Abstract: A density sensor (1) to measure the density of a gas having a density ranging from 30 gram per cubic meter to 150 kilogram per cubic meter and a working pressure ranging from 0 to 100 bar comprises: a resonator housing (6) defining a chamber (7) isolated from the gas, the resonator housing (6) comprising an area of reduced thickness defining a membrane (4) separating the chamber (7) from the gas; an actuating/detecting module (5) positioned within the chamber (7) so as to be isolated from the gas and mechanically coupled to the membrane (4); and a resonating element (2) arranged to be immersed in the gas, the resonating element (2) being mechanically coupled to the membrane (9) by a pedestal (3). The membrane (4), the pedestal (3) and the resonator housing (6) are made of metal. The membrane (4) has a thickness enabling transfer of mechanical vibration between the actuating/detecting module (5) and the resonating element (2) through the pedestal (3).

Abstract: A density and viscosity sensor for measuring density and viscosity of a fluid, comprises: a housing (4) defining a chamber (8) isolated from the fluid (3), the housing (4) comprising an area defining a membrane (9) separating the chamber (8) from the fluid (3); a resonating element (5) arranged to be immersed in the fluid (3) and mechanically coupled to the membrane (9); and an actuating/detecting element (6) coupled to the resonating element (5), the actuating/detecting element (6) being positioned within the chamber (8) and mechanically coupled to the membrane (9), the actuating/detecting element (6) comprising at least one piezoelectric element (10) comprising two sides (11, 12) substantially parallel to the membrane (9); The membrane (9) has a thickness enabling transfer of mechanical vibration between the actuating/detecting element (6) and the resonating element (5). One side (11) of the piezoelectric element (10) comprises a single conductive area (13).