An Organic Electrochemical Transistor to Monitor Salmonella Growth in Real‐Time

Abstract

AbstractOrganic electrochemical transistors (OECTs) are used in research and diagnostic applications due to their facile manufacture, scalability, and biocompatibility. In these devices, the source–drain current upon gate voltage application depends on ion concentration in the electrolyte. This study investigates whether an OECT can be employed to monitor bacterial growth since it is known that the concentration of charged species increases in bacterial cultures during growth. A poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate‐based single‐well OECT, compatible with long‐term incubation of bacterial cultures, is fabricated. It is shown that the growth of Salmonella alters the transfer characteristics of the device and demonstrates how it can be applied to monitor growth in real‐time by recording the source–drain current at gate voltage +0.5 V. The signal can also be measured in filtrates of bacterial cultures, devoid of bacterial cells. This suggests that the signal originates from charged metabolic products. Bacterial biofilm formation does not alter the device response. This proof‐of‐principle study presents OECT recordings as an alternative to optical methods, allowing bacterial growth to be monitored in transparent and opaque media alike. By measuring metabolic products rather than bacterial cell multiplication, insight into the stationary phase and other nondividing states may be obtained in the future.