This disclosure relates to a medical device including, a hard part, a converter, and a conductive path. The hard part has fluid paths for guiding a medical fluid, in particular blood, through the hard part. The converter is arranged to measure a characteristic of the medical fluid while the fluid is present in one of the fluid paths. At least a first section of the converter or of the conductive path is applied to or superimposed on the hard part by a first additive application method. At least a second section of the converter or of the conductive path is applied to the hard part by a second application method. The first and the second additive application methods differ from each other.