We demonstrate an innovative method to catch the desired droplets from a train of droplets and immobilize them in traps located in an integrated microfluidic device. To this end, water-in-oil droplets are generated in a flow-focusing junction and then guided to a channel connected to chambers designated for on-demand droplet trapping. Each chamber is connected to a side channel through a batch of microposts. The side channels are also connected to the flexible poly(vinyl chloride) tubes, which can be closed by attaching binder clips. The hydrodynamic resistance of the routes in the device can be changed by opening and closing the binder clips. In this way, droplets are easily guided into individual traps based on the user’s demand. A set of numerical simulations was also conducted to investigate the authenticity of the employed idea and to find the optimal geometry for implementing our strategy. This simple method can be easily employed for on-demand droplet trapping without using on-chip valves or complex off-chip actuators proposed in previous studies.

中文翻译：

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基于流体动力阻力概念的微流控装置中按需捕获液滴的简单方法

我们展示了一种创新方法，可以从一系列液滴中捕获所需的液滴，并将它们固定在集成微流体装置中的陷阱中。为此，在流聚焦连接处产生油包水液滴，然后引导至连接到指定用于按需液滴捕获的室的通道。每个室通过一批微柱连接到侧通道。侧通道还连接到柔性聚氯乙烯管，可以通过连接活页夹将其封闭。可以通过打开和关闭长尾夹来改变装置中路径的流体动力阻力。通过这种方式，可以根据用户的需求轻松地将液滴引导到单独的陷阱中。还进行了一组数值模拟，以调查所采用想法的真实性，并找到实施我们策略的最佳几何形状。这种简单的方法可以轻松用于按需液滴捕获，而无需使用先前研究中提出的片上阀门或复杂的片外执行器。