Scientists at Binghamton University, State University of New York, have used a species of spore-forming bacterium called Bacillus subtilis to create a small-scale battery-like microbial fuel cell that potentially would still work after 100 years.
Small-scale battery-like microbial fuel cells are a promising alternative power source for future low-power electronics. Controllable microbial electrocatalytic activity in a miniaturized microbial fuel cell with unlimited biodegradable energy resources would enable simple power generation in various environmental settings. However, the short shelf-life of living biocatalysts, few ways to activate the stored biocatalysts, and extremely low electrocatalytic capabilities render the miniature microbial fuel cells unsuitable for practical use. In new research, heat-activated Bacillus subtilis spores are revolutionarily used as a dormant biocatalyst that can survive storage and rapidly germinate when exposed to special nutrients that are preloaded in the device. Image credit: Maryam Rezaie & Seokheun Choi, doi: 10.1002/smll.202301135.
“The overall objective is to develop a microbial fuel cell that can be stored for a relatively long period without degradation of biocatalytic activity and also can be rapidly activated by absorbing moisture from the air,” said Professor Seokheun ‘Sean’ Choi, senior author of the study.
“We wanted to make these biobatteries for portable, storable and on-demand power generation capabilities.”
“The problem is, how can we provide the long-term storage of bacteria until used?”
“And if that is possible, then how would you provide on-demand battery activation for rapid and easy power generation? And how would you improve the power?”
The dime-sized fuel cell was sealed with a piece of Kapton tape, a material that can withstand temperatures from 4 to 673 K.
When the tape was removed and moisture allowed in, the bacteria mixed with a chemical germinant that encouraged the microbes to produce spores.
The energy from that reaction produced enough to power an LED, a digital thermometer or a small clock.
Heat activation of the bacterial spores cut the time to full power from 1 hour to 20 minutes, and increasing the humidity led to higher electrical output.
After a week of storage at room temperature, there was only a 2% drop in power generation.
“Our study is funded by the Office of Naval Research, and it’s easy to imagine the military applications for a power source that could be deployed on the battlefield or in remote locations,” said Professor Choi and first author Maryam Rezaie.
“However, there would be plenty of civilian uses for such a fuel cell, too.”
“While these are all good results, we know that a fuel cell like this needs to power up more quickly and produce more voltage to become a viable alternative to traditional batteries.”
“I think this is a good start,” Professor Choi added.
“Hopefully, we can make a commercial product using these ideas.”
Their paper was published in the journal Small.
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Maryam Rezaie & Seokheun Choi. Moisture-Enabled Germination of Heat-Activated Bacillus Endospores for Rapid and Practical Bioelectricity Generation: Toward Portable, Storable Bacteria-Powered Biobatteries. Small, published online March 18, 2023; doi: 10.1002/smll.202301135
