A sensor device for a container of a liquid substance comprises a body with a housing portion having a closing structure, the body having an inner surface and an outer surface. The housing portion is pre-arranged for assembly on the container, in such a way that a portion of the outer surface of the body faces the inside of the container to be in contact with the liquid substance, and the inner surface of the body is isolated from the inside of the container. Associated to the body is a first arrangement for detection of the level of the substance.Associated to the body of the device is a second arrangement for detection of a characteristic of the liquid substance, which comprises an emitter and a receiver of a given optical radiation. A first portion of the body of the device is made of a material designed for propagation of the given optical radiation, the emitter and the receiver being optically coupled to the inner surface of the body at the first portion. The first portion of the body of the device is shaped to contribute to propagation of the given optical radiation from the emitter to the receiver, in such a way that the given optical radiation is propagated through the first portion of the body of the device towards the receiver, at an angle and/or with an intensity that are/is variable as a function of the characteristic of the liquid substance.