Perspectives on Atomic Force Microscopy for Investigating Microbial Extracellular Electron Transfer

ABSTRACT Extracellular electron transfer (EET) in electroactive microorganisms plays a critical role in the bioenergy conversion processes of bioelectrochemical systems. Atomic force microscopy (AFM) has emerged as a powerful tool for probing microbial ultrastructure and electrical properties, particularly for resolving conductive features such as bacterial nanowires at the nanoscale. However, real‐time in situ characterization of dynamic EET processes under physiologically relevant aqueous conditions remains technically challenging. This perspective summarizes recent advances in multimodal AFM techniques, with particular emphasis on electrical and electrochemical AFM approaches for investigating EET mechanisms at the single‐cell level. We further discuss the opportunities and limitations of aqueous AFM measurements and integrated AFM platforms that enable enhanced electron transfer detection with micro‐ to nanoscale spatial resolution and molecular sensitivity. These developments provide new opportunities for the direct visualization and quantitative analysis of EET processes in living microbial systems. Continued progress in AFM‐based methodologies will advance the mechanistic understanding of microbial electroactivity and support the development of high‐efficiency bioelectrochemical systems, including microbial fuel cells.