Mixed potential sensors that utilize Ce0.8Gd0.2O1.9 electrolytes and patterned dense 1-mum thick LaMnO3 thin films were studied at 600degreesC and 1%O-2. The response to C3H6 and CO of two different sensor configurations were studied continuously for 1000 h versus an air reference. Although two different current collection schemes and two different metal oxide electrode geometries were employed, the magnitude of the mixed potential generated by both sensors was remarkably similar. From previous work with Au-ceria-Pt mixed potential sensors, this behavior is attributed to precisely controlling the metal oxide electrode/solid electrolyte interface unlike the undefined interface produced when Au electrodes are used. Although doped ceria is not a suitable electrolyte for automotive exhaust gas applications, this work serves to illustrate design goals for zirconia-based sensors.