Posted: January 10, 2008

Researchers discover road to sustainable electronic devices

(Nanowerk News) A recent discovery by a multinational team including a University of Minnesota scientist, professor Michael Sadowsky in the department of soil, water and climate, could lead to more environmentally friendly manufacturing of electronic devices.
Sadowsky and co-researchers found that the bacterium Shewanella has the unique ability to convert arsenate into arsenic sulfide nanotubes, tiny filaments that may find use in the optical, medical and electronics industries. The arsenic sulfide nanotubes are both electrically conductive and photoconductive. The findings were published in the Proceedings of the National Academy of Sciences journal in December, 2007.
When Shewanella, a type of bacterium found in soil and water, converts arsenate to arsenic sulfide, it leaves behind a yellow residue, which the researchers realized is a tangle of nanotubes. While the tubes don't conduct electrically at first, after eight days they become conductive as well as photoactive.
The scientists believe that this is the first time that these specialized arsenic-sulfide nanotubes have been produced by biological rather than chemical means. Nanotubes hold great promise, as they can be used to make fuel cells and batteries, biosensors for metals and other compounds in the environment and electronics industries, said Michael Sadowsky, a University of Minnesota professor in the department of soil, water and climate and one of the study’s authors. “The exciting thing is that these nanotubes produced by biological means may eventually allow us to produce novel semiconductor devices that could not be made other ways,” he said.
The research team, which is led by scientists from a South Korean university, expects to turn its attention next toward making the nanotubes smaller and more uniform, as well as looking for other unique properties. The study’s lead author, Hor-Gil Hur, is spending this academic year as a visiting scholar at the University of Minnesota.
Source: University of Minnesota
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