A high-performance mini-generator with average power of 2 W for human motion energy harvesting and wearable electronics applications

Abstract

The sustainability of power supply for mobile electronic devices is a problem that needs to be solved urgently. The energy from human motion is an optimal solution for this problem. As for the traditional energy harvesters based on electromagnetic, triboelectric, and piezoelectric induction, energy management is the largest challenge because of the low conversion efficiency and output power. In this paper, a high-efficiency and high-power energy harvester (EPEH) is presented based on the intersecting beam array structure. It can effectively harvest the pressure energy of humans under the soles at the states of walking, running, and weight-bearing walking. The EPEH does not impair the flexibility of humans compared with joint energy harvesters. The intersecting beam array structure is key component, which can magnify the compression distance in the vertical direction of 3.4 times in the horizontal direction, facilitating maximum energy harvesting within a limited height. On the other hand, the design of rolling friction structure can effectively reduce energy loss and improve energy conversion efficiency. The result shows that the maximum average output power can reach 2 W at 7 km/h. Because of the high output power, the energy management circuits and voltage regulator circuits can be derived and stable work, the energy harvested by the EPEH can be stored in the lithium battery (3.7 V, 50 mAh). Furthermore, the generated energy could supply mobile phones, smart watches, light bulbs, flashlights, children's anti-lost devices, and so on. Through the energy management circuit and voltage regulator circuit (1.5 V and 5 V), the energy conversion efficiency of the device can reach 65.2 % at a compression velocity of 2500 mm/min and a frequency of 1.25 Hz. It is of great significance for the practical application of wearable energy harvesting technology and has multiple application prospects.