Single Chamber MFC Biosensor for Cobalt Using Microbial Agar Anodes

Abstract

This study evaluates agar and microorganism–agar anodes in a single chamber microbial fuel cell (MFC) as a platform for cobalt biosensing, using cyclic voltammetry (CV) over 5–200 mV·s⁻¹ at various exposure stages. Across all conditions, voltammograms were studied evidencing capacitive, surface controlled behaviour rather than resolved Faradaic processes. Quantitative and qualitative analysis of Agar shows low currents (10⁻⁷–10⁻⁶ A) and narrow hysteresis, with cobalt mainly causing a uniform current increase attributed to enhanced electrolyte conductivity. In contrast, microorganism agar exhibits a higher magnitude of currents (up to 10⁻⁵ A) and broader loops at various scan rates, cobalt induces a stronger and more persistent amplification of this capacitive envelope than in agar, demonstrating that the microbial biofilm governs heavy metal induced electrochemical modulation. These results establish a robust cobalt modulated capacitive baseline and identify MA as a promising bioanode for self-powered heavy metal sensing in MFCs.