The bacteria powering a truly green revolution in personal electronics

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AMHERST, MA — Researchers at the University of Massachusetts Amherst recently announced that they figured out how to develop a biofilm that uses the energy of evaporation and converts it into electricity. This biofilm that was announced in nature communication, has the potential to revolutionize the world of wearable electronics, powering everything from personal medical sensors to personal electronics.

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

That’s because this biofilm — a thin layer of bacterial cells about the thickness of a sheet of paper — is naturally produced by an engineered version of the bacteria Geobacter sulfurreducens. G. sulphurreducens is known to generate electricity and was previously used in “microbial batteries” to power electrical devices. But such batteries require that G. sulphurreducens properly cared for and regularly fed. In contrast, this new biofilm, which can provide as much, if not more, energy than a comparable-sized battery, works continuously because it’s dead. And because it’s dead, it doesn’t need to be fed.

“It’s much more efficient,” says Derek Lovley, Distinguished Professor of Microbiology at UMass Amherst and one of the lead authors of the paper. “We’ve simplified the process of power generation by radically reducing the amount of processing required. We grow the cells sustainably in a biofilm and then use this collection of cells. This reduces the energy consumption, makes everything easier and expands the possible applications.”

The secret behind this new biofilm is that it derives energy from the moisture on your skin. Although we read stories about solar energy every day, at least 50 percent of the sun’s energy that reaches the earth goes to the evaporation of water. “This is a huge untapped source of energy,” says Jun Yao, professor of electrical and computer engineering at UMass and the paper’s other senior author. Because the surface of our skin is constantly damp with sweat, the biofilm can “take in” and convert the energy trapped in evaporation into enough energy to power small devices.

“The limiting factor in wearable electronics,” says Yao, “has always been the power supply. Batteries are dead and need to be changed or charged. They’re also bulky, heavy and uncomfortable.” But a clear, small, thin, flexible biofilm that generates a continuous and steady power supply that can be applied directly to the skin like a band-aid solves all of these problems.

What all this works is that G. sulphurreducens grows in colonies that look like thin mats, and each individual microbe is connected to its neighbors by a series of natural nanowires. The team then harvests these mats and uses a laser to etch small circuits into the foils. Once the foils are etched, they are placed between electrodes and finally sealed in a soft, sticky, breathable polymer that you can apply directly to your skin. Once this tiny battery is “plugged in” by attaching it to your body, it can power small devices.

“Our next step is to scale up our films to power more sophisticated skin-wearable electronics,” Yao says, and Liu points out that one of the goals is to power entire electronic systems rather than individual devices take care of.

– This press release was originally published on University of Massachusetts Amherst website

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