The State Key Lab of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Lab Chip. 2014 Apr 7;14(7):1357-66. doi: 10.1039/c3lc51222c.
In this study, we developed a new method for the direct measurement of differential pressures in a co-flow junction microfluidic device using a Capillary Laplace Gauge (CLG). The CLG - used inside the microchannel device--was designed using a tapered glass-capillary set up in co-flow junction architecture with a three-phase liquid-liquid-gas system with two flowing liquid phases and an entrained gas phase. By taking advantage of the Laplace equation, basic geometric relations and an integrated image analysis program, the movement of the entrained gas phase with the flow of the liquid-phases is tracked and monitored, allowing the gauge to function as an ultra-sensitive, integrated, differential pressure sensor measuring fluctuations in the liquid-dispersed phase channel pressure as small as tens of Pascals caused by droplet formation. The gauge was used to monitor the drop formation and breakup process in a co-flow junction microfluidic device under different flow conditions across a large range (1 × 10(-3) to 2.0 × 10(-1)) of capillary numbers. In addition to being able to monitor short and long term dispersed phase pressure fluctuation trends for both single drop and large droplet populations, the gauge was also used to clearly identify a transition between the dripping and jetting flow regimes. Overall, the combination of a unique, integrated image analysis program with this new type of sensor serves as a powerful tool with great potential for a variety of different research and industrial applications requiring sensitive microchannel pressure measurements.
在这项研究中，我们开发了一种新的方法，用于使用毛细拉普拉斯计 (CLG) 直接测量对流传质微流控装置中的差压。CLG - 用于微通道装置内 - 采用在对流传质结构中设置的锥形玻璃毛细管设计，具有三相液 - 液 - 气系统，其中有两个流动的液相和夹带的气相。利用拉普拉斯方程、基本几何关系和集成的图像分析程序，跟踪和监测夹带气相随液相流动的情况，使该仪表能够作为超灵敏、集成的差压传感器，测量由液滴形成引起的小至数十帕斯卡的液体分散相通道压力波动。该仪表用于监测在不同流动条件下（在很大范围内（1×10(-3)至 2.0×10(-1)))的对流传质微流控装置中的滴形成和破裂过程。除了能够监测单滴和大液滴群体的短期和长期分散相压力波动趋势外，该仪表还用于清楚地识别滴流和射流流动状态之间的过渡。总的来说，这种独特的、集成的图像分析程序与这种新型传感器的结合，为需要敏感微通道压力测量的各种不同的研究和工业应用提供了一种强大的工具，具有巨大的潜力。
