The battery is a microbial fuel cell. These are bio-electrochemical systems that drive a current by using bacteria. The cells function by copying the bacterial interactions that occur in the natural world. Essentially the fuel cells are devices that convert chemical energy to electrical energy by the action of microorganisms.
The newly developed device is designed to run on just a few drops of water. Here any water is suitable, even ‘dirty’ rainwater or water from a puddle. The efficiency of the battery relates to its design. STEAM Register (@STEAMRegister) provides a short excerpt of the battery being manipulated, via Twitter.
This #origami ninja star is actually a microbial fuel cell #nanotechnology pic.twitter.com/o8LWZ2RxGp
— STEAM Register (@STEAMRegister) June 10, 2016
The design began with a battery resembling a small box (much like a matchbox). It was later found that alternative shapes were more power efficient. This led to the present ‘ninja star version.’ The battery measures about 2.5 inches wide and it is designed to function with eight small batteries connected in a series. The shape provides efficiency by virtue of the star being at the center, with electrical contacts at the points of each side.
Through this, by utilizing power in the microwatt range, the research team were able to power an LED for about 20 minutes. This provides the basis for controlling various biosensors. A biosensor is a device that utilizes biological components, such as enzymes to indicate the amount of a biomaterial present. An example is with a pregnancy testing kit or a test for a virus like HIV.
One limitation with such tests are their level of sensitivity. The new bio-battery should allow for the application of more sophisticated fluorescent or electrochemical biosensors. This could be particularly useful in the field or in developing countries where commercial batteries are too expensive or they do not work away from a city-base.
The battery can also be produced at a relatively low cost, in the region of less than $1 (U.S.) This is because the basic structure is filter paper, a carbon cloth and some copper tape.
The research was performed at Binghamton University, State University of New York. The findings are published in the journal Biosensors and Bioelectronics, in a paper headed “A disposable power source in resource-limited environments: A paper-based biobattery generating electricity from wastewater.”
