温度变化引起的液晶微流动测量技术研究

发布时间：2018-08-23 10:46

【摘要】：随着微流体系统,尤其是生物芯片及芯片实验室技术的发展,微流动测量技术越来越引起人们的注意。与宏观流动相比,微流体系统中的微流动更为复杂和多样,因此宏观流动测量技术移植的方法不可行,急需根据微流动的特点研发全新的测量技术。本文针对液晶引流微驱动方式的特点,研究温度变化引起的液晶微流动测量技术。研究成果可以丰富微流体驱动领域研究方法,为液晶引流驱动的应用奠定坚实的基础。本论文所研究的主要内容如下:(1)测量系统关键仪器设计制作部分:温度变化是引起液晶微流动的关键因素,因此,测量系统必须首先能够实现对温度的精确控制。本研究运用半导体实现加热或者制冷的功能,3D打印技术进行加工制造,单片机及温度传感器作为控制系统设计制作了一种低电压经济型的显微镜电冷热台。可实现功能为:(1)可精确控制样品的升/降/恒温过程;(2)可同时施加电场。与国外同类型的产品相比价格低,适于一般实验室使用;(2)测量系统硬件搭建及测量实验部分:所搭建的测量系统硬件包括微流动流场激发、微流动观察及数据记录三大部分,并用该系统进行了温度变化引起的液晶微流动测量实验。实验过程分为两个阶段:(1)运用自制电冷热台精确控制温度的变化,实现形成大面积稳定液晶缺陷的初步目标。(2)通过温度的变化,测量液晶缺陷相互作用时发生的液晶微流动,获得了大量实验数据;(3)测量实验结果图像处理部分:这部分属于测量系统的软件部分,通过对测量实验所得的视频数据进行图像处理,以获得液晶微流动速度等数据。处理流程为通过MATLAB编程实现对测量实验视频中特定帧图像灰度数据的提取,由灰度数据计算液晶分子的倾斜角,再将得到的倾斜角带入流动方程组中求取微流动的速度等信息;(4)测量结果理论验证部分:用分子动力学计算的方法,对液晶缺陷形成及消失的温度进行了验证计算。通过Material Studio模拟软件计算平均液晶分子指向矢在不同温度下的扭转位移程度,由液晶分子平均相似度表示,进而验证液晶缺陷形成的温度范围;(5)液晶微流动控制实验部分:在成功测量了液晶微流动的基础上,运用所搭建的系统进行了微流动控制的拓展研究,利用激光雕刻机对液晶盒进行特殊处理,雕刻不同的图案,目的是定位形成不同强度的液晶缺陷,进而精确地控制液晶微流动的形成位置与过程。
[Abstract]:With the development of microfluidic system, especially biochip and microchip laboratory technology, microflow measurement technology has attracted more and more attention. Compared with macroscopic flow, microflow in micro-fluid system is more complex and diverse. Therefore, it is not feasible to transplant macro-flow measurement technology, so it is urgent to develop a new measurement technology according to the characteristics of micro-flow. In this paper, the liquid crystal microflow measurement technology caused by temperature change is studied according to the characteristics of liquid crystal drainage microdrive. The research results can enrich the research methods in the field of microfluid drive and lay a solid foundation for the application of liquid crystal drainage drive. The main contents of this thesis are as follows: (1) the design and fabrication of the key instruments of the measurement system: the temperature change is the key factor that causes the liquid crystal microflow. Therefore, the measurement system must be able to realize the accurate control of the temperature first. In this study, a kind of low voltage and economical microscope electric cooling and heating platform is designed and manufactured by using semiconductor function of heating or cooling and 3D printing technology. The single chip microcomputer and temperature sensor are used as control systems. The functions are as follows: (1) accurate control of the rise / drop / constant temperature process of the sample; (2) simultaneous application of electric field. Compared with the foreign products of the same type, it is suitable for general laboratory use. (2) the hardware of the measurement system consists of three parts: the micro-flow field excitation, the micro-flow observation and the data recording, the hardware of the measurement system is composed of three parts: the excitation of micro-flow field, the observation of micro-flow and the recording of data. The liquid crystal microflow measurement experiment caused by temperature change has been carried out with the system. The experimental process is divided into two stages: (1) the temperature change is controlled precisely by the electric cooling and heating platform, and the initial goal of forming a large area stable liquid crystal defect is realized. (2) the liquid crystal microflow occurs when the liquid crystal defect interacts with the liquid crystal defect is measured through the change of the temperature. A large number of experimental data are obtained. (3) the image processing part of the measurement results: this part belongs to the software part of the measurement system. Through the image processing of the video data obtained from the measurement experiment, the liquid crystal microflow velocity and other data can be obtained. The processing flow is that the grayscale data of a specific frame image can be extracted by MATLAB programming, and the tilt angle of liquid crystal molecules can be calculated from the gray data. Then the tilt angle is brought into the flow equations to obtain the velocity of the micro-flow. (4) the theoretical verification of the measurement results: the temperature of liquid crystal defect formation and disappearance is verified and calculated by the method of molecular dynamics calculation. The degree of torsional displacement of the average liquid crystal molecular pointing vector at different temperatures is calculated by Material Studio simulation software, and the average similarity of liquid crystal molecule is used to express the degree of torsional displacement. Then verify the temperature range of liquid crystal defect formation. (5) liquid crystal microflow control experiment part: on the basis of the successful measurement of liquid crystal microflow, the expanded research of microflow control is carried out by using the built system. The laser engraving machine is used to deal with the liquid crystal cell and carve different patterns in order to locate the liquid crystal defect with different intensity and control the position and process of the liquid crystal microflow accurately.
【学位授予单位】：河南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O753.2

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