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Proteins from Bacteria Generate Power for Wearables

Air-gen device

Measuring power from the Air-gen device (Lovley Lab, Univ. of Massachusetts – Amherst)

18 Feb. 2020. A collaboration of engineers and biologists created a way of producing electric power from humidity in the air with fine wires made of proteins from bacteria. A team from University of Massachusetts in Amherst describe their discovery in yesterday’s issue of the journal Nature (paid subscription required).

Researchers from the labs of electrical engineering professor Jun Yao and microbiologist Derek Lovley are seeking clean, renewable, portable, and low-cost methods for generating electric power, initially for small systems like wearable devices. Previous work by Lovley shows a bacterium known as Geobacter sulfurreducens has a number of unusual properties including the ability to ingest metallic substances, but also to produce a weak electric current. An early Science & Enterprise story in 2011 tells about Lovley’s work conducting an electric current through nanoscale wires made of fibrous proteins from Geobacter that work almost as well as fine metallic wires.

Yao’s lab studies nanoscale materials for circuits and electronic devices, including materials from biology. In this project, Yao, Lovley, and colleagues use proteins produced by Geobacter bacteria to generate, not just conduct, an electric current. To prove the concept, the researchers arrayed the fibrous protein nanowires in a film, with a thickness of about seven micrometers.

Proteins in the nanowires absorb and interact with changes in moisture to produce a sustained current, with electrodes connected to the film that capture the 0.5 volts it produces. The moisture is provided by humidity in the air. Tests of the device show the film generates a current even in dry conditions similar to a desert. Connecting several of the films in series scales up the voltage to a high enough level to power electronic devices.

“We are literally making electricity out of thin air,” says Yao in a university statement. Lovley adds, “It’s the most amazing and exciting application of protein nanowires yet.”

The UMass team calls the power system Air-gen and believes it can be used to power small systems, such as smart watches and personal medical devices. The researchers plan to produce a patch made of bacterial nanowires for powering wearable devices, which could eliminate the need for batteries, recharging, or even other renewable energy sources, such as solar or wind.

While Geobacter provides proteins able to prove the concept of humidity-based power sources, the microbe is not scalable for larger power needs or mass producing conductive protein nanowires. In more recent research, not yet published as of February 2020, Lovley and colleagues designed a benign synthetic strain of Escherichia coli or E. coli bacteria that more readily produces conductive proteins for nanowires similar to those produced by Geobacter. The authors believe these synthetic E. coli proteins could provide more opportunities for large-scale fabrication of conductive nanowires.

And Yao says large-scale systems are the ultimate goal. “For example,” notes Yao, “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. Once we get to an industrial scale for wire production, I fully expect that we can make large systems that will make a major contribution to sustainable energy production.”

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