A Novel Device to Harvest Kinetic Energy from Human Body Motion

Abstract

Mobile electronic devices such as cellular phones, remote controllers, PDAs, and etc, are everywhere. Most of these devices, if not all, are powered by batteries. While the battery is effective, its capacity and life is limited causing various concerns. Therefore, sustainable power source for mobile electronics is important. This paper presents a new energy harvester to harvest the human kinetic energy and converts it to electricity for mobile electronic devices. The proposed design consists of a stator and an eccentric mass made of permanent magnet as the rotor. It can generate magnetic field and hence, the electricity from the human body motion. In order to accommodate the motions in both horizontal and vertical planes, in the proposed design, a torsion spring is added onto the rotor providing an initial position such that the accelerations in both directions can be effectively harvested. Moreover, the harvester can be made as a bangle or integrated into a mechanical watch. With 40 mm in diameter and 20 g in weight, the proposed device could generate about 30 mW.