Yes, “zombie bacteria” is a real thing; it’s a phrase that was coined over a decade ago to label technically dead microbial bacteria that feeds on organic compounds. For the world of wearables, what these proteobacteria consume is less compelling than what they produce: electricity. And human sweat may be the perfect meal for these little zombies to power smartwatches, patches, and devices of all kinds. While we’re not there yet, researchers at the University of Massachusetts Amherst have created a microbial biofilm that contains zombie bacteria — officially called Geobacter sulfurreducens, or G. sulfurreducens — which can generate an electrical current with just water.
So how do we get live electricity from dead microbes? Proteins. While not alive, the bacterial cells still contain proteins that help prompt the movement of electrons that the biofilm collects from water, including sweat and moisture in the air. The proteins also help the bacteria engage in behavior that feels right out of a sci-fi monster flick — our little undead microbes sprout tendrils that direct energy away from the bacteria. Dubbed conductive nanowires, these tendrils allow the flow of currents from the bacteria to another source, such as a metal receptor or other types of microbes. Researchers grew colonies of these G. sulfurreducens and encased them in an ultra-thin biofilm.
The flexible microbial biofilm can be placed between two mesh electrodes and integrated into a variety of devices that are powered by its current. According to researchers, these devices include patches that can create electricity on the skin to provide continuous power to wearables. They say that the electricity generated is comparable to that of biofilms that employ microbial fuel cells, similar bacteria-based technology that uses chemical energy to generate electricity. But usually these bacteria need to be alive and so the zombie twist here is novel. However, the idea of generating electricity from bacteria is not new — it has been around for over 100 years.
And just as zombies nearly ended all human pollution in The Walking Dead, the energy source is about as green as you get. While researchers allow that the materials used to create the biofilm were not sustainably produced, evaporation-based generation of electricity through bacteria creates no toxic waste and is an environmentally friendly energy source almost without compare.
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