磁悬浮式电磁-摩擦复合生物机械能量采集器

能量采集技术已经成为智能终端领域的一项关键技术,关于人体机械能采集方式也有大量的研究.针对人体机械能采集的应用需求,本文提出一种基于磁悬浮结构的电磁-摩擦复合式能量采集器.该能量采集器以磁悬浮结构作为核心部件,具有结构简单、感应灵敏、输出功率高的优点.在10 MΩ的外接负载时,两组摩擦发电单元输出功率分别为0.12 mW和0.13 mW;在1kΩ外接负载时,两组电磁发电单元的输出功率分别为36 mW和38 mW.复合能量采集器通过电容储能后,电容器可以输出8 V电压,且输出信号为持续的直流信号,可以为计步器提供持续的能量供给,支撑计步器正常工作.设计的复合能量采集器对于可穿戴电子设备自供电工作模式的实现具有重要意义.

Electromagnetic-triboeletric hybridized generator based on magnetic levitation for scavenging biomechanical energy

The popularity of various portable electronics and biological health monitoring devices, such as pedometers, pulse oximeters, mobile telephones, wearable watches, has greatly changed our lifestyles and brought significant convenience to us. Energy harvesting has been a key technology for the self-powered mobile terminals, because there are many defects such as limited lifetime, large size, low energy density and environmentally unfriendly feature for the traditional chemical batteries. Lots of devices used for the energy harvesting of the human movement have been reported. However, some problems such as poor efficiency, low output power and low sensitivity need further studying.
In this work, we demonstrate a novel magnetically levitated electromagnetic-triboelectric generator. The device size is φ4.8 cm×2.4 cm, and its weight is 80 g. The device uses the magnetically levitation structure as the core components, and the structure contains four magnets to form a magnetic array, in which three cylindrical magnets are placed around a bigger magnet. And two coils with polyvinyl-acetal enameled copper wires of 70 μm areplaced at the top and bottom of the device, respectively. Then two silica gel thin films with inverted tetrahedron patterned on the surface are integrated inside the structure. Then, we analyze the motion feature with the Maxwell simulation software, and discuss output characteristics of the two energy harvest units theoretically. The device possesses a high sensitivity, wide frequency response and high output performance. The dynamic response characteristics are analyzed in this paper.
The frequency response range of the device is from 2 Hz to 20 Hz. The wider frequency response means that it can harvest more energy from complicated external environment. Furthermore, we analyze the output signal at low frequency, which has more than one wave crest after an environment perturbation. The triboelectric units can deliver peak output voltages of 70 V and 71 V, respectively, and the electromagnetic units each can deliver a peak output voltage of 10 V. In addition, the triboelectric units can produce peak output powers of 0.12 mW and 0.13 mW, respectively, under a loading resistance of 10 MΩ, while the electromagnetic units produce peak output powers of 36 mW and 38 mW, respectively, under a loading resistance of 1 kΩ. We discuss the energy output and energy conversion efficiency of the device, which are 750.89 μJ and 18%, respectively. Then we use the hybridized generator to charge a capacitor of 33 μF, the output voltage of which can reach 8 V in 2 seconds. Furthermore, the hybridized generator can power a pedometer continuously, which can work steadily and display movement data. This work has a significant step toward human mechanical energy harvesting and potential application in self-powered wearable devices.