Structural health monitoring is increasingly required in the field of infrastructure, both because standards expressly require it and because current guidelines for bridge maintenance and monitoring refer to it for existing works. Indeed, a perspective approach to functional materials and structures pushes toward monitoring systems effective since the construction stages and up to its end of life. Monitoring systems are divided into two main groups: those embedded into the structure and those attached superficially to the structure. The first one, being inside the structure, are better protected, but difficult to replace in case of damage; the latter are subject to external environmental aggression, but easy to replace.