Part of BioVolt's goal in fabricating this particular MFC is to bring down manufacturing, assembly and upkeep costs. One of the first steps in this is finding readily accessible and inexpensive materials that act as substitutes to more costly lab grade chemicals. These substitutes must still fulfill the nutritional requirements for the bacteria, so as to promote growth and energy production. As shown to the right, a media using mainly baking soda, vinegar, and table salt was found to still be an acceptable habitat for growing bacteria.
Geobacter sulfurreducens is an anerobic species of bacteria, meaning it must maintain little or no contact with oxygen. To maintain bacterial growth, the final prototype must also keep the bacteria anerobic. Several tests were done which determined the extent to which the bacteria had to be anerobic. These tests allowed BioVolt to conclude that the bacteria could be kept alive if only exposed to the dissolved oxygen innately present in aqueous solutions. This allowed BioVolt to design the media storage chamber which is able to keep the bacteria away from direct exposure from air, but will expose the bacteria to dissolved oxygen.
Once the bacteria begin to grow in a test tube, they form a thin biofilm on the bottom of the tube. Another test which was conducted was the ability of the bacteria to form this biofilm on solid surfaces which are suspended in the media. Through this study it was concluded that the bacteria were able to grow on any solid surface with which the media comes into contact. This allowed BioVolt to grow a biofilm on the graphite electrodes of the anode without any special treatment.
To study the effect that ambient temeperature has on the bacterial growth kinetics, BioVolt conducted a study of bacterial cultures at two different temperatures, 65 and 86 degrees Ferinheight. This study aided BioVolt in determining the time scale of the bacterial growth phase. This study also determined that the bacterial growth kinetics is not strongly dependent on temperature over the range of 65 to 86 degrees Ferinheight.
To optimize the design of the final prototype, BioVolt constructed five separate research MFCs. These MFCs were designed to enable high throughput testing for different variables such as media composition, electrode area to cell volume, and cathode fluid. These research prototypes aided BioVolt in making many important design decisions for the final MFC prototype.