The effect of substrate to piezoelectric thickness ratio on performance of unimorph sensor

Abstract

This paper reports on our investigation of the influence of the piezoelectric to substrate thickness ratio on the output voltage and resonance frequency of a rectangular unimorph sensor. The results show that the sensitivity of the sensor is degraded for high values of thickness ratio beyond 1.0. Too small values of thickness ratio below 0.2 will result in low sensitivity due to high capacitance of the unimorph bender. In addition a comparison of aluminium and structural steel as substrates to PZT-5H piezoelectric material was also investigated. The findings are a useful guide to design engineers enabling the selection of appropriate material and geometry for a rectangular sensor depending on whether the primary design goal is large deflection, voltage or resonance frequency.