By manipulating a few genes inside these viruses, the team was able to coax the organisms to grow and self-assemble into a functional electronic device.

The goal of the work, led by MIT Professors Angela Belcher, Paula Hammond and Yet-Ming Chiang, is to create batteries that cram as much electrical energy into as small or lightweight a package as possible. The batteries they hope to build could range from the size of a grain of rice up to the size of existing hearing aid batteries.

Batteries consist of two opposite electrodes - an anode and cathode - separated by an electrolyte. In the current work, the MIT team used an intricate assembly process to create the anode.

Specifically, they manipulated the genes in a laboratory strain of a common virus, making the microbes collect exotic materials - cobalt oxide and gold. And because these viruses are negatively charged, they can be complexed between oppositely charged polymers to form thin, flexible sheets.

The result? A dense, virus-loaded film that serves as an anode.

A report on the work will appear in the April 7 issue of Science.

Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering; Chiang, the Kyocera Professor of Materials Science and Engineering (MSE); and Hammond, the Mark A. Hyman Professor of Chemical Engineering (ChE), led a team of five additional researchers.

They are MSE graduate students Ki Tae Nam (the lead author), Dong-Wan Kim, Chung-Yi Chiang and Nonglak Meethong, and ChE postdoctoral associate Pil. J. Yoo.

In their research, the MIT team altered the virus's genes so they make protein coats that collect molecules of cobalt oxide, plus gold. The viruses then align themselves on the polymer surface to form
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Contact: Elizabeth Thomson
thomson@mit.edu
617-258-5402
Massachusetts Institute of Technology
6-Apr-2006