This invention relates to a sensor for the detection of liquid ingredients with a carrier element (10), a sensor element (1) on the carrier element (10) and a sensor array, which is disposed on the surface of the sensor element and contains one or more electrodes (2), which are in electrical contact (4) with the corresponding deflection surfaces (3), which are also on the surface of the sensor element (1), but otherwise not electrically connected to the carrier element (10). The sensor forms a detection unit together with a detachable cover, which has at least one fluid channel (7) for the feed line, as well as at least one contacting element (5) and which forms together with the sensor at least one hollow space (8) above the surface of the sensor element (1), where there is the surface or part of a surface of at least one electrode (2), but no deflection surface (3), while each contacting element is in such a manner disposed, that it contacts a corresponding deflection surface when the sensor connects with the cover. In specific embodiments, the sensor itself comprises in addition a covering element (6) firmly attached to the sensor, which constitutes at least one filling opening (12) and at least one hollow space (8) above a sensor element's surface (1), where there is the surface or part of a surface of at least one electrode (2), but no deflection surface (3). When connecting this sensor to a contacting element (5), it forms a detection unit, whereby each contacting element is in such a manner disposed, that it can connect to a corresponding deflection surface (3) of the sensor.