Flow-Cell Sensor for Bacteria Detection Using Gate-Modified Organic Electrochemical Transistor

Organic electrochemical transistors (OECT) have been previously demonstrated in the sensing of cells and metabolic products. In this study, we report a novel approach on the universal detection of bacterial contamination in home-liquid-goods through the utilization of a microfluidic flow-cell that has been integrated with OECT technology. The flow-cell device has been developed for the purpose of detecting minimal concentration (~10 ³ CFU/ml) of several bacterium types ( Escherichia coli , Pseudomonas fluorescens and Staphylococcus aureus ) in various commercial household liquid product blends (cf. Air Febreze, Tide, Old Spice bodywash). This process can be completed in a testing period of one hour or less and does not require amplification or a designated binding agent. The flow-cell configuration uses a microporous filter membrane (Au coated PETE, 0.2 μm pore diameter) designed to concentrate the bacteria within the chamber. The membrane also functions as a gate electrode for the operation of OECT. The presence of bacteria on the gate filter membrane leads to an increase in the total effective gate voltage ( V_eff ), which in turn causes a decrease in the OECT source-drain channel current ( I_DS ). Based on the shift of I_DS , the OECT provides good discrimination between bacteria and sterile solutions (0.4 mA difference). The OECT transconductance ( g_m ) exhibits a maximum value at different levels of V_GS for sterile and bacteria solutions. This approach exhibits potential for biosensing systems that will enable real-time monitoring at the production line.