A Compact Human-Powered Energy Harvesting System

A fully functional, self-sufficient body-worn energy harvesting system is presented in this paper. The system is designed for passively capturing energy from human motion, with the long-term vision of supplying power to portable, wearable, or even implanted electronic devices. Compared with state-of-the-art vibrational systems, the system requires no external power supplies and can bootstrap from zero-state-of-charge to generate electrical energy from walking, jogging, and cycling; convert the induced AC voltage to DC voltage; and then boost and regulate the DC voltage to charge a Li-ion-polymer battery. Measurements show that at open-load the system turns on when the input is above 1 V and turns off when the input drops below about 600 mV with no measurable standby power consumption. Tested under normal human activities (walking, jogging, and cycling) when worn on different parts oze body, the 70 cm system is shown to charge a 3.7 V rechargeable battery at charge rates ranging from 33 μW to 234 μW.