Design and fabrication of piezoceramic bimorph vibration sensors

A bimorph-type piezoceramic vibration sensor is developed that can make up for the shortcomings of current mass loaded type sensors, such as high price, low sensitivity, and complex structures. For the design, in conjunction with piezoelectric constitutive equations, we derive full analytic response equations of the bimorph sensor to external forces. As the external forces, two representative cases are considered, step and sinusoidal excitation. Based on the results, actual sensors are fabricated and tested for verification of the theoretical results. Thermal stability of the bimorph structure is also checked through experiments. Further, a comparison of performance of the developed sensor is made with that of a commercial reference sensor so that quantitative evaluation of its sensitivity can be made. The sensor developed in this work shows excellent sensitivity and thermal stability in addition to the merits of simple structure and ease of fabrication. The design procedure with the sensor voltage response equations derived in this paper can be applied to develop piezoelectric bimorph sensors to meet any practical specifications.