A wearable energy harvester unit using piezoelectric–electromagnetic hybrid technique

Wearable sensor electronics require a sustainable electrical power supply to operate. Energy harvesting techniques can be used to convert available nonelectrical energy sources into electrical energy. This paper presents WE-Harvest system, which is a new wearable energy harvesting system that combines piezoelectric and electromagnetic energy harvesters in one unit to generate a combined electrical energy source. Piezoelectric transducers are used to obtain sufficient regulated output voltages while electromagnetic is employed for its high power generation capability. Regular human body motions provide input vibrations for the proposed energy harvester unit. Several conditioning circuit topologies are proposed to efficiently extract energy from the two sources. The experimental results demonstrate that the combined topology enhances the power generation efficiency as well as enables stable output DC voltages. The dependence of energy harvester output on the load and input frequency has also been investigated.