A new tiny bio

“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 can also be rapidly activated by absorbing moisture from the air,” explained Choi, a faculty member in the Department of Electrical and Computer Engineering at the Thomas J. Watson College of Engineering and Applied Science.

“We wanted to make these biobatteries for portable, storable, and on-demand power generation capabilities,” Choi said. “The problem is, how can we provide the long-term storage of bacteria until used? And if that is possible, how would you provide on-demand battery activation for rapid and easy power generation? And how would you improve the power?” he added.

The battery, or more correctly, fuel cell, is about the size of a U.S. dime and is sealed with a strip of Kapton tape, which can endure temperatures between -500 and 750 degrees Fahrenheit. The cell is activated when the tape is removed, and moisture is allowed to enter it. When this happens, the bacteria combined with a chemical germinant are encouraged to generate spores. The researchers found that this process generates enough power to power an LED, a digital thermometer, or a small clock.

The time to reach full power was reduced from one hour to twenty minutes by heating the bacterial spores, and increased electrical output was produced as the humidity level rose. There was a 2% decrease in power production after a week of storage at ambient temperature.

The Office of Naval Research is funding the project, which, it is envisaged, could be used for various military purposes as a power source that could be used in hostile environments or on the battlefield. However, plenty of civilian uses for such a fuel cell would also exist.

These are all positive outcomes, but Choi is aware that for a fuel cell to be a viable alternative to conventional batteries, it needs to power up faster and provide more voltage.

“I think this is a good start,” he said. “Hopefully, we can make a commercial product using these ideas.”