共查询到20条相似文献,搜索用时 78 毫秒
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流体在微流通道中形成剪切流场(低雷诺数).不同于宏观体系,由于剪切力和表面张力的竞争作用,产生的液滴在微尺度下的微流通道中形成特殊的排列现象---周期性类似“晶格”排列现象.设计了新型流动聚焦型微流控芯片,分析研究在微流体系中液滴周期性图案化排列和转变机理性,液滴排列模式受两方面因素影响:水油两相的流速比值和微通道尺寸.当微通道宽度为250或300 μm时,液滴形成单层分散,双层和单层挤压排列.当微通道宽度为350 μm 时,液滴会形成单层分散到三层排列到双层挤压最后到单层挤压排列.当出口通道宽度增加到400 μm时,甚至出现了液滴四层排列的现象.同时研究了各个液滴排列模式的“转变点”. 相似文献
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研究微流控聚焦装置液滴生成特性是液滴微流控芯片结构优化设计的基础。利用水平集方法结合有限元技术建立了微流控聚焦装置内液滴生成过程的数值计算模型,并分析了分散相与连续相流速比、微流道几何结构对液滴生成机制和液滴生成特性的影响规律。在一定的流速比、微流道入口宽度比范围内,均生成了性态良好的液滴。当分散相与连续相入口宽度比大于1时,液滴尺寸随连续相入口宽度、连续相流速的增大而减小,液滴生成频率随连续相入口宽度、连续相流速的增大而增大;当分散相与连续相入口宽度比小于1时,液滴尺寸随分散相入口宽度增大而增大,随连续相流速的增大而减小,液滴生成频率随分散相入口宽度、连续相流速的增大而增大。数值计算结果表明:微流控聚焦装置液滴生成受几何结构、流速及两相流体物性参数的耦合作用,模拟计算的结果可为微流控聚焦装置结构优化设计提供指导。 相似文献
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以发射波长为473nm的二极管泵浦激光器为激发光源,搭建适于微流控液滴检测的共聚焦激光诱导荧光检测系统.系统玻璃芯片采用简易加工技术加工而成.并用2%十八烷基三氯硅烷将微通道处理为具有强疏水性质.荧光素钠溶液在T形通道交叉处被十四烷剪切形成液滴,液滴流经检测点时被激光诱导荧光系统检测.荧光素钠的检出限为1.1×10<'... 相似文献
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液滴不对称分裂是获得不同尺寸微液滴的优选方法,研究液滴不对称分裂行为对于生物医学、能源化工及食品工程等领域具有重要意义.本文研制T型微通道芯片并设计搭建T型微通道液滴半阻塞不对称分裂行为可视化实验平台,研究流量调控对微液滴分裂比的影响规律,并建立理论模型对分裂比进行预测,得到以下结论:液滴不对称挤压分裂过程分为挤压前期、挤压后期和快速夹断阶段,在挤压前期,液滴颈部宽度随时间呈线性变化,在挤压后期,颈部宽度随时间呈指数关系,而在快速夹断阶段,液滴颈部向心收缩的界面附加压力占主导,液滴颈部宽度剧烈收缩,呈断崖式减小;调控分支通道流量可对液滴不对称分裂比进行调控,且调控作用受毛细数影响较大;基于液液流动压降模型的液滴分裂比预测模型能够有效预测液滴分裂比. 相似文献
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Demonstration of Four Fundamental Operations of Liquid Droplets for Digital Microfluidic Systems Based on an Electrowetting-on-Dielectric Actuator
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An electrowetting-on-dielectric actuator is developed, in which the liquid is sandwiched between top and bottom plates. For the bottom plate, silicon wafer is used as the substrate, the heavily phosphorus-doped polysilicon film is deposited by low pressure chemical vapour deposition as the microelectrode array, and thermally grown SiO2 film as the dielectric layer. The top p/ate is a glass plate covered with transparent and conductive indium tin oxide as the ground electrode. In addition, a Teflon AF1600 film is spun on the surface of both the plates as the hydrophobic layer. The experimental results show that when the gap height between two plates is 133μm, a prototype of the device is capable of creating, transporting, merging and dividing droplets of deionized water in an air environment with a 70V at lOHz voltage pulse. This is also established by simulations using the computational fluidic software of CFD-ACE+. 相似文献
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复方甲硝唑片含量测定方法的比较 总被引:1,自引:0,他引:1
文章经选择适当的测定波长,同时采用系数倍率法和联立方程组新解法不经提取分离直接测定复方甲硝唑片中甲硝唑和维生素B_6的含量。同时采用河北省药品标准法进行了对比测定。利用SPSS统计软件通过对各方法的测定结果做方差分析,结果表明:新建立的系数倍率法和联立方程组新解法的测定结果无显著性差异,而两法分别与河北省药品标准法的测定结果比较,均存在显著性差异。作者认为:河北省药品标准法经过烦琐的提取分离过程,引入的误差较大。而新建立的两法简便、快速、准确,优于河北省药品标准法。 相似文献
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T. Gilet D. Terwagne N. Vandewalle 《The European physical journal. E, Soft matter》2010,31(3):253-262
We present the results of a combined experimental and theoretical investigation of oil droplets sliding on fibres. First,
both the axisymmetric shape and the motion of a droplet on a vertical fibre are described. The motion is shown to result from
a balance between the droplet weight and the viscous stresses. On a long-term range, the droplet loses some mass through coating
the fibre, which decreases its velocity. In a second time, we rationalize the behaviour of a droplet that encounters a junction
