OPTICAL SENSOR DEVICE FOR FLUID SUBSTANCES

An optical sensor device (1) for a fluid substance (LS) comprises a device body (2) having a detection portion (14), associated to which is a sensitive optical part that comprises at least one of an emitter (20) and a receiver (21) of an optical radiation (Re, Rr). The detection portion (14) is made of a material transparent to the optical radiation (Re, Rr) and has an inner surface (23a, 23b) and an outer surface (15), the outer surface (15) being designed to be in contact with the fluid substance (LS) and the inner surface (23a, 23b) being designed to be isolated from the fluid substance. The at least one of the emitter (20) and the receiver (21) of the sensitive optical part is optically coupled to the inner surface (23a, 23b) of the detection portion (14), in such a way that the optical radiation (Re, Rr) is at least in part propagated through the detection portion (14), in particular with an angle and/or an intensity that is variable as a function of a characteristic of the fluid substance. The optical sensor device (1) comprises a protection arrangement, configured for preventing possible deformation of the detection portion (14) caused by an increase in volume of the fluid substance (LS), in particular deformation of at least one of its inner surface (23a, 23b) and its outer surface (15). The protection arrangement comprises at least one compensation element (13) having an elastically deformable body, which is able to contract, for compensating thereby a possible increase in volume of the fluid substance (LS) or else for enabling a reversible displacement of the detection portion (14) following upon a possible increase in volume of the fluid substance (LS).