A note on the visualization of wetting film structures and a nonwetting immiscible fluid in a pore network micromodel using a solvatochromic dye
A note on the visualization of wetting film structures and a nonwetting immiscible fluid in a pore network micromodel using a solvatochromic dye
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DOI：
10.1029/2010wr009419
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发表时间：
2010-11
影响因子：
5.4
通讯作者：
J. Grate;Changyong Zhang;T. Wietsma;M. Warner;N. Anheier;B. Bernacki;G. Orr;M. Oostrom
中科院分区：
文献类型：
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作者：
J. Grate;Changyong Zhang;T. Wietsma;M. Warner;N. Anheier;B. Bernacki;G. Orr;M. Oostrom
微模型技术是研究孔尺度流体过程的一种有用且重要的方法，使用二维格式，可以直接可视化图案化微结构内的过程。在本技术说明中，尼罗红，9-二乙基氨基-5H-苯并[α]吩恶嗪-5-酮，被证明是一种单一的染料，其溶剂化显色性能够在含有均匀阵列的柱的孔隙网络微观模型中选择性地观察两种不混溶的液体流体。尼罗红溶解在，和分区之间，十六烷作为非润湿流体和聚乙二醇200（PEG 200）作为亲水性润湿流体在氧化硅表面的微观模型。吸收光谱和荧光发射光谱都对溶剂环境敏感，因此可以通过观察到的颜色或荧光发射带区分两相。使用明场、落射荧光、共聚焦荧光和高光谱显微镜方法对用十六烷置换模型中的PEG 200后的微模型进行成像。使用单一的溶剂化显色染料有利于直接可视化和识别的基础上的颜色在显微模型中的任何地方的两个阶段，也使每个阶段的互补荧光图像的收集。尼罗红与这些成像方法的使用有利于在特定位置处的相身份的选择性可视化;两个不混溶的液相之间的界面;孔网络内的润湿相的润湿行为;以及润湿相作为柱周围的薄膜和作为跨越孔喉的桥的保留。柱和润湿相桥形成障碍物的网络，该障碍物的网络限定用于置换非润湿相的曲折流动路径。
Micromodel technologies are a useful and important method to study pore‐scale fluidic processes, using two‐dimensional formats that enable direct visualization of processes within patterned microstructures. In this technical note, Nile red, 9‐diethylamino‐5H‐benzo[alpha]phenoxazine‐5‐one, is demonstrated as a single dye whose solvatochromism enables selective visualization of two immiscible liquid fluids in a pore network micromodel containing a homogeneous array of pillars. Nile red dissolves in, and partitions between, hexadecane as a nonwetting fluid and polyethylene glycol 200 (PEG200) as a hydrophilic wetting fluid in a micromodel with silicon oxide surfaces. Both the absorption spectra and fluorescence emission spectra are sensitive to the solvent environment, such that the two phases can be distinguished by the observed color or the fluorescence emission band. Bright field, epifluorescence, confocal fluorescence, and hyperspectral microscopy methods were used to image the micromodel after displacing PEG200 in the model with hexadecane. Using a single solvatochromic dye facilitates direct visualization and identification of both phases anywhere in the micromodel on the basis of color and also enables collection of complementary fluorescent images for each phase. The use of Nile red with these imaging methods facilitates selective visualization of phase identity at specific locations; the interfaces between the two immiscible liquid phases; wetting behavior of the wetting phase within the pore network; and retention of the wetting phase as thin films around pillars and as bridges across the pore throats. The pillars and wetting phase bridges create a network of obstacles defining a tortuous flow path for the displacing nonwetting phase.