Laplace barriers for electrowetting thresholding and virtual fluid confinement

Reported are Laplace barriers consisting of arrayed posts or ridges that impart ∼100 to 1000 s of N/m(2) Laplace pressure for fluid confinement, but the Laplace pressure is also small enough such that the barriers are porous to electrowetting control. As a result, the barriers are able to provide electrowetting flow thresholding and virtual fluid confinement in noncircular fluid geometries. A simple theoretical model for the barriers and experimental demonstrations validate functionality that may be useful for lab-on-chip, display devices, and passive matrix control, to name a few applications.