Wear your smartwatch, or smart band without charging, using a new innovation where devices can charge themselves using human sweat

Your perspiration generates long-term, continuous power thanks to microbial biofilm

Wear your smartwatch, or smart band without charging, using a new innovation where devices can charge themselves using human sweat

A microbial biofilm has been proven as a cohesive, flexible material that absorbs evaporation energy and converts it to electricity by researchers at the University of Massachusetts Amherst. This biofilm has the potential to change the face of wearable electronics by powering everything from personal medical sensors to personal gadgets.

The biofilm is a thin layer of bacterial cells the thickness of a sheet of paper. It is made naturally by a genetically modified strain of the bacterium Geobacter sulfurreducens. This microorganism is known to create energy and has previously been used to power electrical equipment in "microbial batteries." However, such batteries need the right care and feeding of G. sulfurreducens. In contrast, because it is dead, the new biofilm, which can give as much energy as a comparable sized battery, functions continually. It also doesn't need to be fed because it's dead.

The G. sulfurreducens develop in colonies that resemble thin mats, and each individual bacterium communicates with its neighbors via a network of what the researchers describe "natural nanowires." The team then collects these mats and uses a laser to etch microscopic circuits into them. They are then sandwiched between electrodes before being encapsulated in a soft, sticky, breathable polymer that may be applied straight to your skin. The biofilm can "plug in" and transform the energy contained in evaporation into enough energy to power tiny gadgets since the surface of our skin is continually wet with perspiration.

According to the researchers, the power source has always been the limiting aspect of wearable electronics. Batteries deplete and must be replaced or recharged. They are also large, massive, and uncomfortably heavy. However, a transparent, tiny, thin, flexible biofilm that generates a constant and consistent source of electricity and may be worn as a Band-Aid or as a patch placed directly to the skin eliminates all of these concerns. During tests, the biofilm skin patch put over sweaty skin produced power similar to that of the salt solution and maintained its performance after 18 hours. Even non-sweating skin produced a significant electric production, suggesting that a continual low-level moisture secretion from the skin is adequate to drive this hydroelectric output. During laboratory tests, the gadget maintained a constant current output for more than 30 days. It might be a potential contender for powering wearable electronics indefinitely.

“It’s much more efficient,” says Derek Lovley, Distinguished Professor of Microbiology at UMass Amherst and one of the paper’s senior authors. “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.”

Credit: University of Massachusetts Amherst