Frequency Up-Conversion Hybrid Energy Harvester Combining Piezoelectric and Electromagnetic Transduction Mechanisms

A hybrid energy harvester with frequency up-conversion structures is proposed. The harvester achieves a high power output by utilizing both piezoelectric and electromagnetic transduction mechanisms. The harvester comprises a flexible substrate and two (internal and external) cantilevers. The internal and external cantilevers used for piezoelectric and electromagnetic conversion, respectively, are arranged such that the piezoelectric internal cantilever can vibrate with a large displacement to produce high output power. We use a frequency up-conversion method to convert the bending of the harvester into the vibration of the structure so that the harvester can generate energy even from the mechanical motion with an extremely low frequency. Two harvester configurations are investigated to validate the effect of the relative positions of the coil and magnet on the output voltage of the harvester. The maximum power output of the hybrid harvester is 7.38 mW, with outputs of 1.35 and 6.03 mW for piezoelectric and electromagnetic conversion, respectively.