System and methods of measuring properties of fluids

A multi-sensor device for monitoring a fluid substance, said multi-sensor device comprising:

• a main body structure having at least one fluid port and a fluid passage for receiving a stream of said fluid substance and flowing it through said fluid passage, and one or more openings for establishing fluid communication with said fluid passage;
• a sensing assembly attached to said main body structure, said sensing assembly comprising:
• a base element attached to the main body structure, said base element having a respective pass-through hole for each of the one or more openings of the main body structure for fluidically communicating between said one or more openings and said respective pass-through hole;
• a sensing foil/film having one or more sensor elements, wherein each portion of said sensing foil/film having at least one of said one or more sensor elements is in fluid communication with at least one of said one or more openings via its respective pass-through bore, to thereby enable each of said one or more sensor elements to measure at least one property or condition of said fluid substance and generate sensor data/signals indicative thereof;
• and
• a cover element attached to the base element with the sensing film/foil sandwiched therebetween;
• and
• an enclosure assembly configured to receive said main body structure and said sensing assembly attached thereto, said main body structure and sensing assembly attached thereto configured as an insertable and removable/exchangeable element operable to electrically connect between said sensing foil/film of the sensing assembly and circuitry of said enclosure assembly.