"Remove the Kapton tape and activate the battery." "But captain, these batteries must be 100 years old!" "They'll work, trust me."
That may sound like a scene from a Star Trek rerun, but it could actually be one that unfolds sometime in Earth's future. That's because researchers have just developed a battery that could be stored up to 100 years before being successfully activated. The secret lies in sealing up dormant bacteria until it's time for them to be called into power-generating service.
The new biobattery builds on previous work conducted at Binghamton University (BU) in which a research team led by Seokheun Choi created an edible battery that was activated when a pH-sensitive membrane dissolved in the small intestine. That caused Bacillus subtilis bacteria to come to life and begin producing spores – a process that generates enough electricity to power small sensors, such as cameras that could be used to monitor gut health.
Bacteria-based batteries are known as microbial fuel cells or MFCs, and Choi has previously created versions that operated on the body's own bacteria or saliva to generate electricity, as well an origami-like version that runs on dirty water.
In the latest round of research, Choi's team (based out of BU's Bioelectronics and Microsystems Laboratory) once again used bacteria's ability to stay dormant until given the right conditions to function. This time, however, the scientists focused on making a battery that would function outside the body and be useful even after decades on the shelf.
"We wanted to make these biobatteries for portable, storable and on-demand power generation capabilities," said Choi. "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?"
To answer those questions, the team encased Bacillus subtilis in a graphene hydrogel that excels at grabbing moisture from the air. They then sealed up the fuel-cell assembly with a piece of Kapton tape, which can function in temperatures ranging from -500 to 750 °F (-296 to 399 °C). Once the tape was removed, the hydrogel funneled moisture to the bacteria, causing them to begin manufacturing spores.
After an hour, the battery had enough electricity to power an LED light, a thermometer and small digital hygrometer. Heating the fuel cell cut the time to full power to 20 minutes. Plus, after a week of being stored at room temperature, the activated battery had only lost 2% of its power.
The ability to last a week without losing much power once activated is certainly impressive. An even greater claim to fame for the tiny biobattery, however, is the fact that the researchers believe it could remain in its unactivated state for up to 100 years and still function perfectly, as long as there's enough moisture in the air to activate the bacteria once the tape is removed.
The research was funded by the Office of Naval Research and has been published in the journal, Small.
Source: Binghamton University
