Liquid droplets move readily under the influence of surface tension gradients on their substrates. Substrates decorated with parallel microgrooves, or striations, presenting the advantage of homogeneous chemical properties yet varying the topological characteristics on either side of a straight-line boundary, are considered in this study. The basic type of geometry consists of hydrophobic micro-striations/rails perpendicular to the boundary, with the systematic variation of the width to spacing ratio, thus changing the solid–liquid contact fraction and inducing a well-defined wettability contrast across the boundary. Droplets in the Cassie–Baxter state, straddling the boundary, move along the wettability contrast in order to reduce the overall surface free energy. The results show the importance of the average solid fraction and contrasting fraction in a wide range of given geometries across the boundary on droplet motion. A unified criterion for contrasting striated surfaces, which describes the displacement and the velocity of the droplets, is suggested, providing guidelines for droplet manipulation on micro-striated/railed surfaces.

中文翻译：

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对比条纹表面上的液滴运动

液滴在其基材上的表面张力梯度的影响下很容易移动。本研究考虑了装饰有平行微槽或条纹的基板，这些基板具有均匀化学性质的优势，但在直线边界的两侧改变了拓扑特征。几何的基本类型包括垂直于边界的疏水性微条纹/轨道，宽度与间距比的系统变化，从而改变固液接触分数并在边界上产生明确定义的润湿性对比。处于 Cassie-Baxter 状态的液滴跨越边界，沿着润湿性对比移动，以降低整体表面自由能。结果表明平均固体分数和对比分数在液滴运动边界上的宽范围给定几何形状中的重要性。建议使用用于对比条纹表面的统一标准，它描述了液滴的位移和速度，为微条纹/栏杆表面上的液滴操作提供了指导。