Analysis of ZnO Diaphragm for Acoustic Sensor Applications

In this study, the detection parameters of diaphragm-based fiber optic sensors (DFOS) to be used in acoustic detection applications were analyzed for a ZnO diaphragm. ZnO diaphragm was chosen due to its mechanical durability, high acoustic conductivity, and unique optical properties in the visible and near-infrared regions. The mechanical properties of the diaphragm are of great importance in improving the detection parameters of the sensor. However, when commercially produced diaphragms are used, it is not possible to alter the specified parameters. The geometric dimensions of the diaphragm, as much as its mechanical properties, also have a significant impact on sensor parameters such as sensitivity and bandwidth. Therefore, the analysis of the thickness and radius parameters of the diaphragm is crucial. For this purpose, simulation studies were conducted with different thickness and radius values of the ZnO diaphragm through static pressure and dynamic field analyses using Comsol Multiphysics software. Based on the simulation results, it was observed that the highest sensitivity was achieved with a ZnO diaphragm having a 2 mm radius and $20 \mu \mathrm{m}$ thickness at a frequency of 15 kHz. The analyses conducted will greatly facilitate the design of acoustic pressure sensors and optical microphones, as well as long-distance listening and partial discharge detection applications.