Recent Advances in Analytical Platform for Single-Cell Microbial Electrochemistry

The urgent need to mitigate global energy and environmental crises underscores the importance of developing clean and sustainable energy technologies. Microbial electrochemical systems (MESs) have emerged as a promising platform, exploiting the ability of electroactive microorganisms to exchange electrons with electrodes through extracellular electron transfer (EET). While conventional studies have primarily focused on community-level processes, they often overlook the intrinsic heterogeneity and dynamic behaviors of individual cells that ultimately govern MES performance. To overcome these limitations, single-cell analytical approaches are being developed, though their application to EET studies remains in its infancy. This review provides a comprehensive summary of current single-cell microbial electrochemistry studying techniques, beginning with the fundamental mechanisms of EET and progressing to electrochemical microelectrode methods and optical imaging strategies. Particular attention is given to both label-free and probe-labeled imaging approaches, each offering distinct advantages. Finally, we briefly discuss the interplay between EET and microbial behaviors at single-cell scale. These insights highlight emerging methodologies for probing single-cell EET, their applications in uncovering microbial physiology and behaviors, and the future opportunities they open for advancing microbial electrochemistry and the rational design of MESs.