基于压电效应和液晶引流效应微流体组合驱动控制机理研究

For the shortcoming of small driving force in the existing micro-fluidics drive and control technology. A new micro-fluid driving model based on the piezoelectric effect and liquid crystal backflow effect has been brought forward. The primary tasks of the project are piezoelectric effect and liquid crystal backflow effect mechanism research, the coupling effect research between mechanic, electric and liquid crystal field. According to piezoelectric coupling theory the stress and strain equation of circular, dissymmetrical, monolayer piezoelectric drivers with the neuter face will be established. The control equation of the piezoelectric drivers will be set up according to energy variation principle with piezoelectric coupling theory. According to liquid crystal L-E theory the electric vector, liquid crystal volume tensor, force vector will be established and the liquid crystal backflow effect angular motion and motion equation will be built with the double electric fields, the fluid-solid section force. Finally the dynamics equations of multi-field coupling with the combined driven. Through Micro-PIV experimentation the complicated multi-factorial prediction model will be founded in view of the driving parameters, geometry parameters and physics parameters, and so on. The purpose of this project will lay a theoretical and technical foundation to solve the performance forecast difficult of hybrid driven and development of novel micro actuator actuating properties. In addition to this driving manners will have good application prospect in biological, iatrical, aeronautical and space aspects.

针对现有微流体系统中存在的驱动力小的缺点，提出基于压电效应和液晶引流效应微流体组合驱动与控制技术。研究微尺度组合驱动模式下压电效应、液晶引流效应驱动机理，重点探讨电场、应力场和液晶场间的耦合作用。以压电耦合理论为基础，推导单层圆形非对称压电驱动器相对于中性面应力、应变表达式，基于能量变分原理，建立微尺度下压电驱动器控制方程；以液晶Leslie-Ericksen理论为基础，考虑液晶引流和压电效应双电场、流固耦合界面作用力的影响，确定电场矢量、液晶体积张量、外力矢量，建立液晶角运动、运动方程；最终确定组合驱动多场耦合数值分析动力学方程组。制定组合驱动Micro-PIV实验方案，分析驱动参量、几何参量、物性参量等外界因素对驱动性能的影响，建立基于复杂多因素组合驱动性能定量预测模型，为有效解决微流体驱动性能预测难题和研制出新型微驱动器提供理论和技术支撑，拓宽其在生物医疗、航空航天等方面的应用前景。

对压电效应和液晶引流效应组成的新型组合驱动模式控制机理进行分析，以宏观压电耦合理论为基础，推导出了压电驱动器相对于中性面应力、应变表达式以及正弦交流信号驱动下的压电驱动器控制方程；采用传统L-E理论，考虑组合驱动模式下压电效应电场和外加电场的影响，对液晶分子角运动方程中的电场矢量进行修正，推导出组合驱动模式下的新的液晶分子角运动方程；考虑双电场下液晶分子外力矢量，流固耦合作用下的外力以及微流道不对称布置引起的压力差，对运动方程种的压强P进行了修正，从而确定了组合驱动模式下的运动方程；最终建立了组合驱动模式下的多场耦合的数值分析方程组。对组合驱动模式下二维和三维结构进行多场耦合流场数值分析，初步结果显示组合驱动模式下系统性能优于单一驱动模式。采用玻璃湿法腐蚀工艺加工制作出微流道，高温键合法对微流道进行封装，最后采用PDMS紫外光照射不可逆粘贴法对微泵整体结构进行封装；搭建Micro PIV流场测试平台，分别对单一驱动模式下和组合驱动模式下微泵流量和流场进行测试，结果与数值分析结果相吻合。