Optimisation of a forced multi-beam piezoelectric energy harvester

A high-power multi-beam piezoelectric energy harvesting device is designed to meet the demands of the emerging technologies in Body Sensors Networks (BSNs), Wireless Sensors Networks (WSNs), the Internet of Things (IoT) and the Industrial Internet of Things (IIoTs). The proposed device utilises a plucking mechanism to excite the beams, organised in a comb-like structure. The harvester is presented in different length configurations and its performance is optimised to deliver the highest power under a given set of parameter values, constraints, and excitation characteristics. The unique feature of the device is that it can be tuned to any given frequency, although it demonstrates its superior performance in the frequency range of 2-50 Hz, delivering hundreds of mW. The device optimisation is conducted using a harmonic excitation, a harmonic excitation with random phase modulations, experimental vibration data collected using an internal combustion engine, and numerical data from simulations of out-of-plane oscillations of wind turbine blades. The paper proposes solutions to a number of challenges specific for multi-beam structures that have never been addressed before. It is demonstrated for the first time that the proposed harvester is able to meet the demands of relevant sensing applications.