Modeling and optimization of diffusive layers in potentiometric and amperometric electrochemical gas sensors

A physicochemical model of the behavior of electrochemical gas sensors based in a solid-state ion conducting electrolyte is presented and verified. The model focuses on air-referenced planar sensors with a porous, diffusive layer covering one of the electrodes. By assuming hypotheses of ergodicity, ordinary diffusion, near-equilibrium situation, high catalytic activity and steady-state mass conservation in the system layer/electrode/electrolyte/electrode, the model describes the current-voltage characteristics both in steady-state as in transient conditions. Numerical simulations, including finite element modelling, are used for obtaining the model preditions for I(V), I(t) and V(t) responses in front of binary O-2-N-2 mixtures and multi-component mixtures. The model is validated with our own-designed sensors with different diffusion layers. (C) Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.