Driving flow through circuits with fluid walls without using external pumps

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 (runs 20x and 120x as indicated), properties of fluid walls are exploited to drive flow. Six identical circuits were printed on a standard 6 cm Petri dish, and overlaid with 5 ml of a transparent and immiscible liquid to prevent evaporation. The movie begins as 20 µl cell-growth medium is added to each ‘sink’ drop on the right (only the last addition is seen). Next, 10, 8, 6, 4, and 2 µl red dye are pipetted successively into left‐hand drops (bottom to top). Differences in Laplace pressure drive dye automatically from left to right. Although dye was added first to the bottom left‐hand drop, it is nevertheless dye added last that reaches a sink first.

Nuclear Structure and Function Research Group