十字型微谐振梁多场耦合振动及信号分析

Multi-field Coupling Vibration and Signal Analysis of Cross Microresonator

微机电系统(MEMS)又称微系统或微电子机械系统,是在微电子技术基础上发展起来的一种高科技微型器件或系统。MEMS集光刻、腐蚀、LIGA、硅和非硅表面微加工、精密机械加工等技术于一体,其尺寸在微米量级。利用微加工技术生产的微传感器以结构简单、灵敏度高和工作稳定等特点而广泛应用于工程实际中。微传感器通常采用静电激励与电容检测方法检测信号,即利用谐振梁振动时的位移变化导致电极之间的距离变化,从而使电极之间的电容值产生变化,检测到的电容变化频率即为谐振梁振动的频率。为解决微传感器电容检测信号微弱、检测精度较低的问题,提出了一种十字型微谐振梁。为研究微谐振梁的多场耦合效应,在考虑范德华力、电场力的情况下建立了谐振子的多场耦合非线性动力学方程。采用林滋泰德-庞加莱法求解获得其非线性振动的动态位移,分析了多物理场参数对于谐振子振动位移平均值以及电容变化量的影响规律。运用微纳加工手段制作出十字型微谐振梁,采用静电激励-电容检测方法进行了谐振频率和振动位移导致的电容变化量测试。结果表明:十字型谐振梁增大了极板面积,电容变化量增加,其信号强度更强。当面积增大75%时,电容变化量为原来的4.2倍,信号强度增强5.0倍,因此更加便于电容检测。

Micro-Electro-Mechanical System(MEMS), also known as microsystem or micro-electro-mechanical system, is a high-tech micro device or system developed on the basis of microelectronic technology. MEMS integrates photolithography, corrosion, LIGA, silicon and non-silicon surface micromachining, precision machining and other technologies, and its size is on the micron scale. The microsensors produced by micromachining technology are widely used in engineering practice because of their simple structure, high sensitivity and stable operation. The microsensor usually uses electrostatic excitation and capacitance detection to detect the signal, that is, the displacement change of the resonator during vibration leads to the change of the distance between two electrodes, so as to change the capacitance between electrodes, thus the detected capacitance change frequency is the frequency of resonantor vibration. A cross microresonator was proposed to solve the problem of weak capacitance signal and low detection accuracy of microsensor. To study the multi-field coupling effect of microresonator, the multi-field coupling nonlinear dynamics equation of harmonic oscillator was established considering Van der Waals force and electric field force. The dynamic displacement of nonlinear vibration was obtained by using Linz Ted-Poincare method, and the influence of multiple physical field parameters on mean vibration displacement and capacitance variation of the harmonic oscillator was analyzed. The cross microresonator was fabricated by micro-nano machining, and the capacitance variation resulted from resonant frequency and vibration displacement was measured by electrostatic excitation-capacitance detection method. The results show that the cross microsensor increases the plate area,thereby aggrandizing the capacitance variation, and thus the signal intensity becomes stronger. When the plate area increases by 75%, the capacitance change is 4. 2 times of the original, and the signal intensity increases by 5. 0 times, so it is more convenient for capacitance detection.