Integrity-Sensing Based on Surface Roughness of Copper Conductors for Future Use in Natural Fiber Composites

Copper shows the remarkable behavior of the formation of surface roughness under mechanical strain, which creates the opportunity for its use as a sensing element. A copper-based sensor, which is intended for integration into natural fiber composites, can provide information about the remaining service life of the composite material and, thus, monitor the component's structural integrity. In this letter, proof is provided that the mechanical strains tension/compression, bending and torsion generate surface roughness on copper conductors. To verify this thesis, roughness is generated in different standardized test setups. Measurements of the root mean square height S q verify that all relevant forms of mechanical forces lead to increased surface roughness. Furthermore, two methods are presented, which allow us to vary the sensitivity of the copper conductor to mechanical stress. The changes in mechanical properties are visualized with a stress-strain diagram. By providing evidence for the chain of reasoning, this article gives a qualitative proof for the feasibility of a "line sensor."