Liquid flow and control without solid walls.

When miniaturizing fluidic circuitry, the solid walls of the fluid channels become increasingly important because they limit the flow rates achievable for a given pressure drop, and they are prone to fouling. Approaches for reducing the wall interactions include hydrophobic coatings, liquid-infused porous surfaces, nanoparticle surfactant jamming, changes to surface electronic structure, electrowetting, surface tension pinning and use of atomically flat channels. A better solution may be to avoid the solid walls altogether.