Anode modification to improve the performance of a microbial fuel cell volatile fatty acid biosensor

The development of a simple and low cost sensor such as a microbial fuel cell (MFC) to measure short chain volatile fatty acids (VFAs) would enable the implementation of this important bioprocess parameter. However using microbial fuel cells (MFCs) as transducers requires consistent microbial biocatalysis at the anode. This study considers carbon/conductive polymer composite electrodes as a mechanism to ensure the sensor signal has temporal stability, repeatability and a short response time to variations in concentration of acetic, propionic and butyric acid. The immobilization of bacteria by; modifying the carbon surface with functionalized poly(pyrrole) coatings, increasing and holding the total number of negatively charged bacteria on the electrode; or by using natural polymers with mediators covering the pre-acclimated microbial community to improve catalytic action and to protect them from the sample matrix was investigated. Six different natural polymers and/or electropolymers anode configurations were compared and it was found that poly(pyrrole-alkyl ammonium) accelerates start-up of MFC based sensors and provided improved stability, repeatability and recovery shorter signal response.