SPICE Modeling of Piezoelectric Energy Harvesting Device Utilizing Stress Influence

This paper presents a SPICE modeling of piezoelectric energy harvesting (PEH) device. We developed a wireless sensor system with the PEH device as an application. The PEH device is composed of a stainless cantilever, which has a piezoelectric film on the both side surface. The PEH device oscillates at resonance frequency when the tip of the cantilever is plucked. In SPICE simulator, an equation of motion of the cantilever is described to express a mass-spring-damper system by behavioral source. The stress of the piezoelectric film is computed by theoretical calculation and FEM analysis. Then, the stress, the piezoelectric coefficient d₃₁, and the area of the film surface formulate the electrical charge. The output voltage is given by the charge varying and an inherent capacitance. The comparison between an analysis and an experiment is represented. The output power of theoretical calculation and measurement are 310 μJ and 920 μJ respectively has occurred by plucking once. We also developed a prototype system of WSN node utilizing the PEH device. The system transmits the temperature data a few times by plucking once.