Surface tension drawing of liquid from microplate capillary wells

Pressure differentials are routinely used to actuate flow in capillaries. We advance here an alternative means of flow generation that capitalizes on the extension of a liquid bridge achieved by the drawing of a rod through the action of surface tension. This meets the exigencies of creating controllable flow using simpler and more compact means. We found the ability to generate controllable flow to be strongly affected by the liquid bridge sustaining features, and that the use of rod diameters larger than the capillary was more conducive. The extensional flow resulting from the rupture of the liquid bridge was also found to have a strong circulation component which facilitated mixing. The approach here is highly amenable for use in capillary well microplates which have significant advantages over standard microplates. The features of this approach offer usage possibilities in biochemical applications in the field, such as in the leukocyte cell adhesion and hemagglutination tests of blood samples.

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► The pulling action on a droplet from a capillary creates controllable flow via surface tension effects.
► The flow characteristics are dependent on liquid bridge sustaining features and the rod diameter used.
► It is also possible to produce mixing together with liquid extraction when the liquid bridge ruptures.
► This approach promises important uses in biochemical analysis, particularly in the field.