【作者】 张敬涛；

【导师】 魏守水；

【作者基本信息】 山东大学 ， 生物医学工程， 2010， 硕士

【摘要】 随着MEMS技术在生物医学分子检测和生化分析领域的广泛应用,微型构件中流体的驱动与控制技术的研究已逐渐成为一个热点。超声行波驱动在原理上不同于当前各种微流体驱动技术,它是利用压电陶瓷的逆压电效应产生超声振动在输送管道壁上激起行波,使管道内的液体产生行波声场,在雷诺切应力、声流、声辐射压力、管壁黏附力和液体分子间的作用力共同作用下,使液体沿行波方向运动,是一种新的微流体驱动技术。作为一种新型微流体驱动技术,超声行波驱动没有可动部件,所需驱动电压低,材料选择较广泛,可适用于各种环境,具有广泛的应用前景。本文针对国家自然科学基金(项目编号：10572078)和山东省自然科学基金(项目编号：Y2007A16)项目中有关超声行波微流体驱动与控制技术的基本理论和驱动模型,从声学和动力学分析的角度进行了较为深入的研究。首先,概述了微机电系统(MEMS)及微流体系统的发展现状,对目前的几种微流体驱动与控制技术作了介绍。基于压电陶瓷的逆压电效应及其材料特性和频率特性,简述了行波的合成,通过对声辐射压力及声流产生机理的研究,得出驱动机理与模型参数的关系,为超声行波微流体的驱动控制打下理论基础。然后,利用ANSYS有限元软件,对圆环形模型结构、动力学特性进行了分析研究。通过有限元模态分析,讨论了模型固有频率与基体结构参数的关系。通过基于逆压电效应的激振响应分析,激励出所需振型,得出了响应位移随频率的变化特性,为模型的进一步优化设计提供指导。通过瞬态动力学分析,得出模型起振过程的响应情况。为以后的课题研究打下了坚实的基础。最后,针对接下来的难点耦合场分析,通过ANSYS中的FSI(流固耦合接口),建立模型实现了声学流体单元和固体单元(弹性体和压电体)的耦合,并得到了圆环沟道内声压的分布图,从而对研究声流和声压在流体驱动中的作用又前进了一步。对圆环流固耦合模型进行瞬态动力学分析,得到沟道内流体在超声行波激励下的流场情况,比较不同时间子步时流体域和固体域的位移云图,得到流体随固体振动情况,分析不同时间子步时流体域的速度矢量图,得到流体在超声行波方向上的流动情况,也是对我所做的整个工作的总结。更多还原

【Abstract】 With the development of MEMS technique, fluid driving and controlling technique in the micron components has become one research issue. The driving and controlling of microfluid is largely different from that of macrofluid. It is mostly because when the dimension decreases to micron level, the flow characteristic of fluid has changed a lot as a result of the influence of scale and surface effect. The change usually makes the transplantation of macrofluid driving and controlling technique to microfluid field unsuccessful or unfavorable, because microfluid driving and controlling technique is more complex and diversified. Ultrasonic traveling wave driving is different from the present microfluid driving techniques in principle. Using the anti-piezoelectric effect of piezoelectric ceramic, ultrasonic vibration is generated and the traveling wave is generated on the bottom surface of microchannel, and acoustic field is generated simultaneously. The liquid in the microchannel move along the direction of traveling wave because of the collective effect of shearing Reynolds stress, acoustic streaming, acoustic radiation pressure, viscous force and molecular force. As a new microfluid driving technique, ultrasonic traveling wave driving technique has no movable components, needs lower driving voltage, can adapt to all kinds of environment, so it will has extensive application in the future.This dissertation is supported by Nation Nature Science Foundation of china (No.10572078), Shandong Province Nature Science Foundation (No.Y2007A16). For the feasibility and driving model of ultrasonic traveling wave microfluid driving and controlling technique of the items, this paper has an embedded research from the view of acoustic and dynamics analysis.Firstly, the status of microflow driving technique inside and outside the country is introduced, the mechanism of traveling wave’s generating are particularly analyzed, and the anti-piezoelectric effect, the character of material and frequency of piezoelectric ceramics, which makes a base for the driving and control of traveling wave microfluid, are also presented. The relation between driving mechanism and model parameters is given from the research on the forming mechanism of acoustic radiation pressure and acoustic streaming.Secondly, based on the analysis of the Finite Element Method (FEM), it discusses the relation between model’s natural frequency and elastic body parameters. By the harmonic response analysis based on the anti-piezoelectric effect, the anticipated vibration mode is successfully excited at the point of resonance frequency, and the frequency characteristic of response amplitude is obtained. To the coupling field analysis, the following difficult issue, by the FSI in ANSYS, a model is built to accomplish the coupling between acoustic-fluid units with solid ones. The acoustic pressure distribution of circular panel channel is obtained, which make a great contribution to the study of acoustic streaming and pressure function in microfluidic driving.Finally, transient dynamic was made to the circle model, and the streamline in the fluid domain and velocity vector of the interface is obtained, which prove the feasibility of microfluidic driving and summarize my whole work.更多还原