Influence of the hydrodynamics on the biofilm formation by mass transport analysis.

Biofilm are formed wherever there is some water in our environment: pipes, pipelines, tap water systems, air conditioning systems... Furthermore, the ecological and economical consequences are very important: energy losses, bacterial contamination, material deterioration. The aim of this work is to develop a new method to detect and monitor the biofilm formation. This method can also determine some mechanical properties of the biofilm. An application of this method is a realization of a biofilm sensor. Biofilm is considered as an inert porous layer with respect to mass transport. In our experiment, the biofilm is grown on a gold electrode in natural seawater. Its thickness is determined by considering the oxygen diffusion limiting current measured for different rotation speeds on this electrode. Two different incubators are used during the biofilm development: one, with a laminar flow, permits the rotation of the electrode during the biofilm formation, and for the second, a tube is used under turbulent conditions during the biofilm formation. This experiment allows us to characterize the mechanical behavior (thickness, elasticity, rigidity) of the biofilm in function of different conditions of development.