The bacteria-powered batteries of electrical engineer Seokheun Choi have taken on a number of interesting forms, including matchbooks, folding paper and ninja stars. For the first time, the Binghamton University researcher has now woven his innovative fuel cells into a flexible and stretchable piece of fabric that could one day power wearable electronics through our body's own bacteria.

Choi's bacteria-powered batteries rely on what are known as microbial fuel cells (MFCs). These types of cells use bacteria to trigger reduction/oxidation reactions, which swap electrons between molecules to generate electricity. In his previous work, he has tapped dirty water and saliva for this purpose, and for his latest trick is turning to the bacterial cells found in human sweat.

"Among many flexible and integrative textile-based batteries and energy storage devices, MFCs are arguably the most underdeveloped for wearable electronic applications because microbial cytotoxicity may pose health concerns," Choi tells New Atlas. "In the literature, reported work on the wearable MFCs was either unavailable or quite limited. However, if we consider that humans possess more bacterial cells than human cells in their bodies (3.8×1013 compared to 3.0×1013), the direct use of bacterial cells as a power resource interdependently with the human body is conceivable for wearable electronics."

Choi investigated the possibilities by building his MFCs into a twistable, stretchable textile-based battery that uses the bacterium Pseudomonas aeruginosa as a catalyst. The resulting device has a maximum power output of 6.4 µW cm−2, which is similar to his other flexible, paper-based MFCs. It also demonstrates stable, lasting performance even when bent out of shape repeatedly. We asked him to expand on the design.

"All my previous experiences and technologies on paper-based bio-batteries have been leveraged to develop for the first time an entirely textile-based bio-battery," Choi tells us. "All battery components were monolithically incorporated into a single sheet of fabric by precisely controlling the depth of each component. The structure consisted of the anode and cathode placed in a single reaction chamber with no separating membrane. The anodic chamber was specifically engineered to be conductive and hydrophilic for electricity harvesting from bacterial cells in liquid, while the cathode used the silver oxide and silver redox couple as a solid-state material for textile-based electronics."

One advantage of the single-chamber membrane-free approach, which is a departure from typical battery design, is that it makes production of the actual battery itself a lot simpler. Using a batch fabrication approach, Choi and his team were able to simultaneously construct 35 separate devices, and the researchers say this kind of approach could revolutionize the mass production of textile MFCs.

The research was published in the journal Advanced Energy Materials.