Estimation of Size and Contact Angle of Evaporating Sessile Liquid Drops Using Texture Analysis

Size
and contact angle of liquid drops are fundamental parameters
in interfacial science. Accurate estimation of these parameters can
provide objective information regarding several properties of the
contacting surface. We leveraged principles of texture analysis to
estimate the contact angle and the drop diameter from videos of evaporating
sessile liquid drops deposited on solid surfaces. Specifically, we
used a Harris corner detector to locate the corners and dynamically
estimate the changing size and a Gabor wavelet-based approach to estimate
the varying contact angle of the evaporating sessile drop. We demonstrated
the ability of our approach to accurately estimate size and contact
angles of drops deposited on a hydrophilic glass slide and on a paraffin
film representing a hydrophobic surface. We also estimated the contact
angle and size of drops deposited on horizontal and tilted surfaces
to generate symmetric and asymmetric drop shapes, respectively. A
software application that has the ability to analyze videos of sessile
liquid drops as inputs is provided, and this tool can generate plots
of the estimated contact angle and the drop diameter as a function
of frame number.

液滴尺寸与接触角是界面科学中的基础核心参数。精准估算这两类参数，可获取固液接触表面的多项客观属性信息。本研究借助纹理分析原理，针对沉积于固体表面的蒸发静驻液滴（sessile liquid drop）的视频，实现接触角与液滴直径的估算。具体而言，本研究采用哈里斯角点检测器（Harris corner detector）定位角点并动态估算液滴尺寸变化，同时借助基于Gabor小波（Gabor wavelet）的方法，对蒸发静驻液滴的接触角动态变化进行估算。本研究验证了所提方法的准确性：分别在亲水玻璃载片与代表疏水表面的石蜡薄膜上沉积液滴，均可精准估算其尺寸与接触角。此外，本研究还在水平与倾斜表面上沉积液滴以分别生成对称与非对称液滴形态，并估算了对应液滴的接触角与尺寸。本研究提供了一款可输入静驻液滴视频进行分析的软件应用，该工具可生成估算接触角与液滴直径随帧数变化的关系曲线。