A sensor assembly comprises a substrate arrangement and a sensor chip mounted to the substrate arrangement. A sensing element is integrated on or in the sensor chip and is sensitive to at least one parameter of a fluid. An access opening is provided in the substrate arrangement enabling the fluid to access the sensing element. A metallization arranged on at least a portion of the substrate arrangement seals a chamber containing the sensor chip which portion comprises one or more of a wall defining the access opening or an area facing the sensor chip.