Bacteria Fueling a Truly Green Revolution in Personal Electronics: UMass Amherst

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AMHERST, Mass. – Researchers at the University of Massachusetts Amherst recently announced that they have discovered how to engineer a biofilm that captures energy from evaporation and converts it into electricity. This biofilm, which was announced in Nature Communications, has the potential to revolutionize the world of wearable electronics, powering everything from personal medical sensors to personal electronics.

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Schematic view (r) and real photo (l) of a biofilm device. Credit: Liu et al., 10.1038/s41467-022-32105-6

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an integrated device
An integrated peripheral matrix powers a small LCD display. Credit: Liu et al., 10.1038/s41467-022-32105-6

“This is a very exciting technology,” says Xiaomeng Liu, a graduate student in electrical and computer engineering at UMass Amherst College of Engineering and lead author of the paper. “It is truly green energy, and unlike other so-called ‘green energy’ sources, its production is completely green.”

That’s because this biofilm – a thin sheet of bacterial cells the thickness of a sheet of paper – is produced naturally by a modified version of the bacterium Geobacter sulfurreducens. G. sulfurreducens is known to produce electricity and has previously been used in “microbial batteries” to power electrical devices. But such batteries require G. sulfurreducens to be properly cared for and fed with a constant diet. By contrast, this new biofilm, which can provide as much, if not more, energy than a comparably sized battery, is working, and working continuously, because it is dead. And because he’s dead, he doesn’t need to be fed.

“It’s much more efficient,” says Derek Lovley, professor emeritus of microbiology at UMass Amherst and one of the paper’s lead authors. “We have simplified the process of generating electricity by drastically reducing the amount of processing required. We sustainably grow the cells in a biofilm and then use this cell agglomeration. This reduces the energy input, simplifies everything and widens the potential applications.

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Geobacter nanowires
The tiny nanowires connecting colonies of G. sulfurreducens to each other.
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The secret of this new biofilm is that it produces energy from the moisture in your skin. Although we read stories about solar energy daily, at least 50% of the solar energy reaching the earth is used for water evaporation. “This is a huge untapped source of energy,” says Jun Yao, a UMass professor of electrical and computer engineering and the paper’s other lead author. Since the surface of our skin is constantly moist with sweat, the biofilm can “plug in” and convert the energy locked up in evaporation into enough energy to power small devices.

“The limiting factor in wearable electronics,” Yao explains, “has always been the power supply. Batteries run out and need to be replaced or charged. They are also bulky, heavy, and uncomfortable. thin and flexible which produces a continuous and regular power supply and which can be worn, like a bandage, like a patch applied directly to the skin, solves all these problems.

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biofilm on the neck
A biofilm-powered sensor on the neck that measures the mechanical signal of swallowing. Credit: Liu et al., 10.1038/s41467-022-32105-6

What makes this all work is that G. sulfurreducens grows in colonies that look like thin carpets, and each of the individual microbes connects to its neighbors through a series of natural nanowires. The team then harvests these mats and uses a laser to etch small circuits into the films. After the films are etched, they are sandwiched between the electrodes and finally sealed in a soft, sticky, breathable polymer that you can apply directly to your skin. Once this small battery is “plugged in” by applying it to your body, it can power small devices.

“Our next step is to increase the size of our films to power more sophisticated portable electronic devices,” Yao says, and Liu points out that one of the goals is to power entire electronic systems, rather than single devices.

This research was nurtured by UMass Amherst’s Institute for Applied Life Sciences (IALS), which combines deep, interdisciplinary expertise from 29 departments to translate basic research into innovations that benefit health and well-being. humans.

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