Pipette-friendly laminar flow patterning for cell-based assays.

Laminar flow patterning (LFP) is a characteristic method of microfluidic systems that allows two (or more) different solutions to flow side-by-side in a channel without convective mixing. This fluid behavior can be used to pattern cell suspensions, particles, and treatments as well as to create chemical gradients. LFP is typically implemented using syringe pumps and, for this reason, is most effective in constant flow scenarios such as long-term gradient generation. However, the complexity of using syringe pumps for patterning cell suspensions typically makes it a less attractive option than other standard patterning methods. We present a passive microfluidic method that enables short-term LFP of multiple fluids using a single pipette and allows each sample to be loaded in any sequence, at any point in time relative to one another. The proposed method is well-suited for cell-based assays, reduces the complexity of LFP to be on a similar level as other cell patterning methods, can be scaled to include more than two streams of fluid, and enables arrays of individually addressable devices for LFP on a single chip.