In the last 10 years, a new class of materials has been developed and is being further improved nowadays: the class of self-healing materials. This category of bio-inspired materials is potentially capable of repairing structural or functional damage in different ways, increasing the material lifetime. Polymers are the most studied material class in the field. For a better design of this material,it would be of enormous importance to detect and quantify the invisible internal damage occurring inside a polymer in order to value the healing efficiency before the ultimate failure. However, most of the avail??able scientific literature focuses on macroscopic and optically detectable damage.