An optical sensor device for detection of at least one characteristic of a liquid substance, the sensor device comprising a device body with an interface wall having an inner surface and an outer surface,
- wherein the device body is pre-arranged to be mounted such that at least one portion of the outer surface of the interface wall is in contact with the liquid substance, to define therewith a reflection interface, and the inner surface of the interface wall is isolated from the liquid substance,
- wherein at least one detection arrangement is associated to the inner surface of the interface wall, the detection arrangement including an optical module which comprises at least one emitter and at least one receiver of a given optical radiation,
- wherein at least one first portion of the interface wall is made of a material suitable for propagation of the given optical radiation, the at least one emitter and the at least one receiver being optically coupled to the inner surface of the interface wall at said first portion,
- wherein said first portion of the interface wall is shaped to contribute to propagation of the given optical radiation by reflection at the reflection interface, from the at least one emitter to the at least one receiver, the given optical radiation from the at least one emitter being at least in part propagated through said first portion of the interface wall as far as the reflection interface, to be reflected by the reflection interface and further propagated through said first portion of the interface wall towards the at least one receiver, such that the given optical radiation is reflected at least in part by the reflection interface with an angle that is variable as a function of the at least one characteristic of the liquid substance,
- wherein the inner surface of the interface wall is shaped at said first portion to define a positioning site for the optical module, the positioning site including at least one projecting element defining a first inclined surface and a second inclined surface, the first inclined surface and the second inclined surface being inclined in opposite directions to identify therebetween an angle smaller than 90°, the at least one emitter facing the first inclined surface and the at least one receiver facing the second inclined surface, the at least one emitter and the at least one receiver each having a respective axis and being set such that a plane passing through the axis of the at least one emitter intersect a plane passing through the axis of the second receiver to form therebetween an angle greater than 90°,
- wherein the optical module includes a structure for support and electrical connection of the at least one emitter and the at least one receiver, which is configured as a part separate from the device body,
- wherein the positioning site includes a coupling element at which the structure for support and electrical connection is mechanically secured, the coupling element being defined at the at least one projecting element in a position intermediate to the first inclined surface and the second inclined surface,
- wherein the structure for support and electrical connection is at least partially elastically flexible, to enable the at least one emitter and the at least one receiver to vary a relative position thereof and with respect to the first inclined surface and the second inclined surface, respectively, when mechanically securing the structure for support and electrical connection to the coupling element,
- and wherein the structure for support and electrical connection includes a plurality of bodies made of electrically insulating material associated to one or more electrical-connection elements made at least in part of electrically conductive material, the one or more electrical-connection elements defining or integrating electrical conductors for electrical connection of the at least one emitter and the at least one receiver.