between vertical and horizontal fibres. Depending on its size, the droplet may cross the junction or remain blocked. The transition
is well described by an ordinary differential equation equivalent to a damped harmonic oscillator truncated to the neighbourhood
of the horizontal fibre. This simple system is the basic element for more complex fiber networks that would be useful in microfluidic
applications involving droplets. 相似文献
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LED准直器设计中复合抛物面同步多曲面方法 总被引:4,自引:0,他引:4
利用非成像光学中流线法和同步多曲面(SMS)法,设计一种具有发散角小、均匀度好和光效高的LED准直器。设计中由复合抛物面(CPC)完成初级配光,将朗伯光源±90°的发散角缩小到±45°,再以SMS法设计的多重自由反射曲面实现准直均匀配光,并由光学扩展量给出准直器的理论光效,最后引入平顶宽度、平顶光效和平顶均匀度等的定义,以更好地反映准直光束质量。光学仿真结果表明,准直器的发散角小于±2.26°,整体光效达到0.79,理论与仿真光效的误差小于2.5%,在0.9平顶宽度范围内光斑均匀度大于等于0.9,平顶光效为0.56,效果良好。 相似文献
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Hyväluoma J Koponen A Raiskinmäki P Timonen J 《The European physical journal. E, Soft matter》2007,23(3):289-293
The behaviour of liquid droplets on inclined heterogeneous surfaces was simulated by the lattice-Boltzmann method using the
Shan-Chen multiphase model. The effect of topography of the surface on the contact angle hysteresis was investigated. It is
shown in particular, by using anisotropic rough surfaces, how surface topography and thereby the continuity of the three-phase
contact line, affect this hysteresis. Our results clearly indicate that the superhydrophobicity of a surface cannot be judged
by the contact angle alone. 相似文献
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微流控芯片系统中测温及控温装置的研制 总被引:2,自引:0,他引:2
报道了一种结构简单、成本低、操作方便、应用于微流控芯片系统中温度测量及温度控制的装置。该系统以CCD摄像机、荧光显微镜及图像采集卡构成的非接触荧光指示剂测温装置,实现了微流体空间温度分布测量以及随时间变化的温度测量。提出了以透明氧化铟锡薄膜玻璃作为加热元件,采用PID控制算法的温度控制平台,稳态时温度控制精度可达到±0.1 ℃。采用该测温和控温装置研究了玻璃微流控芯片微通道内溶液温度在空间上和随时间的变化情况,结果表明该方法简单、有效,可达到μm级的空间分辨率和ms级的时间分辨率。 相似文献
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Up to now, measured results of the contact angle on rough surfaces have been explained usually based on the Wenzel equation (1936) and the Cassie-Baxter equation (1944). However, these equations do not take into account considerations of liquid wetting behaviors on rough surfaces, and this leads to poor understanding of the mechanisms of contact between liquid droplets and rough surfaces (e.g. contact angle hysteresis). We propose a new model for the contact angle of liquid droplets. By means of the present model, we can well understand the evperimental data which could not be well explained by the Wenzel equation and the Cassie-Baxter equation. 相似文献
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By using a semi-empirical Lennard-Jones embedded-atom-method potential, we study the influence of many-body forces and atomic size mismatch on the wetting behavior of nano droplets on a solid surface. With molecular dynamics simulations, we find that the contact angle decreases with increasing many-body forces. The increase of atomic size mismatch between solid and liquid results in the decrease of contact angles. Our calculation also shows that the interface structure is strongly affected by the interaction between liquid and solid as well as the atomic size mismatch. For weak solid-liquid interaction, the interface layer of the droplet nearest to the solid exhibits a typical simple liquid structure regardless of the size mismatch. For strong solid-liquid interaction, evident ordering in the interface layer is observed for well matched cases. 相似文献