| Abstract Scope |
Aluminum is a lightweight electrical conductor. Although the conduction behavior is well-known, the dielectric (polarization) behavior is not. The polarization stems from the interaction of the free (valence) electrons with the atoms. It gives a voltage that impedes conduction. The resulting increase in the apparent resistivity degrades the conduction performance. In addition, the capacitance resulting from the polarization delays the signal propagation (RC time constant). The capacitance relates to the permittivity (a material property), which is high (54,800, 2 kHz). Although the resistance is not affected by bending, the capacitance is reduced by bending. Upon bending back to the original straight shape, the capacitance is approximately restored for a single bend with various radii of curvature, but it is only partially restored for multiple bends. Bending degrades the dielectric connectivity (dipole-dipole interaction). The capacitance increases monotonically and reversibly with increasing tensile stress (elastic regime), thereby allowing capacitance-based stress/strain self-sensing. |