Measuring the Nonuniform Evaporation Dynamics of Sprayed Sessile Microdroplets with Quantitative Phase Imaging
Measuring the Nonuniform Evaporation Dynamics of Sprayed Sessile Microdroplets with Quantitative Phase Imaging
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DOI：
10.1021/acs.langmuir.5b02148
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发表时间：
2015-10-13
期刊：
影响因子：
3.9
通讯作者：
Goddard, Lynford L.
中科院分区：
文献类型：
--
作者：
Edwards, Chris;Arbabi, Arnir;Goddard, Lynford L.
我们展示了实时定量相位成像作为一种新的光学方法来测量固着微滴的蒸发动力学。在蒸发过程中捕获各种液滴的定量相位图像。这些图像使我们能够生成具有纳米精度的液滴形状的时间分辨三维地形轮廓，并且无需对液滴几何形状进行任何假设，直接测量表征表面润湿过程的重要物理参数。具体而言，随时间变化的液滴的高度，体积，接触半径，接触角分布沿着液滴的周长，和质量通量密度为两个不同的表面制备报告。这些研究清楚地表明了先前报道的蒸发的三个阶段：钉扎、脱钉和干燥模式;这些研究还揭示了部分钉扎的实例。最后，利用该装置对喷雾液滴的协同蒸发进行了研究。我们观察和解释的邻居引起的蒸发率降低，也就是说，相比孤立的液滴的预测。在未来，新的实验方法应该刺激气液固界面上的胶体粒子动力学的探索。
We demonstrate real-time quantitative phase imaging as a new optical approach for measuring the evaporation dynamics of sessile microdroplets. Quantitative phase images of various droplets were captured during evaporation. The images enabled us to generate time-resolved three-dimensional topographic profiles of droplet shape with nanometer accuracy and, without any assumptions about droplet geometry, to directly measure important physical parameters that characterize surface wetting processes. Specifically, the time-dependent variation of the droplet height, volume, contact radius, contact angle distribution along the droplet's perimeter, and mass flux density for two different surface preparations are reported. The studies clearly demonstrate three phases of evaporation reported previously: pinned, depinned, and drying modes; the studies also reveal instances of partial pinning. Finally, the apparatus is employed to investigate the cooperative evaporation of the sprayed droplets. We observe and explain the neighbor-induced reduction in evaporation rate, that is, as compared to predictions for isolated droplets. In the future, the new experimental methods should stimulate the exploration of colloidal particle dynamics on the gas liquid solid interface.