Novel characterization of microdrops and microbubbles in emulsions and foams using atomic force microscopy.
Novel characterization of microdrops and microbubbles in emulsions and foams using atomic force microscopy.
复制标题
使用原子力显微镜对乳液和泡沫中的微滴和微泡进行新的表征。
作者：
Md Hemayet Uddin;Sin;R. Dagastine
液滴或气泡的界面的性质以及它们之间的动态相互作用通常介导或控制在溶剂萃取、泡沫浮选、食品、个人护理产品和微流体以及许多生物过程中的乳液和泡沫的配制和加工中的宏观行为。这些界面的表征通常是复杂的，因为液滴和气泡的尺寸小，范围可以从微米级到数百微米。我们报告的直接测量的表面或界面张力的水溶液中的液滴或气泡的浓度和类型的表面活性剂的函数，使用原子力显微镜（AFM）和最近开发的纳米针AFM悬臂。我们还证明了这种大小的成像液滴或气泡的可行性，通过系统的研究参数，包括悬臂弹簧常数，尖端几何形状，成像力，反馈设置以及AFM制造商在两个轻敲和接触成像模式。成像研究表明，使用AFM可视化复杂的结构在油-水或空气-水界面的可行性，以及如何同心环文物在文献中观察到的早期AFM仪器的局限性的结果。
The nature of the interface of drops or bubbles and the dynamic interactions between them often mediate or control macroscopic behavior in the formulation and processing of emulsions and foams in solvent extraction, froth flotation, food, personal care products, and microfluidics as well as in many biological processes. Characterization of these interfaces is often complicated due to the small size of the drops and bubbles that may range from the micrometer scale to hundreds of micrometers. We report the direct measurement of the surface or interfacial tension of drops or bubbles in aqueous solutions as a function of the concentration and type of surfactant, using atomic force microscopy (AFM) and a recently developed nanoneedle AFM cantilever. We also demonstrate the viability of imaging drops or bubbles of this size in both tapping and contact imaging modes through a systematic study of parameters, including cantilever spring constant, tip geometry, imaging force, and feedback settings as well as the AFM manufacturer. The imaging study demonstrates the viability of using AFM to visualize complex structures at the oil-water or air-water interface as well as how concentric ring artifacts observed in the literature are the result of earlier AFM instrument limitations.