Exploiting fluid walls to perfuse cell cultures passively

Mammalian cells are usually cultured in vitro in polystyrene vessels (e.g. Petri dishes, microtiter plates) filled with static growth media; culture conditions poorly reflect those in vivo where cells are fed by continuous flows. In the last decades, microfluidic approaches have enabled culture in flowing environments created using external pumps, but equipment bulk and complexity have prevented wide uptake by bioscientists (e.g., it is difficult to connect external pumps to dishes in standard incubators that are often shared with others). Therefore, our aim is to feed cells growing in standard dishes continuously without using external pumps.

    Recently, an open microfluidic approach has been developed; aqueous circuits with almost any imaginable 2D shapes are fabricated in minutes on standard Petri dishes by reshaping two immiscible liquids (cell-culture medium and a bio-inert fluorocarbon, FC40). Interfaces between the two immiscible fluids act as confining fluid walls, and interfacial forces hold circuits in place. Flows through these circuits can be driven passively by local differences in Laplace pressure across the fluid walls at different points in the circuit. We are developing semi-analytical solutions that describe such flows. In contrast to the well-established theory governing flows through micro-conduits with solid walls with fixed geometries, fluid walls inevitably morph as pressures change, and this must be incorporated into the theory.