Disposable cell uses waste water to power bio-sensors
The folded MFC could be used to power biosensors and other small devices for use in challenging field conditions, says Seokheun “Sean” Choi, assistant professor of electrical and computer engineering at Binghamton University, New York (pictured above). Along with two students, he developed a module measuring 6cm across, following an earlier prototype.
“Last time, it was a proof of concept and the power density was in the nanowatt range,” said Choi. “This time, we increased it to the microwatt range. We can light an LED for about 20 minutes or power other types of biosensors.”
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 says. “Ultimately, I’d like to develop instant, disposable, accessible bio-batteries for use in resource-limited regions.”
The new 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 5 cents. The new 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 new design and a lower price tag.
The cell is described in a paper published online in the journal Biosensors and Bioelectronics.