Coupling microbial electrolytic circuit in a microbial electrochemical transistor to amplify extracellular electron signals for rapid BOM detection.

Acquiring weak electron signals from electroactive bacteria is critical for biosensing, wastewater treatment, and life science applications. However, current microbial electrochemical techniques are inefficient in capturing these signals at microscale. While organic electrochemical transistors can amplify signals exponentially, they lack an effective cathodic reaction to sustain electroactive bacterial dominant communities. Hence, a microbial electrochemical transistor is developed, integrating a microbial electrolytic cell with an organic electrochemical transistor by employing platinum source and drain electrodes. This design enables seamless incorporation of microbial electronic circuits into the ion gated circuits. Results demonstrate effective signal amplification of extracellular electrons generated by microbial gates within the device. The extracellular electron signals are successfully acquired across varying concentrations of organic matter, achieving a substantial signal amplification of ≈ 10. The nonlinear relationship between biodegradable organic matter concentrations and device output signals is established. In continuous mode, a detection limit as low as 1 mgL and a rapid response time of less than 60 s are achieved. This novel device facilitates efficient bacterial signal acquisitions on the microscale, bridges microbial electrochemistry with semiconductor physics, opening new avenues for bioelectronic systems in advancing extracellular electron transfer research, and promises in electroactive bacteria identification at even single-cell level.