Design and Experimental Studies of a Heel-Embedded Energy Harvester for Self-Powered Wearable Electronics

Abstract

Abstract Recent decades have witnessed a booming increase in the number of wearable electronic devices. However, these devices cannot work for a very long time due to the limited lifespan of internal electrochemical batteries. In this article, we present a novel wearable electromagnetic energy harvester (EMEH) embedded into a heel of a shoe to collect the kinetic energy from human motion to tackle the above problem. The harvester is mainly composed of a pedal, four springs, a cantilever, and an electromagnetic energy transduction unit. In this design, we adopt a cantilever and a two-stage displacement amplification mechanism to convert up the frequency of the excitation, magnify the input displacement from the foot, and take advantage of an alternating magnet pole arrangement to get abrupt changes in the magnetic flux density (MFD). An electromagnetic dynamic model was established to simulate the output power of the harvester. Besides, we fabricated a prototype to examine the output performance of the harvester. The results prove that the cantilever can effectively convert low-frequency human running motions into high-frequency oscillations, which crucially contributes to the high performance of the harvester. As a portable energy conversion source, the proposed harvester can be of great significance in promoting the development of wearable self-powered electronic devices.