Efficiency improvement of energy harvester at higher frequencies

This research suggests employing electrode segmentation in order to avoid charge cancellation in the piezoelectric layers of harvester, which occurs, if strain nodes of vibrating harvester are covered by continuous electrodes. Two types of piezoelectric energy harvester prototypes were produced from piezoelectric plate, epoxy bonded to stainless steel substrate for experimental investigations. The first (reference) harvester prototype posses no electrode segmentation, while electrodes covering piezoelectric material of second harvester were segmented. Segmentation of the second harvester was configured for its operation at the second resonant frequency – i.e., performed so, that the electrodes of piezoelectric layer are not covering strain node of the second vibration mode. Experimental results revealed that segmented harvester prototype posses efficiency advantage as compared to the non-segmented counterpart – adding voltages, generated at each segment would result from 16 % to 60 % increase of maximum generated voltage. Also conception, that using stopper, placed at appropriate position, energy harvesting process could be stabilized, i.e. bandwidth of operating frequency could be increased