Yuan Ning-Hsiu, Chen Chih-Chia, Fuh Yiin-Kuen, Li Tomi T
Department of Mechanical Engineering, National Central University, Taoyuan City 320317, Taiwan.
Materials (Basel). 2023 Mar 6;16(5):2129. doi: 10.3390/ma16052129.
This paper reports two piezoelectric materials of lead zirconium titanate (PZT) and aluminum nitride (AlN) used to simulate microelectromechanical system (MEMS) speakers, which inevitably suffered deflections as induced via the stress gradient during the fabrication processes. The main issue is the vibrated deflection from the diaphragm that influences the sound pressure level (SPL) of MEMS speakers. To comprehend the correlation between the geometry of the diaphragm and vibration deflection in cantilevers with the same condition of activated voltage and frequency, we compared four types of geometries of cantilevers including square, hexagon, octagon, and decagon in triangular membranes with unimorphic and bimorphic composition by utilizing finite element method (FEM) for physical and structural analyses. The size of different geometric speakers did not exceed 10.39 mm; the simulation results reveal that under the same condition of activated voltage, the associated acoustic performance, such as SPL for AlN, is in good comparison with the simulation results of the published literature. These FEM simulation results of different types of cantilever geometries provide a methodology design toward practical applications of piezoelectric MEMS speakers in the acoustic performance of stress gradient-induced deflection in triangular bimorphic membranes.
本文报道了两种用于模拟微机电系统（MEMS）扬声器的压电材料，即锆钛酸铅（PZT）和氮化铝（AlN），它们在制造过程中不可避免地会因应力梯度而产生挠曲。主要问题是来自振膜的振动挠曲会影响MEMS扬声器的声压级（SPL）。为了理解在相同激活电压和频率条件下，悬臂梁中振膜几何形状与振动挠曲之间的相关性，我们通过利用有限元方法（FEM）进行物理和结构分析，比较了三角形膜中具有单压电层和双压电层组成的四种悬臂梁几何形状，包括正方形、六边形、八边形和十边形。不同几何形状扬声器的尺寸不超过10.39毫米；模拟结果表明，在相同激活电压条件下，氮化铝等相关声学性能与已发表文献的模拟结果具有良好的可比性。这些不同类型悬臂梁几何形状的有限元模拟结果为压电MEMS扬声器在三角形双压电层膜中应力梯度引起的挠曲声学性能方面的实际应用提供了一种方法设计。
