Online monitoring of biofilm growth and activity using a combined multi-channel impedimetric and amperometric sensor

• Real-time, non-destructive monitoring of biofilm growth and metabolic activity.
• Combination of impedance spectroscopy with amperometric activity sensing.
• Pseudomonas aeruginosa biofilm was monitored during several treatments with biocide.
• Biocide treatment reduced the biofilm activity but did not disintegrate the biofilm.
• The system allows detailed biofilm studies measuring activity and thickness.

Biofilms are ubiquitous in water interfaces and therefore influence our daily lives in an ambivalent manner. In medicine, infections can be attributed to biofilm formation. In technical systems, biofilms are causative agents for biocorrosion, contamination, and clogging processes and are responsible for shear force modification in marine systems. To control and manipulate biofilm formation advanced technologies are needed.This paper reports on a novel real-time biofilm monitoring system using custom-made electronics. The system is able to monitor four electrochemical impedance spectroscopy (EIS) electrodes and three amperometric sensors in two microfluidic channels assessing biofilm growth and activity in parallel using Pseudomonas aeruginosa as a model system. The biofilm was characterized during its seeding and growth stages as well as during different injection intervals of a biocide (sodium azide) which allowed monitoring biofilm destabilization and deactivation effects in real time. The results obtained were confirmed by fluorescence microscopy after live/dead cell staining of the bacteria in the measured biofilm.