Researchers at the University of Massachusetts Amherst recently announced that they have figured out how to engineer a biofilm that harvests the energy in evaporation and converts it to electricity.

a A harvested biofilm sheet of G. sulfurreducens strain CL-1 (schematic inset), floating on water. Scale bar, 2 cm. b Schematic of using laser-patterned biofilms to construct (i) single device and (ii) interconnected device array on a PDMS substrate (gray), with a portion of the biofilm at one electrode immersed in water. Image Credit: UMass Amherst. Click the study paper link to Nature Communications for more images and information.

This biofilm has the potential to revolutionize the world of wearable electronics, powering everything from personal medical sensors to personal electronics.

The development has been announced in Nature Communications.

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

That’s because this biofilm – a thin sheet of bacterial cells about the thickness of a sheet of paper – is produced naturally by an engineered version of the bacteria Geobacter sulfurreducens. G. sulfurreducens is known to produce electricity and has been used previously in “microbial batteries” to power electrical devices. Such batteries require that G. sulfurreducens is properly cared for and fed a constant diet.

In contrast, this new biofilm, which can supply as much, if not more, energy than a comparably sized battery, works, and works continuously, because it is dead. And because it’s dead, it doesn’t need to be fed.

Derek Lovley, Distinguished Professor of Microbiology at UMass Amherst and one of the paper’s senior authors explained, “It’s much more efficient. We’ve simplified the process of generating electricity by radically cutting back on the amount of processing needed. We sustainably grow the cells in a biofilm, and then use that agglomeration of cells. This cuts the energy inputs, makes everything simpler and widens the potential applications.”

The science behind this new biofilm is that it makes energy from the moisture on your skin. Though we daily read stories about solar power, at least 50% of the solar energy reaching the earth goes toward evaporating water.

“This is a huge, untapped source of energy,” said Jun Yao, professor of electrical and computer engineering at UMass, and the paper’s other senior author. Since the surface of our skin is constantly moist with sweat, the biofilm can “plug-in” and convert the energy locked in evaporation into enough energy to power small devices.

“The limiting factor of wearable electronics,” said Yao, “has always been the power supply. Batteries run down and have to be changed or charged. They are also bulky, heavy, and uncomfortable.” But a clear, small, thin flexible biofilm that produces a continuous and steady supply of electricity and which can be worn, like a Band-Aid, as a patch applied directly to the skin, solves all these problems.

What makes this all work is that G. sulfurreducens grows in colonies that look like thin mats, 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. Once the films are etched, they’re sandwiched 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 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 skin-wearable electronics,” said Yao, and Liu pointed out that one of the goals is to power entire electronic systems, rather than single devices.

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


This is in the “amazing news” zone and quite justified. The Massachusetts Amherst team certainly hit a major home run with this development effort. While the grid load isn’t a major issue, there are millions of little batteries getting replaced and trashed regularly and that is getting to be more of a problem than is on the problem radar for now.

For now the technology is lab sample and more development is underway. Then the actual lifespan isn’t known, nor the scalability or projected costs. Its not a sure thing, yet.

Everyone is perspiring a wee bit almost everywhere essentially all the time. There is great potential in this technology. As more electronics become more mirco and power demands creep down more devices will make it to this technology’s power output level.

The big question that remains, are we willing to have a sticky Band-Aid kind of thing glued to us most of the time?


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