Transport of droplets on surfaces is important for a variety of applications such as micro liquid handling and biochemical assays. Here, we report evaporation-induced attraction, chasing, and repulsion between a target pure aqueous (water) droplet and a driver aqueous mixture droplet comprising water and a lower surface tension and lower vapor pressure liquid on a high energy surface. It is observed that for a fixed concentration of the mixture droplet, attraction/chasing or repulsion can be achieved by varying the relative time instants at which the drops are dispensed. Our study reveals that if the water droplet is dispensed within a critical time after dispensing the mixture droplet, the latter will get attracted to and chase the water droplet. On the other hand, if the water droplet is dispensed after this critical time, then it would get repelled from the mixture droplet. We explain the underlying mechanisms that govern the phenomena and demonstrate continuous transport of liquid/cell sample droplets/plugs.

中文翻译：

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含水混合物液滴对纯水液滴的蒸发诱导传输

液滴在表面上的传输对于各种应用（例如微量液体处理和生化分析）非常重要。在这里，我们报告了目标纯水性（水）液滴与包含水和低表面张力和低蒸气压液体的驱动水性混合物液滴之间的蒸发诱导的吸引力、追逐和排斥。据观察，对于固定浓度的混合物液滴，可以通过改变分配液滴的相对时间瞬间来实现吸引/追逐或排斥。我们的研究表明，如果在分配混合液滴后的关键时间内分配水滴，后者将被吸引并追逐水滴。另一方面，如果水滴在这个临界时间之后分配，然后它会被混合物液滴排斥。我们解释了控制现象的潜在机制，并展示了液体/细胞样品液滴/塞子的连续传输。