Virus-Built Micro Batteries for Miniature Applications

First, on a clear, rubbery material the team used a common technique called soft lithography to create a pattern of tiny posts either four or eight millionths of a meter in diameter. On top of these posts, they then deposited several layers of two polymers that together act as the solid electrolyte and battery separator.

Next came viruses that preferentially self-assemble atop the polymer layers on the posts, ultimately forming the anode. In 2006, Hammond, Belcher, Chiang and colleagues reported in Science how to do this. Specifically, they altered the virus's genes so it makes protein coats that collect molecules of cobalt oxide to form ultrathin wires -- together, the anode.

The final result: a stamp of tiny posts, each covered with layers of electrolyte and the cobalt oxide anode. "Then we turn the stamp over and transfer the electrolyte and anode to a platinum structure" that, together with lithium foil, is used for testing, Hammond said.

The team concludes in their PNAS paper: "the resulting electrode arrays exhibit full electrochemical functionality."

Source: medgadget.comAdded: 21 August 2008