A team of scientists from Binghamton University, New York has created what they say is a tiny, low cost microbial fuel cell (MFC) that uses a few drops of water to generate power. They claim that the folded MFC could be used to power biosensors and other small devices for challenging field conditions.

“Last time, it was a proof of concept and the power density was in the nanowatt range,” said Seokheun “Sean” Choi, assistant professor of electrical and computer engineering at the university, who, together with a couple of students, developed a module measuring 6cm across, following an earlier prototype. “This time, we increased it to the microwatt range. We can light an LED for about 20 minutes or power other types of biosensors.”

EDNAOL 2016JUN16 POW NT 06 Figure 1: Choi: Commercially available batteries are too wasteful and expensive for the field.

The battery could allow the use of more sophisticated fluorescent or electrochemical biosensors in developing countries, he said. “Commercially available batteries are too wasteful and expensive for the field,” he added. “Ultimately, I’d like to develop instant, disposable, accessible bio-batteries for use in resource-limited regions.”

The innovative design folds into a star with one inlet at its centre and the electrical contacts at the points of each side. After a few drops of dirty water that include the microbes are placed into the inlet, the device can be opened into a Frisbee-like ring to allow each of the eight fuel cells to connect together to improve the power output and simultaneously expose all air-cathodes to the air. Each module is a sandwich of five functional layers with its own anode, proton exchange membrane and air-cathode and the microorganism-containing wastewater is transported into each module through patterned fluidic pathways in the paper layers.

Choi’s original matchbook-sized prototype battery could be produced for about five cents. The ninja star device is more expensive, roughly 70 cents, as it uses carbon cloth for the anode as well as copper tape. The team’s next goal is to produce a fully paper-based device that has the power density of the novel design and a lower cost.