Researchers trying to make tiny machines have turned to the power of
nature, engineering a virus to attract metals and then using it to
build minute wires for microscopic batteries.

The resulting
nanowires can be used in minuscule lithium ion battery electrodes,
which in turn would be used to power very small machines, the
researchers report in Friday’s issue of the journal Science.

The
international team of researchers, led by a group at the Massachusetts
Institute of Technology, used the M13 virus, a simple and easily
manipulated virus.

"We use viruses to synthesize and assemble nanowires of cobalt oxide at room temperature," the researchers wrote.

They
modified the M13 virus’ genes so its outside layer, or coat, would bind
with certain metal ions. They incubated the virus in a cobalt chloride
solution so that cobalt oxide crystals mineralized uniformly along its
length.

They added a bit of gold for the desired electrical effects.

Viruses
cannot reproduce on their own but must be grown in cells — in this
case, bacteria. They inject their genetic material and then the cells
pump out copies of the virus.

The viruses formed orderly layers, the researchers reported.

The resulting nanowires worked as positive electrodes for battery electrodes, the researchers said.

They hope to build batteries that range from the size of a grain of rice up to the size of existing hearing-aid batteries.

Each
virus, and thus each wire, is only 6 nanometers — 6 billionths of a
meter — in diameter, and 880 nanometers long, the researchers said.

"We have previously used viruses to assemble semiconductor and magnetic nanowires," the researchers wrote.

reuters.com