Revolutionary self-powered transducing mechanism for long-lasting and stable glucose monitoring: achieving selective and sensitive bacterial endospore germination in microengineered paper-based platforms.

We introduce a groundbreaking proof-of-concept for a novel glucose monitoring transducing mechanism, marking the first demonstration of a spore-forming microbial whole-cell sensing platform. The approach uses selective and sensitive germination of Bacillus subtilis spores in response to glucose in potassium-rich bodily fluids such as sweat. As the rate of germination and the number of metabolically active germinating cells are directly proportional to glucose concentration, the electrogenic activity of these cells-manifested as electricity-serves as a self-powered transducing signal for glucose detection. Within a microengineered, paper-based microbial fuel cell (MFC), these electrical power outputs are measurable and can be visually displayed through a compact interface, providing real-time alerts. The dormant spores extend shelf-life, and the self-replicating bacteria ensure robustness. The MFC demonstrated a remarkable sensitivity of 2.246 µW·(log mM)^-1·cm^-2 to glucose concentrations ranging from 0.2 to 10 mM, with a notably lower limit of detection at ~0.07 mM. The sensor exhibited exceptional selectivity, accurately detecting glucose even in the presence of various interferents. Comparative analyses revealed that, unlike conventional enzymatic biosensors whose performance degrades significantly through time even when inactive, the spore-based MFC is stable for extended periods and promptly regains functionality when needed. This preliminary investigation indicates that the spore-forming microbial whole-cell sensing strategy holds considerable promise for efficient diabetes management and can be extended toward noninvasive wearable monitoring, overcoming critical challenges of current technologies and paving the way for advanced biosensing applications.