Piezoelectric-electromagnetic wearable harvester for energy harvesting and motion monitoring

This paper proposes a piezoelectric-electromagnetic wearable harvester (PEWH). The device is used to harvest the energy generated when the upper limb swings and can perform the function of motion monitoring. The main structure of PEWH consists of the piezoelectric power generation module and electromagnetic sensing module. Among them, the piezoelectric sheet in the piezoelectric module deforms and outputs electric energy, and the magnetic ball in the electromagnetic module moves to generate induced electromotive force to achieve sensing and energy supply. Through experimental testing, PEWH output performance is optimal when the spring wire diameter is 0.8 mm and the distance between the spring connector where the spring located and the position of the top of the shaft is 65 mm. At a vibration excitation frequency of 2 Hz, the device's output voltage reaches a peak-to-peak value of 57.84Vpp, accompanied by a maximum power of 115.52mW. A range of application experiments were conducted to confirm the output performance of the device, which can power 82 LEDs and the temperature and humidity sensor. The prototype can be worn on the arm to enable monitoring of the current movement status. PEWH can effectively capture the energy generated by human movement for self-powered and self-sensing motion detection.