Bacteria-powered battery built on single sheet of paper

Scientists have developed a bacteria-powered battery on a single sheet of paper that can power disposable electronics such as diagnostic sensors.
The manufacturing technique reduces fabrication time and cost, and the design could revolutionise the use of bio-batteries as a power source in remote, dangerous and resource-limited areas, researchers said.
"Papertronics have recently emerged as a simple and low-cost way to power disposable point-of-care diagnostic sensors," said Seokheun Choi, Assistant Professor at Binghamton University in the US.
"Stand-alone and self-sustained, paper-based, point-of-care devices are essential to providing effective and life-saving treatments in resource-limited settings," said Choi.
On one half of a piece of chromatography paper, Choi and PhD candidate Yang Gao, placed a ribbon of silver nitrate underneath a thin layer of wax to create a cathode.

They then made a reservoir out of a conductive polymer on the other half of the paper, which acted as the anode.

Once properly folded and a few drops of bacteria-filled liquid are added, the microbes' cellular respiration powers the battery.
"The device requires layers to include components, such as the anode, cathode and PEM (proton exchange membrane)," said Choi.
"(The final battery) demands manual assembly, and there are potential issues such as misalignment of paper layers and vertical discontinuity between layers, which ultimately decrease power generation," Choi said.
Different folding and stacking methods can significantly improve power and current outputs. Scientists were able to generate 31.51 microwatts at 125.53 microamps with six batteries in three parallel series and 44.85 microwatts at 105.89 microamps in a 6x6 configuration.

It would take millions of paper batteries to power a common 40-watt light bulb, but on the battlefield or in a disaster situation, usability and portability is paramount.
There is enough power to run biosensors that monitor glucose levels in diabetes patients, detect pathogens in a body or perform other life-saving functions.
"Among many flexible and integrative paper-based batteries with a large upside, paper-based microbial fuel cell technology is arguably the most underdeveloped," said Choi.
"We are excited about this because microorganisms can harvest electrical power from any type of biodegradable source, like wastewater, that is readily available. I believe this type of paper biobattery can be a future power source for papertronics," Choi added.

The research was published in the journal Advanced Materials Technologies.