MEMS硅微谐振式压力传感器压力检测元件的设计与研究

发布时间：2018-05-26 08:18

本文选题：压力传感器 + 四边固支薄膜　；参考：《电子科技大学》2017年硕士论文

【摘要】：硅微谐振式压力传感器是微传感器中重要的研究对象之一。其压力检测元件主要由一次敏感元件压力膜和二次敏感元件谐振梁组成。本文研究了一种梁膜间接连接式压力检测元件中压力膜的受力变形机理,该结构通过硅岛锚点将压力膜变形挠度转变为谐振梁的轴向拉伸位移,通过检测谐振梁在轴向力作用下固有频率的变化来间接测量外界压力。在外界载荷与谐振梁抗弯、抗拉刚度所引起的反作用力共同影响下压力膜中轴线挠度曲线不再呈抛物线状分布。目前,大部分文献主要研究压力检测元件中薄膜承受均布载荷作用时的变形情况,理论分析时往往忽略二次敏感元件对压力膜变形的影响,对叠加载荷下压力膜变形机理的研究大多采用有限元仿真,缺少理论依据。本文提出了一种计算压力膜在叠加载荷下变形挠度的解析模型,并借助此模型优化了压力检测元件各结构尺寸。给压力传感器设计人员提供了一种物理意义清晰、易于编程实现的高效分析手段,为传感器压力检测元件的结构设计提供了理论依据。本文对传感器压力检测元件的研究主要分为三部分:建立压力膜在均布载荷下的变形挠度解析模型。将压力膜变形视为四边固支矩形薄板的小挠度变形问题,推导出薄板变形的挠曲面表达式。在此基础上,将固支薄板等效为施加了边界分布力矩的简支薄板。通过将简支薄板在均布载荷、边界力矩作用下的变形挠度相叠加,得到固支矩形薄板在均布载荷下的变形挠度,理论计算结果与数值仿真结果得到了很好的相互验证。使用该解析模型分析了压力膜结构尺寸对其变形挠度的影响,以及均布载荷下薄膜的应力、内力分布情况,以此提出压力检测元件的结构优化方案;建立压力膜在叠加载荷下的变形挠度解析模型。在压力膜底部施加均布载荷的同时,于上方关于中心对称的矩形区域施加局部均匀载荷来模拟梁通过锚点施加于膜上的反作用力。同样,去掉固支约束后将简支薄板在上方局部均匀载荷、底部均布载荷以及边界分布力矩作用下的变形挠度相叠加,得到固支薄板在叠加载荷作用下的变形挠度,理论计算结果与仿真结果吻合程度较高。使用该模型分析了局部载荷对压力膜变形的影响,以此提出了硅岛锚点的结构优化方案;结合以上两种理论模型与有限元仿真,分析了压力检测元件中各部件间的相互影响,通过改变各部件结构尺寸,研究了压力膜变形挠度、谐振梁固有频率以及灵敏度的影响因素,并提出合理的结构优化方案以提高传感器性能。
[Abstract]:Silicon micro resonant pressure sensor is one of the important research objects in micro sensor. The pressure detecting element is mainly composed of the pressure film of the first sensitive element and the resonant beam of the second sensitive element. In this paper, the mechanism of mechanical deformation of pressure film in a kind of indirectly connected beam membrane pressure detection element is studied. The deformation deflection of pressure film is transformed into axial tensile displacement of resonant beam through silicon island anchor. The external pressure is indirectly measured by measuring the natural frequency of the resonant beam under axial force. Under the external load and the bending resistance of the resonant beam, the axial deflection curve of the pressure film is no longer parabolic due to the reaction force caused by the tensile stiffness. At present, most of the literatures mainly study the deformation of the film under uniform load in the pressure detection element, and the influence of the secondary sensitive element on the deformation of the pressure film is often ignored in the theoretical analysis. Finite element simulation is used to study the deformation mechanism of pressure film under superposition load, which is lack of theoretical basis. In this paper, an analytical model for calculating the deformation deflection of pressure film under superposition load is proposed, and the structural dimensions of the pressure detection element are optimized by the model. It provides a kind of high efficiency analysis method for the pressure sensor designer, which is clear in physical meaning and easy to realize by programming. It also provides the theoretical basis for the structure design of the pressure detection element of the sensor. In this paper, the research of the sensor pressure detection element is divided into three parts: the analytical model of the deformation deflection of the pressure film under uniform load is established. The deformation of pressure film is regarded as the small deflection of rectangular thin plate clamped on four sides, and the expression of deflection surface of thin plate is derived. On this basis, the clamped thin plate is equivalent to a simply supported thin plate with boundary distribution moment applied. By superposing the deformation deflection of simply supported thin plate under uniform load and boundary moment, the deformation deflection of clamped rectangular thin plate under uniform load is obtained. The results of theoretical calculation and numerical simulation are well verified. Using the analytical model, the influence of the structure size of the pressure film on its deformation deflection, the distribution of the stress and internal force of the film under uniform load is analyzed, and the structural optimization scheme of the pressure detection element is put forward. An analytical model of deformation deflection of pressure film under superposition load is established. At the same time, the uniformly distributed load is applied at the bottom of the pressure film, and the local uniform load is applied in the rectangular region of the center symmetry above to simulate the reaction force applied by the beam through the anchor point on the film. In the same way, when the clamping constraint is removed, the deformation deflection of the simply supported thin plate under the action of local uniform load at the top, uniform load at the bottom and the deformation deflection under the action of the boundary distributed moment are superimposed, and the deformation deflection of the clamped thin plate under the superposition load is obtained. The theoretical results are in good agreement with the simulation results. Using this model, the influence of local load on pressure film deformation is analyzed, and the structure optimization scheme of silicon island anchor point is put forward, and the interaction between the components in the pressure detection element is analyzed by combining the above two theoretical models and finite element simulation. By changing the structural dimensions of the components, the factors affecting the deformation deflection of the pressure film, the natural frequency of the resonant beam and the sensitivity are studied, and a reasonable structural optimization scheme is proposed to improve the performance of the sensor.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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