Researchers at the University of Massachusetts Amherst have engineered a biofilm that harvests the energy in evaporation and converts it to electricity. This biofilm has the potential to revolutionize the world of wearable electronics, powering everything from personal medical sensors to personal electronics.
The 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. The bacteria is known to produce electricity and has been used previously in “microbial batteries” to power electrical devices. But such batteries require that G. sulfurreducens is properly cared for and fed a constant diet. By 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.
The team has simplified the process of generating electricity by radically cutting back on the amount of processing needed. They 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 secret behind this new biofilm is that it makes energy from the moisture on your skin. 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.
The team’s next step is to increase the size of the films to power more sophisticated skin-wearable electronics.