A flexible, self-healing sensor skin

A skin structure exhibiting flexibility, self-healing and damage sensing has been designed, fabricated and tested. The skin is fabricated on a substrate of copper-clad polyimide sheets in a layer-by-layer technique using polyimide sheets and an ultraviolet (UV)-curable epoxy. The UV-curable epoxy is used as both a structural adhesive and as the self-healing fill material. The skin structure is integrated with an array of LC circuits, where each circuit is characterized by a unique resonant frequency. If the skin is damaged, the UV-curable epoxy is released and is cured by ambient sunlight. Further, damage affects one or more of the LC circuits, altering its resonant frequency. An integrated antenna coil is used to detect and locate the damaged portion of the skin. A proof-of-concept skin is presented which includes a 2 x 2 array of LC circuits. Tests indicate good performance with respect to self-healing of the skin and fault isolation.