I’m a saliva, I’m not gon’ give up: Meet the spit-activated battery

On my desk, I can count three things that need recharging on a daily to weekly basis. Wouldn’t it be easier to keep them all topped up if I could just dribble on them whenever they’re a bit low?

I’m a saliva, I’m not gon’ give up: Meet the spit-activated battery

Fortunately for my colleagues, the new spit-activated battery developed by Binghamton University isn’t aimed at me. It’s aimed both at extreme environments where regular batteries don’t function, and developing countries where devices have lower power demands – which is just as well, as the battery can currently provide only a few microwatts per centimetre square. Even a smartphone drenched in saliva would struggle to last for very long.

“On-demand micro-power generation is required especially for point-of-care diagnostic applications in developing countries,” explains Professor Seokheun Choi, who created the battery with his research assistant Maedeh Mohammadifar. “Typically, those applications require only several tens of microwatt-level power for several minutes, but commercial batteries or other energy-harvesting technologies are too expensive and over-qualified. Also, they pose environmental pollution issues.”meet_the_spit-activated_battery_-_1

Here’s how the paper-based bacteria-powered battery works. On the battery are microbial fuel cells containing freeze-dried exoelectrogenic cells. Add saliva and these will come alive within minutes, providing a little power in situations where normal batteries would falter or be overkill.

“The proposed battery has competitive advantages over other conventional power solutions because the biological fluid for on-demand battery activation is readily available even in the most resource-constrained settings, and the freeze-drying technology enables long-term storage of cells without degradation or denaturation,” the researchers explain.

It’s a great start, but obviously increasing the capacity is the main priority. “Although 16 microbial fuel cells connected in a series on a single sheet of paper generated desired values of electrical current and voltage to power a light-emitting diode (LED), further power improvement is required for other electronic applications demanding hundreds of milliwatts of energy,” explains Choi.

This isn’t the first battery we’ve written about that’s helped along by the human body. Back in February, MIT revealed a way of powering ingestible medical devices via stomach acid. While bodily fluids won’t be powering your laptop anytime soon, it does at least show that our literal human resources may have more uses that we currently know of, if we keep thinking outside the box.

Image: Binghamton University, State University of New York

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