基于材料热失配的MEMS准零刚度低频振动传感器研究

MEMS quasi-zero-stiffness low-frequency vibration sensor with the ability to sense Nano-g vibration can meet the requirements of major national construction projects, national defense construction and frontier science exploration. In this project, under the action of thermal stress caused by the mismatch of materials thermal expansion coefficient, the clamped beam will buckle and show negative stiffness characteristic. The buckled beam can reduce the total stiffness of the sensor nearly to zero and thus forms a quasi-zero-stiffness system. The stiffness of buckled beam is determined by thermal stress, therefore the total stiffness of the sensor can be adjusted and compensated by changing the operating temperature. This technology is expected to compensate stiffness deviation caused by machining and assembly tolerance for the first time. This work as a fundamental and frontier research is significant for promoting the precision of MEMS low-frequency vibration sensor.

MEMS准零刚度低频振动传感器可检测低至Nano-g量级的振动信号，在国家重大工程建设、国防建设和科学前沿探索等方面有着重要的应用需求。本项目拟利用材料热失配产生的应力使固支梁屈曲并呈现负刚度特性，进而将传感器总刚度降低至零附近，以形成准零刚度低频振动传感器。由于屈曲梁的刚度状态与热应力相关，因此本项目可通过控制传感器的工作温度来对系统刚度进行动态调节和精确补偿，从而解决现有技术无法对由工艺误差和装配误差造成的刚度偏差进行补偿的问题。该工作对突破现有MEMS低频振动传感器的精度极限有重要的研究意义和价值，是一项基础性、前沿性极强的科学研究。

非谐振式电容传感器的性能与其灵敏度正相关，降低固支梁刚度是提升非谐振式电容传感器灵敏度有效技术途径。项目针对振动传感器等非谐振式电容传感器灵敏度局限的问题，提出基于静电装配的刚度调节技术。静电装配使固支梁上产生的轴向力，引起固支梁刚度的变化，使其呈现非线性特性。因此静电装配实现了固支梁刚度的精确调节，解决了现有技术无法对工艺误差进行补偿的问题。测试结果表明基于静电装配的刚度调节技术的振动计刚度降低40%以上，灵敏度提升了70%以上。该工作证明基于静电装配的刚度调节技术对非谐振式电容传感器灵敏度提升明显，可用于多种MEMS电容式传感器设计。