Dynamic and stationary performance analysis of diaphragm based acoustic pressure sensor

Abstract

Pressure sensing and measurement are of utmost importance in many of the process industries and biomedical applications. The key element of the pressure sensor is diaphragm and the diaphragm design including shape and dimensions play a major role in sensitivity of pressure sensor irrespective of the type of sensor viz. capacitive, piezoresistive or piezoelectric sensor. The acoustic pressure sensors require the proper analysis of dynamic performance of the key element since the acoustic source is dynamic pressure. This paper presents the stationary and dynamic performance analysis of diaphragm for piezoelectric acoustic pressure sensor. The analysis has been done for better deflection of the diaphragm and optimized stress and strain in order to achieve maximum sensitivity. In design step, at first the diaphragm is analysed for natural frequency, modal frequencies and bandwidth of the structure since the piezoelectric resonant sensors can be used for sensing whenresonant frequency of the membrane is at least 3 to 5 times the highest applied frequency and for energy harvesting applications, when it is almost equal to the applied frequency.Hence, a comparison of shapes of diaphragm, with their fundamental and modal frequencies, deflection, and stress and strain is established. Further a resonant sensor structure is also analyzed for dynamic performance with cavity neck of different size to understand the importance of cavity neck in dynamic performance of the sensor. The circular diaphragm is found be the best choice from the point of view of maximum deflection and natural frequency and the structure with cavity neck has better bandwidth and deflection.