Sensor element for determining the concentration of oxygen in gas mixtures and process for producing same

The invention relates to a sensor element for determining the concentration of gas components in gas mixtures, especially the oxygen concentration in exhaust gas of internal combustion engines. The sensor element contains a pump cell which pumps oxygen into or out of a measuring gas chamber, a concentration cell with a reference electrode that is arranged in a reference gas channel as well as a measuring electrode. The measuring gas chamber and the reference gas channel are located in the same layer level of the sensor element and are separated from one another by means of a partition wall which is produced by applying a ceramic paste onto an adjacent solid-electrolyte film.