Optimization of a human-limb driven, frequency up-converting electromagnetic energy harvester for power enhancement

We present an optimized electro-magnetic energy harvester (EMEH) that generates significant power from the motion of human limbs, to be used in hand-held and wearable smart device applications. The proposed EMEH is designed to up-convert the vibration of human limb-motion to high-frequency by mechanical impact of a freely movable ball on two optimized frequency up-converted generators. Each generator comprises a compact and reliable helical compression spring. The generators have been optimized through the design parameters such as frequency, spring stiffness, mechanical and electrical damping, to minimize the power loss. The device offers 333μWcm^-3 average power density (a maximum 2.15mW of average power while two generators are connected in series) which is considerably higher than the current state-of-the-art devices.