...AND CHEAPER...:

The rod-shaped microbe, Geobacter sulfurreducens is, as its name implies, a member of the Geobacter genus, a group referred to as "electrigens" for their known ability to generate an electrical charge. It was UMass Amherst microbiologist Derek Lovley who found and wrote about the microbe in the late 80s.

It was also Lovlley's lab that discovered the microbe has a talent for producing electrically conductive protein nanowires, and his lab recently developed a new Geobacter strain that could produce them more rapidly and inexpensively. "We turned E. coli into a protein nanowire factory," Lovley says. What this means, he says, is that "With this new scalable process, protein nanowire supply will no longer be a bottleneck to developing these applications."

Enter electrical engineer Jun Yao, also of UMass Amherst. His specialty had been engineering electronic devices using silicon nanowires. The two decided to work together to see if they could turn Geobacter's protein nanowires into something useful.

The fruit of their collaboration is a device they call "Air-gen." It employs a thin film of Geobacter nanowires less than 10 microns thick resting on an electrode. Another, smaller electrode sits on top of the film. The film collects, or adsorbs, water vapor, and its surface chemistry and conductivity produce a charge that passes between the two electrodes through the fine gaps between individual nanowires.

Yao's doctoral student Xiaomeng Liu recalls, "I saw that when the nanowires were contacted with electrodes in a specific way the devices generated a current. I found that that exposure to atmospheric humidity was essential and that protein nanowires adsorbed water, producing a voltage gradient across the device."

Says Yao, "We are literally making electricity out of thin air." The Air-gen generates clean energy 24/7. "It's the most amazing and exciting application of protein nanowires yet." The two see their new technology as being non-polluting, renewable, and low cost- with distinct advantages over other developing energy sources such as solar and wind for at least one big reason, "it even works indoors" notes Lovley.

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