Chien Ring-Ling, Bousse Luc
Caliper Technologies Corp., Mountain View, CA 94043, USA.
Electrophoresis. 2002 Jun;23(12):1862-9. doi: 10.1002/1522-2683(200206)23:12<1862::AID-ELPS1862>3.0.CO;2-H.
A general equation to calculate the node pressure at a junction in a microfluidic network is presented. The node pressure is generated from both the hydrodynamic flow due to the external applied hydraulic pressures and the electrokinetic flow resulted from the applied electric field. Pure electroosmotic flow has a plug-flow profile and pressure flow has a parabolic flow profile. In a first order approximation, these two flows can be treated separately, and the total flow is the sum of the two. An externally applied pressure simply creates a constant offset in the node pressure as long as the flow resistances remain the same. In a nonhomogeneous microfluidic network, where the electrical resistivity or the electroosmotic mobility is not constant everywhere, the differences in electroosmotic flow in various sections of the network will create an electroosmotically induced pressure at the internal nodes. Our theoretical approach can easily be extended to networks with more than one internal node. One prediction of this theory is that any variation in electroosmotic mobility or solution resistivity in different network branches will generate a pressure, and can thus be used as a pump. As an example, we demonstrate electroosmotic pumping in a high-low buffer system.
本文提出了一种用于计算微流体网络中节点压力的通用方程。节点压力由外部施加的液压引起的流体动力学流动以及施加电场产生的电渗流共同产生。纯电渗流具有塞流分布，压力流具有抛物线形流动分布。在一阶近似下，这两种流动可以分别处理，总流量为两者之和。只要流动阻力保持不变，外部施加的压力只会在节点压力中产生一个恒定的偏移。在非均匀微流体网络中，电阻率或电渗迁移率并非处处恒定，网络各部分电渗流的差异会在内部节点产生电渗诱导压力。我们的理论方法可以很容易地扩展到具有多个内部节点的网络。该理论的一个预测是，不同网络分支中电渗迁移率或溶液电阻率的任何变化都会产生压力，因此可以用作泵。作为一个例子，我们展示了高低缓冲系统中的电渗泵浦。
