High-Performance Millimeter Scale Electromagnetic Generator

Electromagnetic generator (EMG) is a promising alternative solution to traditional chemical batteries due to its distinct advantages such as high reliability, high power density, long lifetime, and wide applicability to extreme environments. Recently, the EMG has been developed with magnetic levitation structure and magnetic flux concentrator (MFC) methods to increase the electrical output performance by introducing magnetic repulsive force and concentrating magnetic field. However, as the EMG device scales down in dimension, the undesirable interaction between magnets and insufficient area severely limits the performance of the MFC. Here, a high-performance millimeter scale electromagnetic generator (mmEMG) is devised by the MFC films on both ends of coils inducing highly concentrated magnetic flux. The effect of the MFC is investigated depending on various structural parameters by simulation, and confirmed experimentally. Also, the influence of magnetic properties on the MFC by characterization with different soft magnetic materials is studied. With this process, the mmEMG is optimized with the MFC device showing 4 mWcm⁻³ despite its light weight and tiny size, a 5.6-fold improvement in terms of electrical output. Finally, powering commercial electronics are successfully demonstrated and constructed a self-powered force feedback-based gripper control system by integrating the device with the soft gripper via machine learning.