Abstract Since their introduction, paper-based microfluidic analytical devices (μPADs) have been ubiquitously utilized for different applications. The spontaneous imbibition of liquids in the paper-based devices that eliminates the requirement of an external pumping system has played a primary role in making paper an appropriate alternative for many other materials in the fabrication of microfluidic devices. Wax patterning is one of the most common methods to fabricate μPADs. Dynamics of the flow in channels with wax boundaries deviate from Washburn's law. Despite some research performed to model the effects of wax boundaries, some gaps remain in the presented models. A more general model is needed to account for the effects of wax boundaries and evaporation simultaneously. In this work, we present a general model to model the wax boundaries by introducing a coefficient in the equation of wicking height. We verify our model experimentally for relative humidities of 100% and 20%. Results show that our model can predict wax boundaries effect on imbibition height with considerable accuracy.

中文翻译：

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蜡边界与蒸发相结合对纸基装置中流体流动动力学的影响

摘要 自推出以来，纸基微流体分析装置 (μPAD) 已被广泛用于不同的应用。液体在纸基设备中的自发吸收消除了对外部泵系统的要求，这在使纸成为微流体设备制造中许多其他材料的合适替代品方面发挥了主要作用。蜡图案是制造 μPAD 的最常用方法之一。具有蜡边界的通道中的流动动力学偏离了沃什伯恩定律。尽管进行了一些研究来模拟蜡边界的影响，但所呈现的模型中仍然存在一些差距。需要一个更通用的模型来同时考虑蜡边界和蒸发的影响。在这项工作中，我们通过在芯吸高度方程中引入一个系数来提出一个通用模型来模拟蜡边界。我们针对 100% 和 20% 的相对湿度通过实验验证了我们的模型。结果表明，我们的模型可以相当准确地预测蜡边界对渗吸高度的影响。