Paper-based microfluidics has been widely used in chemical and medical analysis applications. In the conventional paper-based microfluidic approach, fluid is propagating inside the porous structure, and the flow direction of the fluid propagation is usually controlled with the pre-defined hydrophobic barrier (e.g. wax). However, the fluid propagation velocity inside the paper-based microfluidic devices largely depends on the material properties of paper and fluid, the relative control method is rarely reported. In this study, a fluid propagation velocity control method is proposed for paper-based microfluidics: hydrophobic pillar arrays with different configurations were deposited in the microchannels in paper-based microfluidics for flow speed control, the result indicates the deposited hydrophobic pillar arrays can effectively slow down the fluid propagation at different levels and can be used to passively control the fluid propagation inside microchannels for paper-based microfluidics. For the demonstration of the proposed fluid control methods, a paper-based microfluidic device for nitrite test in water was also fabricated. The proposed fluid control method for paper-based microfluidics may have significant importance for applications that involve sequenced reactions and more actuate fluid manipulation.

基于纸的微流体已广泛用于化学和医学分析应用。在传统的纸基微流体方法中，流体在多孔结构内传播，流体传播的流动方向通常由预先定义的疏水屏障（例如蜡）控制。然而，纸基微流控装置内的流体传播速度很大程度上取决于纸和流体的材料特性，相关控制方法鲜有报道。在这项研究中，提出了一种用于纸基微流体的流体传播速度控制方法：在纸基微流体的微通道中沉积具有不同配置的疏水柱阵列以控制流速，结果表明，沉积的疏水柱阵列可以有效地减缓不同水平的流体传播，并可用于被动控制纸基微流体微通道内的流体传播。为了演示所提出的流体控制方法，还制造了一种用于水中亚硝酸盐测试的纸基微流体装置。所提出的用于纸基微流体的流体控制方法对于涉及序列反应和更多驱动流体操作的应用可能具有重要意义。