Hamid Jabbar

Sustainable micro-power circuit for piezoelectric energy harvesting tile

ABSTRACT Piezoelectric energy harvesting tiles are used for converting the power of pedestrian footsteps in to electricity and can be used at the micro- and milli-watt level for storage and powering electronics devices. This paper effectively combines the systems and techniques for developing a sustainable circuit with the self-starting and self-power functions to efficiently store energy and drive low power consumption electronic devices from the piezoelectric energy harvester tile. The main part of the system is 80% efficient impedance matching converter with the self-starting and battery-less operation. The presented circuit has an overall efficiency of 63% and can power a wireless sensor node to transmit the information wirelessly.

Design of piezoelectric energy harvester with additional springs for varying stiffness of module

Piezoelectric energy harvesting systems are mainly used in low-power circuits and small sensors because of the low output power. To enhance the output power, we developed a new method that overcomes the weaknesses of piezoelectric ceramic products. In a single degree-of-freedom system, a piezoelectric cantilever composed of a piezoelectric ceramic and a substrate beam was analyzed by modeling the equivalent mechanical system. Based on this equivalent system model, a new method was designed to determine the total stiffness of module, which consists of the stiffnesses of the substrate beam and additional springs. Additional springs were connected to the free end of the substrate beam. The total stiffness of module was varied by connecting additional springs having different stiffness constants to the substrate beam. The results showed that a high total stiffness achieved using an additional spring led to a higher natural frequency of the beam. Therefore, the matching impedance was decreased, and the output power was increased. The advantage of the method is that the stiffness of the entire system can be varied using a detachable spring, without changing the piezoelectric ceramic material. Using this proposed system, the stiffness for a specific external energy can be optimized, and the efficiency of piezoelectric energy harvesting can be increased.