低温环境下MEMS微构件的动态特性及测试系统

Dynamic testing of MEMS micro-structure and its measurement system at low temperatures

研究了微机电系统(MEMS)微构件的谐振频率等动态特性在低温环境下的变化规律,从理论上分析了改变环境温度对微悬臂梁谐振频率的影响,并对低温环境下微构件的动态特性测试技术进行了研究。研制了低温环境下MEMS动态特性测试系统,采用半导体冷阱实现低温环境,利用压电陶瓷作为底座激励装置的驱动源,通过底座的冲击激励,使微悬臂梁处于自由衰减振动状态,使用激光多普勒测振仪对微悬臂梁的振动响应进行检测,从而获得微悬臂梁的谐振频率。利用研制的测试系统,在-50℃～室温的环境下对单晶硅微悬臂的谐振频率进行了测试,结果表明,随着温度的降低,微悬臂梁的谐振频率略有增大,其谐振频率的温度变化率约为-0.263 Hz/K,与理论分析的结果基本一致。该测试装置能够有效地完成在-50℃～室温环境下微构件的动态特性测试。

To investigate the dynamic characteristics of micro-structure in a Micro-electro-mechanical System（MEMS） at a low temperature environment, a theoretical model was established and the effect of environmental temperatures on the resonant frequency of a micro-cantilever was researched. Then, a dynamic testing system for MEMS at low temperature was developed. In testing, a thermoelectric cooling refrigerator was utilized to generate the low temperature environment and the piezoelectric ceramic was used as the driving source to establish the base excitation device. Through the base impact excitation, the resonance frequencies were obtained by analyzing the impulse response signals and the frequency response of micro-cantilever was tested by using a laser Doppler vibrometer. The dynamic testing experiments for the silicon micro-cantilever were carried out from -50 ℃ to room tempera- ture. Obtained results show that the resonance frequency slightly increases with the decreasing ternperature, and it is consistent with that of the theoretical analysis. The temperature dependency of fre quency is about -0. 263 Hz/K,which is a little smaller than that of the theoretical results. The meas urement device is very effective to carry out dynamic testing of microstructures from -50 ℃ to room tempera ture.