Driving flow through a circuit with fluid walls without using an external pump

Overview
Conventional microfluidic circuits take days to make, and skill to operate. The introduction of 'Freestyle Fluidics' changes this; circuits can be made in seconds that are easy to use. These circuits have another great advantage: flow through them can be driven without using external pumps (Walsh EJ et al, 2017, Nat Commun 8, 816). In this YouTube movie (speeded up 360x), properties of fluid walls are exploited to drive flow. The drops on the left and right (initially containing 10 and 20 micro-liters of pink cell-growth medium) are connected by a conduit only a few microns high (which consequently is almost invisible). The circuit is overlaid with a transparent and immiscible liquid to prevent evaporation. Before the movie begins, differences in Laplace and hydrostatic pressure spontaneously drive flow to the right, so the left-hand drop shrinks as the right-hand one expands (above unchanging footprints). The movie (side view) begins just before 10 µl blue dye are manually pipetted into the left-hand drop. After this addition, there is still a pressure difference between the two drops, and blue dye flows to the right.

Nuclear Structure and Function Research Group