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5th August 2017

Saliva battery is a mouth-watering prospect

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Researchers at a New York university have come within spitting distance of developing a more environmentally friendly battery that runs on saliva.

The team at Binghamton University, State University of New York, have reached the next stage in producing microbial fuel cells (MFCs): a battery activated by spit that can be used in extreme conditions where normal batteries can’t function.

Professor Seokheun Choi, electrical and computer science assistant at the university, has spent the past five years focussing on developing micro-power sources for use in resource-limited regions and has created several paper-based bacteria-powered batteries.

Professor Choi said: “On-demand micro-power generation is required especially for point-of-care diagnostic applications in developing countries.

“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.”

Professor Choi and research assistant Maedeh Mohammadifar, have designed a high-performance, paper-based, bacteria-powered battery by building microbial fuel cells with inactive, freeze-dried exoelectrogenic cells. This generates power within minutes of adding saliva.

The researchers wrote a paper which was published in Advanced Materials Technology, in which they said: “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.”

Professor Choi added: “Now, our power density is about a few microwatts per centimetre square. 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.”