An electrochemical technique to measure local flow velocity in biofilms

The limiting current technique and a mobile microelectrode were used to measure local flow velocity in biofilms. The microelectrode was calibrated using the particle tracking technique in conjunction with confocal scanning laser microscopy (CSLM). A relationship between the limiting current density and the local flow velocity was found using nonlinear regression. This relationship was the same whether biofilm was present or not. Therefore, we used the measurements of limiting current density to evaluate flow velocity distribution around biofilm clusters. The flow velocity distribution was affected by the geometry of interstitial voids and by their orientation with respect to the flow direction in the main conduit. Flow velocity measurements using the limiting current technique were faster than similar measurements using particle tracking with confocal scanning laser microscopy.