生物芯片压电微流体泵液-固耦合系统模态分析

对压电微流体泵粘性流体周期流动进行厚度积分平均近似，得到包含粘性的，非线性浅水波动方程，并采用有限元法得到微泵液体压强矩阵方程．液体压强矩阵方程和压电硅片振动有限元方程耦合，得到一个包含微泵进出口扩散管的液-固耦合系统振动方程．液-固耦合系统的模态分析结果表明，做泵液-固耦合系统的自然频率比不耦合的硅片振动自然频率低很多．随着微泵厚度的减少，液体附加质量和粘性阻尼对耦合系统自然频率的影响更加明显．同时发现，对应的压电片振型函数在液-固耦合前后没有明显变化，还给出硅片-阶模态的振幅-频率特征曲线，对薄型无阀压电微流体泵，浅水波模型合理地表达了微泵液体流动和压电硅片振动的相互作用，以及液体附加质量和粘性阻尼对微泵液-固耦合系统动力特征的影响。

MODE ANALYSIS OF LIQUID-SOLID COUPLING SYSTEM OF MICROPUMP FOR BIOCHIPS

Employs thickness integral-average method to approximate periodical flows in a piezoelectric micropump a shallow water wave equation including nonlinearity and viscous damp is presented to characterize flows in micropump. Finite element method is used to obtain a matrix equation of fluid pressure. The fluid pressure equation is combined with vibration equation of silicon diaphragm to construct liquid-solid coupling system equations for a micropump. Numerical results of mode analysis indicate that the natural frequencies of coupling system are much lowers then that of non-coupling system due to interaction of fluid pressure and silicon diaphragm vibration. The influence of added mass and viscous damp of fluid to natural frequencies of coupling system is more significant as pump thickness is smaller. It is found that the vibration shape functions of silicon diaphragm of the coupling system are almost the same as that of non-coupling system. The first order amplitude-frequency relationship of the silicon diaphragm is also given in this paper. It is necessary for an analysis of flowrate-frequency of a micropump.