微膜生化传感器在液态介质中的动态力学性能研究

The dynamic characteristics of micro biochemical sensors are well known to strongly depend on the size effect and residual stress of micro components, liquid media, attached mass and so on. In this project, we plan to study on dynamics of the microdiaphragm biochemical sensors, considering the size effect of mechanical behavior in microdiaphragm and the coupled action from liquid media. In theory, the dynamic theoris based on the strain grdient elasticity are fisrt developed for microdiaphragm by incorporating strain-dependent residual stress terms into the equations of motion, which are able to describe the influence from the size effect of mechanical behavors in microdiaphragm and residual stress. Then, the liquid-solid coupling dynamics models are developed for microdiaphragm in contact with visious liquid. The effects of microdiaphragm characteristic dimensions, residual stress, medium viscosity and attached mass will be analyzed in detail. The energy dissipation mechanism and damping characteristics during the vibrating process of micro diaphragm in liquid will be explored theoretically. In the numerical simulation, the smoothed finite element method is first proposed for the microdiaphragm dynamic theory including the effects of size effect and residual stress. Then, the smoothed finite element-based dynamic simulation models are developed for both single nicrodiaphragm biochemical sensors and array microdiaphragm biochemical sensors in liquid media. The dynamic characteristics and detected performance of microdiaphragm biochemical sensors during detecting biochemical visious medium will be simulated by use of numerical methods. The research results in this project will provide the basic theories for the optimization design, detection and control of microdiaphragm biochemical sensors.

微构件尺寸效应、残余应力、介质、吸附物等都对微膜传感器的动力学性能有着重要的影响。在本项目中，针对谐振式微膜传感器中的动力学问题，考虑微膜的尺寸效应和液态生化介质的耦合作用，开展微膜传感器动态力学性能研究。在理论上，建立可描述微膜尺寸效应和残余应力影响的微膜动力学理论模型，揭示特征尺寸、残余应力对微膜动力学特性的影响规律，进而研究液体中微膜动力学特性，探讨微膜在液态介质中振动过程的能量耗散机理及阻尼特性；在数值方法上，建立描述尺寸效应和残余应力影响的微膜理论数值分析方法，并发展单膜片和阵列膜片微膜生化传感器的动力学特能数值模拟技术，模拟分析微膜生化传感器的动态检测性能。研究成果可为微膜生化传感器的优化设计、检测和控制提供依据

微膜作为谐振器传感器的换能器件，其动力学性能对传感器的检测性能起着决定性作用。然而，微环境条件下，微膜的动力学性能存在着明显的尺寸效应。在本项目中，对刻画微构件尺寸效应的基本理论及表面效应、介质、吸附物等因素对微膜静动态力学性能的影响进行了系统研究。项目研究工作取得主要成果包括：通过将应变梯度张量及其功共轭的高阶应力张量分解成两组4个正交分量，从理论上证明了各向同性材料独立的尺度参量个数仅有3个，解决了应变梯度理本构关系的基本理论问题，提出了一种尺度参量独立的各向同性应变梯度弹性理论；将独立分量形式的应变梯度理论拓展于各向同性电介质的挠曲电问题，分析了挠曲电效应中的力电耦合关系，建立了一种高阶分量独立形式的挠曲电弹性理论，为研究挠曲电效应产生机制奠定了理论基础；应用应变梯度理论，建立了描述微膜静动态性能尺寸效应的理论模型，分析了微膜静动态性能对特征尺寸的依赖性；建立了反映表面效应、残余应力及吸附物影响的微膜动力学模型，探明了上下表面不同效应、残余应力及吸附物对微膜自振特性、敏感性的影响规律，并与势流体模型耦合，建立了液体中微膜的流固耦合动力学模型，分析了微膜液体中振动的声辐射能量耗散特性，探讨了液体对微膜品质因素的影响及品质因素的尺寸依赖性；对于中性轴（面）不可预知的弯曲变形，提出了一种含未知偏移量的位移模式，用位移变分法，建立了常规材料层合和含压电层合的微梁、微膜动力学模型，系统探讨了层合微梁和微膜的自振特性及其尺寸依赖性，考虑声辐射耗散和压电迟滞耗散，给出了微膜品质因素的预测模型，得到了与实验测试结果相吻合预测结果。应变梯度理论和挠曲电理论的成果为深入研究微结构尺寸效应和电介质构件力电耦合问题奠定了理论基础，微膜动力学性能的研究成果可为微膜传感器设计、检测与控制提供了理论依据。