Mesoporous PU/PEDOT:PSS Electrodes Reveal Population‐Level Stochastic Bioelectrical Dynamics in Marine Diatoms

Abstract

ABSTRACT Understanding how microbial populations generate and modulate electrical signals remains a major technical challenge because extracellular ionic processes are inherently weak, spatially distributed and stochastic. Here, we introduce a mesoporous ultra‐low‐impedance PEDOT:PSS electrode that exploits volumetric ionic‐electronic coupling to probe stochastic electrochemical dynamics in axenic populations of the marine model diatom Phaeodactylum tricornutum . The three‐dimensional porous architecture provides a large electrochemically accessible surface area with high capacitance and low impedance, enabling sensitive detection of non‐equilibrium current fluctuations under applied bias. Applied bias systematically amplifies stochastic electrical fluctuations, while living diatoms significantly modify their amplitude and temporal statistics. Noise analysis reveals enhanced low‐frequency fluctuations, increased power‐law exponents and higher transient‐event rates, indicating biologically driven perturbations of the local electrochemical environment. Pharmacological inhibition with tetraethylammonium suppresses spontaneous electrical activity, providing independent functional evidence that membrane‐associated potassium‐dependent processes contribute to the measured signals. Increasing diatom cell density further produces progressively larger spectral exponents and distinct changes in stochastic‐event dynamics, demonstrating that these electrical signatures encode microbial population density. These findings establish stochastic electrochemical noise as a sensitive, label‐free probe of microbial bioelectrochemical activity and a bioelectronic strategy for monitoring living microbial systems through their intrinsic non‐equilibrium electrical fluctuations.