Capillary Flow in Open Microchannels The Example of Suspended Microflows

5 Capillary Flow in Open Microchannels The Example of Suspended Microflows 

Amongst the systems based on capillarity, open systems—i.e. microflows with a free surface—are of increasing interest because of their great 

So far there have been only a few publications on suspended microfluidics [28,45,46]. Below we examine the case of a spontaneous capillary flow in suspended microchannels with parallel, vertical walls. First, we theoretically derive the conditions for SCF onset using an approach based on the Gibbs free energy [4]. Next, we verify the onset of SCF using the Surface Evolver numerical program. The dynamics of the hquid motion is then analyzed, using analytical arguments based on a force balance between the 

In this section, we first analyze the conditions for SCF in a suspended channel with vertical walls. In our analysis, gravity is neglected because the dimension of the device—here the distance between the vertical walls, denoted w—is smaller than the capillary length, i.e. 

In the case where the walls are composed of a single material (with the same functionalization), relation (1.9) yields 

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