Electrochemical measurements of biofilm development using polypyrrole enhanced flexible sensors

Bacterial biofilms can be beneficial or detrimental, and are capable of forming on virtually any surface. There is a great need for an in situ sensor able to detect and characterize the developmental stages of bacterial biofilms. We have developed an electrochemical approach to detect and characterize bacterial biofilms using polypyrrole (PPy) enhanced flexible biofilm sensors based on organic substrates of Polyethylene terephthalate (PET). PPy films act as a functionalization material on gold electrodes to reduce their electrical impedance thereby enhancing the detection of electrochemical signals. Flexible PET substrates enable sensors to be placed in systems with complex geometries and to be produced using low cost roll-to-roll manufacturing. Measurements of electrochemical impedance spectroscopy (EIS) using the PET flexible biofilm sensors were correlated with fluorescence microscopy using bacteria that express green fluorescent protein (GFP). The biofilm sensors successfully detected the changes of charge transfer resistance and capacitance corresponding to the maturing stages of biofilm development. The charge transfer resistance increases during the early stages of biofilm maturation and decreases in the later stages of development.