隧穿型石墨烯MEMS加速度计研究

隧穿型加速度计都有很高灵敏度，但是隧穿结局部电流过大，一般的隧穿结材料容易发生电迁移现象，导致隧穿型加速度计的灵敏度越来越低，大大降低了隧穿型加速度计的实际工作性能。本文利用石墨烯材料则可以有效的避免电迁移现象的产生，根据石墨烯的工艺特点，结合具体情况设计了六种石墨烯悬臂的结构形式。通过对质量块的尺寸和悬臂结构的设计，可以大大提高隧穿型石墨烯MEMS加速度计的灵敏度。 利用仿真软件COMSOL对石墨烯的六种结构形式进行设计与仿真分析，根据隧穿型加速度计的工作原理，提出了六种石墨烯悬臂的常用结构，分别是单边单悬臂、单边双悬臂、单边“S”型双悬臂、双边单悬臂、双边双悬臂、双边“S”型双悬臂。石墨烯悬臂的模态进行了较为详细的分析，得出了六种石墨烯悬臂的前六阶特征频率与振型图。 对所设计的六种石墨烯悬臂的弧长随惯性力作用下的变化进行仿真。由于石墨烯悬臂主要是用来感应加速度变化的，因此需要先研究石墨烯悬臂与惯性力对应关系。本文仿真出了石墨烯悬臂随惯性力的弧长变化情况。单边悬臂和双边悬臂不管在弧长的变化形式，还是在位移量的变化程度上都有各自的特点，但是单纯的石墨烯悬臂对加速度的敏感程度不是很高。因此本文特地加入了石墨烯悬臂与金材料的质量块结合后的情况分析，通过仿真结果可以发现质量块可以大幅提高加速度计的灵敏度。 对石墨烯悬臂与驱动电压的影响关系进行研究。我发现石墨烯材料对驱动电压非常敏感，很小的电压都可以导致石墨烯很大的形变，石墨烯悬臂实际工作情况时可以抬高石墨烯悬臂与驱动电极之间的距离。对所得的仿真结果进行了对应的拟合分析，得出了一些经验公式的参数。 对加速度计进行固体力学和静电场的多物理场耦合分析。由于加速度计实际工作环境是惯性力与驱动电压的耦合作用，所以本文对加速度进行了固体力学和静电场的多物理耦合仿真分析并结合实验室已有的设备设计了加速度计的测试平台，并且为所设计的测试平台编写了对应的信号读取代码。

The tunneling accelerometer has high sensitivity, but the tunneling terminal current is too large, and the general tunneling junction material is prone to electrical migration, which leads to the tunneling accelerometer sensitivity becoming lower and lower, which greatly reduces the actual working performance of the tunneling accelerometer. In this paper, graphene materials can effectively avoid the phenomenon of electric migration, according to the characteristics of graphene technology, combined with six specific design of graphene cantilever structure.By designing the size of the mass block and cantilever structure, the sensitivity of the tunneling graphene mems accelerometer can be greatly improved.Based on the principle comsol tunneling accelerometer, six kinds of common structures of graphene cantilever are proposed, unilateral single cantilever, unilateral double cantilever, unilateral "s" double cantilever, these structures are bilateral single cantilever, bilateral double cantilever, bilateral" s" double cantilever. The modes of the graphene cantilever are analyzed in detail, and the first six order characteristic frequencies and diagram of six graphene cantilever are obtained. The arc length variation of the designed six graphene cantilever with inertial force is simulated. It is necessary to study the relationship between the graphene cantilever and the inertial force, because the graphene cantilever is mainly used to induce the acceleration change. In this paper, the variation of the cantilever length of graphene with inertial force is simulated. The single-sided cantilever and the bilateral cantilever have their own characteristics in the variation of arc length and displacement, but the sensitivity of the simple graphene cantilever to acceleration is not very high. Therefore, this paper specially added the graphene cantilever and gold material mass block after the situation analysis, through the simulation results can be found that the mass block can greatly improve the sensitivity of the accelerometer. The relationship between the graphene cantilever and the driving voltage was investigated. I found that the graphene material is very sensitive to the driving voltage, and very small voltage can lead to a large deformation of graphene the distance between the graphene cantilever and the driving electrode can be raised when the graphene cantilever actually works. The corresponding fitting analysis of the simulation results is carried out, and the parameters of some empirical formulas are obtained. The accelerometer was subjected to multi-physical field coupling analysis of solid mechanics and electrostatic field. In this paper, the multi-physical coupling simulation analysis of solid mechanics and electrostatic field is carried out, and the test platform of accelerometer is designed in combination with the existing equipment in the laboratory, and the corresponding signal reading code is written for the designed test platform. Because the actual working environment of the accelerometer is the coupling of inertial force and driving voltage.