Linearity Improvement for Cantilever Based Piezoelectric by Using Resonant Shifting Method

Abstract

Piezoelectric cantilever as a resonant structure can be used both as a sensor as well as an energy harvester. When excited at a frequency near to its resonant, maximum electrical power is generated, therefore it functions as a micro-power generator. When excited to a frequency which is far from the range of the resonant, the voltage signal generated is comparatively linear at the non-resonant region and proportional to the acceleration level; therefore, in this region of frequency it functions as a sensor. This paper demonstrates the potential of the piezoelectric cantilever to be altered in a way to act as a battery-less acceleration sensor which is independent to the frequency. The frequency response of the piezoelectric cantilever is characterized by altering the cantilever length with the intention to shift the resonant frequency region of the piezoelectric cantilevers higher region so it will not influence the output response of the piezoelectric cantilever. The resonant frequency of cantilever at normal condition is 300Hz, increased to 320Hz after length reduction of 0.7cm, increased to 400Hz after length reduction of 1.0cm, 500Hz for reduction of 1.2cm, and lastly 780Hz for reduction of 1.5cm. After length reduction of 1.5cm, the linear response of the piezoelectric cantilever improved from 90% error deviation to 15% error deviation, which is a major improvement in the linearity of the piezoelectric cantilever’s output.