnet Making Bacteria Could Build Computers Say Scientists

Posted on May 7, 2012

Researchers at the University of Leeds, in collaboration with the Tokyo University of Agriculture and Technology, have used a type of bacterium which 'eats' iron to create a surface of magnets, similar to those found in traditional hard drives, and wiring. As the bacterium ingests the iron it creates tiny magnets within itself. The researchers hope to develop a new approach to building cheaper, more environmentally friendly electronics.

Dr. Sarah Staniland, the lead researchers on the team from the School of Physics and Astronomy at the University of Leeds, says, "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."

The magnetic array was created by Leeds PhD student Johanna Galloway using a protein which creates perfect nanocrystals of magnetite inside the bacterium Magnetospirilllum magneticum. In a process akin to potato-printing on a much smaller scale, this protein is attached to a gold surface in a checkerboard pattern and placed in a solution containing iron.

At a temperature of 80 degrees Celsius, similarly-sized crystals of magnetite form on the sections of the surface covered by the protein. The team are now working to reduce the size of these islands of magnets, in order to make arrays of single nanomagnets. They also plan to vary the magnetic materials that this protein can control. These next steps would allow each of these nanomagnets to hold one bit of information allowing the construction of better hard drives.

Galloway says, "Using today's 'top-down' method - essentially sculpting tiny magnets out of a big magnet - it is increasingly difficult to produce the small magnets of the same size and shape which are needed to store data. Using the method developed here at Leeds, the proteins do all the hard work; they gather the iron, create the most magnetic compound, and arrange it into regularly-sized cubes."

A different protein has been used to create tiny electrical wires by Dr Masayoshi Tanaka. These nanowires are made of 'quantum dots' - particles of copper indium sulphide and zinc sulphide which glow and conduct electricity - and are encased by fat molecules, or lipids. The magnetic bacteria contain a protein that moulds mini compartments for the nanomagnets to be formed in using the cell membrane lipids. Dr. Tanaka used a similar protein to make biological-based wiring - tubes of fat containing quantum dots. Dr. Tanaka says these biological wires could be grown connected to other components as part of an entirely biological computer.

The papers are published here and here in the journal Small.

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