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. Author manuscript; available in PMC: 2014 Sep 17.
Published in final edited form as: Anal Chem. 2013 Sep 4;85(18):10.1021/ac4012914. doi: 10.1021/ac4012914

Figure 2.

Figure 2

Characterization of the driving force behind fluid displacement in capillary. To fill the capillary with both oil and aqueous phase, the interfacial tension between the two fluids (γ12) has to be less than the energy required to wet the capillary (γSV − γSL), otherwise it will not be energetically favorable for both fluids to be pulled in the capillary (a). Once filling has occurred, the force to displace the fluids within the capillary is the result of an imbalance in the surface tension (b). When surface tensions are balanced, the fluids remain stationary. γ1 and γ2 are the surface tension of aqueous and oil phase, γSV and γSL are the surface tension of glass in air and glass in liquid, respectively.