Design, simulation and experimental validation of a breathing-driven electromagnetic energy harvester

• A wearable breathing-driven electromagnetic energy harvester (BEEH) is proposed. • The BEEH can generate power when the wearer is in the stationary position. • A frequency up-conversion mechanism enhances energy conversion efficiency . • In wearable experiments, the BEEH generates 2.919 W peak power and 83.4 mW average power. High output and the ability to provide continuous, reliable power under static conditions are essential for wearable energy harvesting systems. This paper presents a novel wearable breathing-driven electromagnetic energy harvester (BEEH) that converts the nonlinear expansion of the chest during breathing into electrical energy using a frequency up-conversion mechanism and a gear transmission system to drive high-speed rotor rotation. The design optimizes magnetic flux density and electromotive force by using high magnetic permeability annealed medium-carbon steel for the stator and rotor. Finite element analysis investigates the magnetic flux density distribution and calculates the open-circuit voltage, while experimental results validate the voltage calculation consistency. Experimental results show that at high speeds, the BEEH performs smoothly with minimal waveform distortion, while at reduced speeds, gear imperfections, vibrations, and increased magnetic forces lead to waveform distortion and the presence of third harmonics. Wearing experiments demonstrate that the BEEH generates a peak power of 1.059 W, an average power of 46.7 mW, and an effective output duration exceeding 0.4 s per breathing cycle. Overall, the BEEH offers potential for continuous and reliable energy harvesting, providing a sustainable power source for low-power wearable devices.