Fig. 1. Schematic showing self-healing principle and fabrication process.

(A) Image of a self-healing circuit demonstrating its autonomous recovery upon complete damage (damage width, 3 mm). The scheme at the top shows the working principle of the self-healing process. The printed self-healing trace consists of aligned NMPs, which produce a net magnetic field along the length of the trace, thus making the trace behave as a bar magnet (left image + scheme). When the trace is severed, the two pieces behave as individual bar magnets, with opposite poles attracting each other (middle image + scheme). The strong magnetic attraction between the two severed pieces forces them to move toward each other to regain the mechanical and electrical connectivity (right image + scheme). (B) Pictorial representation of the printing process for realizing the self-healing trace. The scheme illustrates the initial random orientation of the NMPs within the printed trace and gradual alignment.