Abstract While wrist-worn electronics have great potential in a variety of areas, their applications are currently constrained by the limited working time of their electrochemical batteries. Harvesting energy from arm swinging motions provides a promising means to address this issue. In this work, we introduce a tiny repulsive magnetic spring to improve the performance of a wrist-worn inertial energy harvester. In contrast to conventional inertial rotational energy harvesters, the proposed device contains a repulsive magnetic spring that consists of two pairs of repulsive magnets. The existence of the magnetic spring lowers the potential energy well depth of the energy harvester by reducing the system’s stiffness, thereby enhancing power generation. An analytical model is built to predict the system performance and investigate the effects of the magnetic spring air gap. To validate this design, a prototype is constructed and tested using a bench-top excitation source that emulates the swinging motion of the human arm. The experiments show that, in the tested excitation frequency (0.7–1.3 Hz) and air gap (2.2–3.6 mm) ranges, the average output power is significantly enhanced by the magnetic spring and smaller air gap of magnets results in more improvement, which agrees well with the simulation results. With the requirement of a minimal amount of space, the magnetic spring helps the energy harvester achieve maximum output power of 151 μW with an air gap of 2.6 mm at 1.3 Hz. Additionally, a maximum power improvement of 425% for an air gap of 2.2 mm at 0.7 Hz is achieved compared with the conventional wrist-worn inertial energy harvester.

中文翻译：

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使用排斥磁性弹簧的增强型电磁腕戴式能量收集器

摘要 虽然腕戴式电子设备在各个领域具有巨大潜力，但其应用目前受到电化学电池工作时间有限的限制。从手臂摆动运动中获取能量为解决这个问题提供了一种很有前景的方法。在这项工作中，我们引入了一个微小的排斥磁性弹簧来提高腕戴式惯性能量收集器的性能。与传统的惯性旋转能量收集器相比，所提出的设备包含一个由两对排斥磁铁组成的排斥磁性弹簧。磁性弹簧的存在通过降低系统刚度来降低能量收集器的势能井深度，从而提高发电量。建立了一个分析模型来预测系统性能并研究磁性弹簧气隙的影响。为了验证此设计，我们使用模拟人类手臂摆动运动的台式激励源构建并测试了原型。实验表明，在测试的励磁频率（0.7-1.3 Hz）和气隙（2.2-3.6 mm）范围内，平均输出功率通过磁弹簧显着提高，磁体气隙更小导致更多改善，这与模拟结果非常吻合。在最小空间要求的情况下，磁性弹簧帮助能量收集器实现 151 μW 的最大输出功率，1.3 Hz 下的气隙为 2.6 mm。此外，对于 2.2 毫米的气隙，在 0 时的最大功率提高了 425%。