Measuring acute toxicity using a solid-state microrespirometer Part II. A theoretical framework for the elucidation of metabolic parameters

This work presents the construction of a numerical model that is able to show the behaviour of a biofilm-based microrespirometer. The model uses finite element methods to solve the mass transport equations for oxygen as it travels from the bulk of the solution towards the microelectrode array through the biofilm and a protective Nafion (R) layer, whose main purpose is to avoid electrode fouling. The paper describes some of the issues related to the mass transport at arrays of slightly recessed microelectrodes. It provides further evidence of the validity of the diffusion domain approach as a key resource to model microelectrode arrays. The model is used to interpret amperometric data and provide metabolic rate constants that agree reasonably well with measurements performed in bacterial suspensions under similar experimental conditions. (c) 2008 Elsevier B.V. All rights reserved.