Li Feng, Macdonald Niall P, Guijt Rosanne M, Breadmore Michael C
Centre for Rural and Regional Futures, Deakin University, Geelong , Private Bag 20000, 3220 Geelong, Australia.
Anal Chem. 2017 Dec 5;89(23):12805-12811. doi: 10.1021/acs.analchem.7b03228. Epub 2017 Nov 17.
Fluidic behavior in microfluidic devices is dictated by low Reynolds numbers, complicating mixing. Here, the effect of the orientation of the extruded filament on the fluidic behavior is investigated in fused deposition modeling (FDM) printed fluidic devices. Devices were printed with filament orientations at 0°, 30°, 60°, and 90° to the direction of the flow. The extent of mixing was observed when pumping yellow and blue solutions into the inlets of a Y-shaped device, and measuring the extent of mixing of two colored solutions under different angles and at flow rates of 25, 50, and 100 μL/min. Fluidic devices printed with filament extruded at 60° to the flow showed the highest mixing efficiency, but results obtained at 30° suggested more complex fluid movement, as the measured degree of mixing decreased along the fluidic channel at higher flow rates. To explore this, a device with -37° filament orientation on the top surface was designed to align with the direction of the first fluid input channel and +37° on the bottom surface of the channel to align with the direction of the second fluidic input. Results indicated a rotational movement of the fluids down the microchannel, which were confirmed by computational fluid dynamics. These results demonstrate the impact of the filament extrusion direction on fluidic behavior in microfluidic devices made by FDM printing. Two chips with laminar flow (0° filament direction) or mixing flow (+37/-37° filament direction) were used to perform isotachophoresis and colorimetric detection of iron in river water, respectively, demonstrating the simplicity with which the same device can be tuned for different applications simply by controlling the way the device is printed.
微流控设备中的流体行为由低雷诺数决定，这使得混合变得复杂。在此，研究了在熔融沉积建模（FDM）打印的流体设备中，挤出细丝的方向对流体行为的影响。设备打印时，细丝方向与流动方向的夹角分别为0°、30°、60°和90°。将黄色和蓝色溶液泵入Y形设备的入口，并在不同角度和25、50和100 μL/min的流速下测量两种有色溶液的混合程度，以此观察混合程度。细丝挤出方向与流动方向成60°的流体设备显示出最高的混合效率，但30°时的结果表明流体运动更为复杂，因为在较高流速下，沿流体通道测量的混合程度会降低。为了探究这一点，设计了一种在顶表面细丝方向为-37°以与第一流体输入通道方向对齐、在通道底表面细丝方向为+37°以与第二流体输入方向对齐的设备。结果表明流体沿微通道向下有旋转运动，这一点通过计算流体动力学得到了证实。这些结果证明了细丝挤出方向对FDM打印制造的微流控设备中流体行为的影响。分别使用两个具有层流（细丝方向为0°）或混合流（细丝方向为+37°/-37°）的芯片对河水中的铁进行等速电泳和比色检测，这表明通过简单地控制设备的打印方式，同一设备就能轻松调整以用于不同应用。
