Development of flow-less linear gradient microfluidic devices*

Our previous work showed that by splitting and recombining the input flows through a combination of bifurcated and trifurcated channels one can generate a linear chemical gradient across a microfluidics chamber. However, when such devices are meant to study cell migration one must consider that physical factors of the microenvironment have influences in regulating cell fate. Such biomechanical cues have gained significant attention in recent years for their roles in defining fundamental cell properties, including motility, chemotaxis and migration. One such factor is the mechanical stress introduced by the flow in the gradient chamber that induces shear stress thus impacting the migration patterns. In this work we present a microfluidics device that generates highly linear chemical gradients into a cell culture chamber that is separated, flow-wise, from the gradient chamber and any investigated live cells will not experience any confounding fluid flows. The slope and the offset of the gradient can be manipulated with respect to experimental needs to enhance migration.