A sensor device for measuring properties and/or conditions of one or more fluid substances contained, or streamed, inside a fluid vessel, is disclosed. The sensor device generally comprises a main body portion an attachment portion. The main body portion comprises a cavity and at least one sensing element operatively mounted inside the cavity for measuring the properties and/or conditions of the one or more fluid substances and generating data/signals indicative thereof. The attachment portion comprises at least one fluid passage and it is configured to establish fluid communication between a cavity or lumen of the fluid vessel and the cavity of the main body portion through the at least one fluid passage, to thereby enable the one or more fluid substances to interact with the at least one sensing element upon attachment of said sensor device to the fluid vessel.