Bacteria detection in a Kretschmann geometry flow cell at a plasmon-enhanced interface with spectroscopic ellipsometer

In this work, we investigate whether bacteria can be substantially examined in liquid environment with an ellipsometer in the visible wavelength range. For that investigation a Kretschmann type flow cell was used in which the paths of illuminated and reflected light beams are on the substrate side. To enhance the sensitivity a thin gold layer was applied on the top of glass substrate and the measurement was performed by using surface plasmon polaritons. Porphyrin functionalized coating layers were employed to analyze their performance to capture bacteria and to study the stability and repeatability of the optical response with regard to the ellipsometric measurement. Escherichia coli (E. coli) bacteria were used as first model bacteria and their deposition on the sensing surface was monitored in a real-time measurement in a liquid environment.