Matching the impedance of ionic polymer metal composites for energy harvesting

In this note, we investigate the possibility of matching the impedance of ionic polymer metal composites (IPMCs) to enhance energy harvesting from bending deformations. We focus on underwater quasi-static post-buckling of patterned IPMCs for different excitation frequencies. We consider a total of 14 samples with a single or two secondary plating layers to garner statistical evidence in favor of impedance matching, for a wide range of IPMC electrical properties. Impedance matching is compared to the classical use of optimized resistive loads. The shunting impedances are designed on the basis of an experimentally-validated physics-based model of IPMC chemo-electro-mechanical behavior. Our results demonstrate that impedance matching significantly benefits IPMC energy harvesting, with the surface resistance playing a key role on the extent of such improvement. Specifically, we find that samples with highly conductive electrodes tend to display a lower equivalent resistance and thus benefit the most from impedance matching.