Selectivity-optimization of planar amperometric multi-electrode sensors: identification of O2, NOx and combustible gases in exhausts at high temperatures

Experimental studies and numerical calculations have been performed to describe and optimize the response of planar amperometric multi-electrode sensors. These sensors may be used to detect simultaneously oxygen and NO or oxygen and combustible components. The experimentally determined kinetics of the electrode reaction and the gas phase diffusion have been included in the numerical calculation to optimize the geometry and the operation parameters. An excellent agreement was obtained between modeling and experimental results. The sensor response signal depends strongly on the kinetics of the electrode reaction given by the materials, temperatures, and voltages as well as on the geometry of the cell.