Oxygen Transport in Biofilm Electrodes for Screening of Toxic Chemicals

A biosensor electrode system with unique configuration and a thin layer of immobilized yeast cells, set on the surface of an amperometric oxygen membrane electrode, was developed for rapid screening of toxic chemicals in a variety of pollution and process control applications. Measurement is based on the instantaneous detection of changes in oxygen respiratory activity of biofilm of yeast cells upon exposure to toxic chemicals. The design of this electrode system, referred to as biofilm electrodes, was based on a mathematical model of oxygen transport in the biofilm and the electrochemical current response. The biofilm, which consists of three sublayersboundary layer, filter pad, and yeast cell layer-was modeled as a one composite diffusion layer, or three separate layers in series. While the three layer model is more theoretically complete, the one layer model was more reliable and simpler to use.