Investigation of self-oscillation piezoelectric energy harvesting mechanics for lower-limb motion

In this work, a lower-limb motion capturing piezoelectric energy harvester is demonstrated by integration of a 3D printing sliding block-rail mechanical structure with piezoelectric bimorph array. The unique sliding block-rail piezoelectric generator (S-PEG) is superior as converting three-dimensional (3D) lower-limb motion into one-dimensional (1D) linear sliding on the rail, which further activates the vibration of piezoelectric bimorphs for effective energy scavenging. The particularly designed mechanical structure enables to achieve a high-power output of 2.4mW at an extremely low operating frequency (0.75Hz) and reach to 160μC/s of the charging speed on a 1mF capacitor. Moreover, we demonstrate the feasibility of the S-PEG on the lower limb acts as an auxiliary battery to supply the wireless transmission modules for diversified applications. In addition, the capability of the S-PEG is displayed as a practical power source for wearable sensors of low-power Bluetooth temperature and humidity modules. Moving forward to the Internet of Things (IoT) framework, the S-PEG is able to become a promising candidate in the sustainable energy sources to further extend the lifetime of the wearable sensors.