Basswood-anode soil microbial fuel cell-based biosensor for self-sustained and wide-ranged heavy metal detection

Soil microbial fuel cells (SMFCs) offer a promising platform for soil-powered biosensing, but their performance relies on effective electroactive bacterial colonization of the anode. To improve this, four wood types were assessed as porous bio-scaffolds, examining their surface area, pore structure, and microarchitecture before and after carbonization. Basswood showed the most advantageous structure, with uniformly distributed vessels and aligned channels that remained intact after carbonization. The resulting carbonized basswood (CBW) anode exhibited a higher surface area, improved conductivity (12-13.5 mS/cm), and reduced internal resistance. When used in SMFCs, CBW achieved a maximum power density of 30 mW/m² approximately four times higher than non-carbonized carbon felt (NCF) and expanded the heavy-metal detection range by ∼35%. CBW also supported dense, diverse biofilms and maintained stable output for 180 days. These results highlight carbonized basswood as a cost-effective, robust anode material for long-term, self-powered environmental biosensing.