No abstract

This paper introduces the design and characterization of a double-stage energy harvesting floor tile that uses a piezoelectric cantilever to generate electricity from human footsteps. A frequency up-conversion principle, in the form of an overshooting piezoelectric cantilever, plucked with a proof mass is utilized to increase energy conversion efficiency. The overshoot of the proof mass is implemented by a mechanical impact between a moving cover plate and a stopper to prevent damage to the plucked piezoelectric element. In an experiment, the piezoelectric cantilever of a floor tile prototype was excited by a pneumatic actuator that simulated human footsteps. The key parameters affecting the electrical power and energy outputs were investigated by actuating the prototype with a few kinds of excitation input. It was found that, when actuated by a single simulated footstep, the prototype was able to produce electrical power and energy in two stages. The cantilever resonated at a frequency of 14.08 Hz. The output electricity was directly proportional to the acceleration of the moving cover plate and the gap between the cover plate and the stopper. An average power of 0.82 mW and a total energy of 2.40 mJ were obtained at an acceleration of 0.93 g and a gap of 4 mm. The prototype had a simple structure and was able to operate over a wide range of frequencies.

No abstract

In recent years, wireless sensor network is used in a variety of applications and highly required. These wireless sensor network is powered by the battery with limit energy. Therefore, the integration of energy harvester and wireless sensor network has received more attention because it can prolong the lifetime of battery in a sensor node. The focus of this paper is to design the energy harvesting device from machine vibrations for wireless sensor node, which the amplitude and frequency of vibration source were contributed on the design. The structure of energy harvesting devices is a resonant type piezoelectric energy harvester with a proof mass at the tip of the beam for tuning its resonant frequency. The proposed piezoelectric energy harvesters were then designed and analyzed by using Finite Element Method (FEM) to optimize the natural frequency of the harvester. Then, the prototype energy harvesters were made and mounted to a vibration source for experiments. The result reveals that the optimal piezoelectric energy harvester can generate the output power of 82.29 µW at the resonant frequency of 50 Hz.

No abstract