To overcome limitations that might stem from safe access to electricity, research was presented this week at a meeting of the American Chemical Society surrounding the development of a new type of battery made of paper and fueled by bacteria. According to Sean Choi, Ph.D., “Paper has unique advantages as a material for biosensors. It is inexpensive, disposable, flexible, and has a high surface area. However, sophisticated sensors require a power supply. Commercial batteries are too wasteful and expensive, and they can’t be integrated into paper substrates. The best solution is a paper-based bio-battery.”
Researchers have previously developed disposable paper-based biosensors for diagnosing diseases and detecting environmental contaminants. Such devices typically rely on color changes to report a result, with effectiveness varying based on their sensitivity. To boost sensitivity, the biosensors require power. Choi wanted to develop a less expensive paper battery powered by bacteria that could be incorporated into these simple devices.
Choi and his team created the battery by printing thin layers of metals and other materials onto a paper surface. Then, they placed freeze-dried exoelectrogens, which are a type of bacteria that can transfer electrons outside of their cells, to the paper. The electrons are generated when the bacteria make energy for themselves and move through the cell membrane. They can then make contact with electrodes outside of the membrane in providing power for the battery.
The team added saliva or water to activate the battery. Within minutes the liquid revived the bacteria, which then produced a significant quantity of electrons to power an LED and calculator.
Researchers also investigated how oxygen impacts the device’s performance. Oxygen, which passes through paper, could soak up electrons produced by the bacteria before reaching the electrode. The team found that oxygen slightly decreased power generation because the bacterial cells were tightly attached to the paper fibers. This meant that the electrons were quickly moved away to the anode before oxygen could intervene.
The paper battery, which can only be used once, has a lifespan of about four months. Choi is working on conditions to improve the longevity and performance of the freeze-dried bacteria, which would extend the shelf life. The researchers acknowledge funding and additional support from the Office of Naval Research, the Research Foundation for the State University of New York, and the National Science Foundation.
Image Credit: Binghamton University / http://ws.binghamton.edu/choi/paper%20devices.html