A method and device are disclosed for calibrating sensors, which sensors are arranged on semiconductor chips and are e.g. to be used for detecting a substance in a fluid. The sensors are calibrated while they are still assembled on a semiconductor wafer by exposing the wafer to a calibration fluid containing a known amount of the substance to be measured. Hence, rather than first cutting the wafer, the sensors are calibrated at an early stage. For this purpose, they are placed on a chuck below a lid. The calibration fluid with known parameters is introduced between the wafer and the lid. This allows to test and calibrate a large number of sensors quickly.