Electrochemical Impedance Spectroscopy for Rapid Monitoring of Staphylococcus aureus Proliferation and Bacterial Detection

Biofilms pose challenges such as infection transmission, biofouling, equipment failure, and environmental damage. Despite extensive research, their detection in bioenvironmental systems remains a significant challenge for researchers. Electrochemical impedance spectroscopy (EIS) stands out as an exceptionally sensitive and non-destructive technique for real-time monitoring of biofilms. In this study, we employed EIS to investigate the biofilm formation dynamics of the gram-positive bacterium Staphylococcus aureus (S.aureus) on indium-titanium oxide (ITO)-coated polyethylene terephthalate (PET) conductive substrates. Comprehensive characterization of both control and biofilm-coated substrates was carried out using. The temporal evolution of S.aureus biofilm growth was tracked through EIS measurements, revealing a substantial increase in charge transfer resistance as the biofilm matured. The extracellular electron transfer between the biofilm-coated electrode and the electrolyte was assessed by modulating the EIS bias potential at open circuit potential. Linear response in the charge transfer resistance with increased concentration of S.aureus was studied from 1.0 × 10⁵ to 1.0 × 10⁷ CFU ml⁻¹ with a limit of detection of 3.5 × 10⁴. Overall, this work presents a simple yet highly sensitive biosensor for biofilm detection and growth analysis, eliminating the need for complex substrate modifications.