Protein Nanowires
© UMASS AMHERST/YAO AND LOVLEY LABS
Graphic image of a thin film of protein nanowires generating electricity from atmospheric humidity.
Scientists in the US have developed a device they say uses a natural protein to create electricity from moisture in the air.

Writing in the journal Nature, electrical engineer Jun Yao and microbiologist Derek Lovley, from the University of Massachusetts Amherst, introduce the Air-gen (or air-powered generator), which Lovley describes as "the most amazing and exciting application of protein nanowires yet".

Air-Gen has electrically conductive protein nanowires produced by the microbe Geobacter, which Lovley discovered in the Potomac River three decades ago and has been working with ever since, in particular investigating its potential for "green electronics".

The Air-gen connects electrodes to the protein nanowires in such a way that electrical current is generated from the water vapour naturally present in the atmosphere.

It requires only a thin film of protein nanowires less than 10 microns thick. The bottom of the film rests on an electrode, while a smaller electrode that covers only part of the nanowire film sits on top.

The film adsorbs water vapour from the atmosphere. A combination of the electrical conductivity and surface chemistry of the protein nanowires, coupled with the fine pores between the nanowires within the film, establishes the conditions that generate an electrical current between the two electrodes.

Developed in Yao's lab, Air-gen is low-cost, non-polluting and renewable, and needs neither sun nor wind, the researchers say. It can work indoors, or in extremely low humidity of the desert.

The current generation can power only small electronics, but they hope to bring it to commercial scale soon. Beyond that is the idea a small Air-gen "patch" that can power electronic wearables such as health and fitness monitors and smart watches. And then, maybe, there are mobile phones.

"The ultimate goal is to make large-scale systems," says Yao. "For example, the technology might be incorporated into wall paint that could help power your home. Or, we may develop stand-alone air-powered generators that supply electricity off the grid."

Lovley also is working to improve the practical biological capabilities of Geobacter. His lab recently developed a new microbial strain to more rapidly and inexpensively mass produce protein nanowires.

"We turned E. coli into a protein nanowire factory," he says. "With this new scalable process, protein nanowire supply will no longer be a bottleneck to developing these applications."