This presentation will describe the development and optimisation of microbial fuel cell (MFC)-based sensors for real-time measurement of biochemical oxygen demand (BOD) in wastewater. Conventional BOD analysis relies on laboratory tests with long turnaround times, limiting its usefulness for process control and early warning at treatment works. MFC sensors offer a self-powered alternative, where electroactive biofilms convert biodegradable organic matter directly into an electrical signal correlated with BOD. We report how electrode design was systematically optimised to improve sensitivity, stability and operational robustness under realistic conditions. A macroporous 3D-printed anode was used to enhance biofilm attachment and mass transfer, while alternative low-cost air-cathode catalysts were evaluated to reduce reliance on platinum and improve long-term performance. The combined design showed improved signal stability, wider linear response ranges and reliable operation when tested with real urban wastewater. The work demonstrates that careful engineering of both anode and cathode materials can overcome key limitations that have previously restricted MFC sensors to laboratory studies. The results highlight the potential of these sensors as low-cost, autonomous tools for continuous monitoring of organic load in wastewater treatment plants, supporting smarter aeration control and improved process efficiency.