Measuring Internal Resistance of a Microbial Fuel Cell

We have developed a new means of quantifying the internal resistance of the microbial fuel cells. There is reason to believe that current methods for measuring the internal resistance of microbial fuel cells, such as current injection or electrochemical impedance spectroscopy (EIS), neglect a portion of the activation resistance. We propose a capacitor method as an alternative solution to this issue. Internal resistance is found by charging an external capacitor and fitting the charging curve. This method will reflect the true characteristic value of the internal resistance, because the time scale of the measurement will be consistent with the time scale of the growth of the cells. Early data analysis shows that the internal resistance obtained by the capacitor method is greater than that determined by EIS. Furthermore, for the controls performed without a biofilm present at the anode the internal resistance values found using EIS are the same as those found by the capacitor method. This suggests that the capacitor method may more accurately determine the resistance due to microbial activity.