Walsh, E.J. et al. Nat. Commun. 8, 816 (2017).

Microfluidic devices have a broad range of uses in biological experiments, yet they can be complicated to build and operate. Walsh et al. develop an approach called 'Freestyle Fluidics' (FF) to overcome some of these difficulties. In FF, microfluidic devices are made with fluid, not solid, walls. Aqueous circuits with a desired pattern are printed on a surface such as a Petri dish and are then overlaid with an immiscible liquid to prevent evaporation, forming walls that can self-heal after liquids have been pipetted through them. The researchers produced a range of functional microfluidic devices using their approach, and they show that the circuits can withstand passive and active flow. They further demonstrate that their devices can be used to study an inflammatory response in human cells as well as bacterial chemotaxis.