A Programmable and Printable Microbial Bioelectronic Sensor for Real‐Time and Targeted Pollutant Monitoring in Water

Rapid detection of toxic trace contaminants is critical for global water security, yet routine monitoring relies on costly, time‐consuming laboratory analyses. Microbial sensors offer a promising alternative but suffer from limited specificity, insufficient stability, and slow kinetics. Herein, we report a programmable and printable microbial bioelectronic sensor that overcomes these bottlenecks through multi‐scale chemical design. Using 2,4‐dinitrotoluene as a model pollutant, we genetically reprogrammed the extracellular electron transfer pathway of Shewanella oneidensis by coupling specific pollutant recognition to inner‐membrane cytochrome expression, thereby enabling highly specific bioelectrical detection of target pollutants. For robust deployment, these sensing microbes were encapsulated into a dual‐network hydrogel sustained by reversible hydrogen bonding, ensuring structural resilience and biocompatibility. By 3D‐printing the biosensor into a biomimetic fractal architecture, we minimized mass transport resistance, achieving a response time of 5 min, a 24‐fold acceleration over conventional counterparts. The biosensor also exhibited a low detection limit of 6.75 µg L −1 and a broad dynamic range from 20.4 to 700.0 µg L −1 ( R 2 > 0.999). Crucially, the biosensor maintained high accuracy (relative error < 4.2%) in actual wastewaters. This work establishes that the multiscale chemical design of microbial bioelectronic sensors enables real‐time, targeted pollutant monitoring.