Abstract: A sensor for measuring the mixture ratio of liquids, particularly of fuel mixtures, comprises a measuring cell, which has a cavity with one inlet and one outlet. The liquid is directed through the cavity, whereby regions of the inner wall of the cavity are electrically conductive and, together with at least one additional electrically conductive surface, form a capacitor, which is a component of an evaluation circuit. The measuring cell is manufactured from at least two ceramic carriers, which are connected by way of at least one connection layer to form a layer arrangement. The cavity is produced between the ceramic carriers as the result of the lack of at least one connection layer in certain regions. In each case, at least one electrode is applied, in the vicinity of the cavity, to the ceramic carrier delimiting the cavity using thick-film technology.