Research On The Characteristics Of The Excitation Device For Testing The Dynamic Characteristics Of MEMS Microstructure

Dynamic characteristics testing technology of MEMS microstructure, mainly includes three aspects: vibration excitation, vibration testing, and modal analysis, in which vibration excitation is the basis to realize dynamic characteristics test. By researching on literatures, the dissertation summarized most kinds of excitation technology used in dynamic characteristics testing of microstructures currently. After analysis and comparison, PZT based excitation method was chosen as the research object. The dissertation analyzed theoretically the dynamic characteristics, including the bandwidth the device could excite and the resonance frequencies of the device, of PZT based excitation device which excited by step voltage. It proved theoretically the feasibility of testing the dynamic characteristics of microstructures using PZT based excitation device. The performance of driving power source greatly affects the dynamic characteristics of the Piezoelectricity base excitation device. A driving power source is Designed and fabricated for PZT based excitation device, which can actualize automatic control or manual control and protect itself from destroying as a result of improper control. The rise time of the power source excited by the step voltage is tested, and the result indicates that the driving power source can satisfy basically the demand for driving the excitation device. A system for testing the dynamic characteristics of PZT based excitation device is designed and built. The system utilizes the laser-detection circuit to test the periodical light intensity on silicon light diode, which reflects the dynamic characteristics of the excitation device. The structure of the system which is capable of detecting amplitude of micron level and frequency up to several MHz is simple. With the testing system, the dynamic characteristics of the PZT are tested respectively on the condition of free upper interface, no pretightening load and pretightening load existing. The results are basically in consistent with theoretical analysis, and proof the accuracy of theoretical analysis and the reliability of the testing system. Some conclusions can be derived: Choosing materials with low acoustic impedance as the upper cover board of the PZT can broaden the excitation bandwidth; Applying proper pretightening force on the PZT can also broaden the excitation bandwidth; Changing the structure of the excitation device can change the resonance frequency of the PZT. The typical micro-beam-mass structures were tested with the excitation device which is on the condition of no pretightening load. The acquired data is analyzed, and the resonance frequencies of the microstructures were derived, which verified the feasibility of testing the dynamic characteristics for micro structures with the PZT based excitation device.