Biofilm formed on carbon cloth during the test, providing additional evidence that the current measured resulted from the biochemical reaction that was occurring. This is important because the biofilm plays a crucial role in the ability of an MFC to produce current. As biofilm size and thickness increases, current production increases. Bacterial cells metabolize electron-rich substances in a complex process that involves numerous reactions, catalyzed by enzymes. The electrons may then travel freely to the anode through one of many modes of electron transport. Biofilm also helps with the adsorption of the redox molecules to the electrode, which makes it important to have in high power density microbial fuel cells.
Few studies have been performed on power production from paper-based microbial fuel cells that run for few days. Without allowing enough time for biofilm to form, any current and power data that was measured would primarily be associated with extracellular electron transfer, which does not fully represent the electrical power producing capabilities of microbial fuel cells. For the first time, this device demonstrates a longer ability to operate individually and length of use. As such, this is a development that could help expand the number of ways in which microbial fuel cells could be applied.
The Iowa State University research team is currently investigating methods to improve the control of voltage output, as well as creating a constant current. Using controlled tests in a stable environment will aid in the regulation of any output of the system and yield more consistent results. To optimize usability and keep costs down, the scientists would also like to try a device that would not have to use Nafion and Potassium Ferricyanide in any application.
Sources: World Scientific via Science Daily