Membrane‐electrode assembly enhances performance of a microbial fuel cell type biological oxygen demand sensor

A membrane‐electrode assembly (MEA) was applied to a microbial fuel cell (MFC) type biological oxygen demand (BOD) sensor and the performance of the sensor was assessed. To establish the optimal conditions for MEA fabrication, platinum‐catalysed carbon cloth cathodic electrodes were assembled with cation exchange membranes under various temperatures and pressures. By analysing coulombs from the MFCs, it could be determined that the optimal hot‐pressing conditions were 120 °C and 150 kg cm−2 for 30 s. When the MEA fabricated under optimal conditions and an air cathode were utilized for the construction of the MFC type BOD sensor, coulombs increased to 4.65 C from 0.52 C and power increased to 69,080 mW m−3 from 880 mW m−3 (at a BOD concentration of 200 mg L−1), respectively, compared with the conventional MFC lacking a MEA. The increased power improved the performance of the MFC type BOD sensor: sensitivity increased from 1.2 × 10−3 to 1.8 × 10−2 C per mg L−1 of BOD, with good linearity (r2 = 0.97) and over 97% repeatability. We conclude that the MEA can be successfully applied to MFCs to make them highly sensitive BOD sensors.