Alternatively, the spring 70 may be a planar spring, such as an ortho-planar spring. It may also be of plastic material, such as of a thermoformable plastic film. In case of planar spring, the functional multilayer structure 20 may, for example, comprise a hole, recess, or cavity into which the planar spring can extend when the movable member 40 is being moved towards the structure 20. Alternatively, the planar spring may extend into such hole, recess, or cavity in the movable member 40, or there may be such holes, recesses, or cavities in both of the structure 20 and the movable member 40. Still alternatively, a support frame, such as a support ring or the like, may be utilized for providing space for the planar spring to move.
The spring 70 may, when being compressed, slide on the surface of the structure 20 and the movable member 40. On the other hand,