Experimental and theoretical study of selective protein deposition using focused micro laminar flows.

The present work describes an experimental method and design tools which enable the precise localization of an analyte, a few microns in width, both temporally and spatially using laminar flows and thus improves previous methods in hydrodynamic focusing. The technique is used to adsorb proteins to selected regions within a microfluidic device without any contamination of the surroundings and may serve in applications requiring selective conveying of other reagents. The regions not coated by proteins are modified with poly(ethylene glycol; PEG), known to efficiently resist protein and cell adhesion. Human endothelial and fibroblast cells are later introduced into the device selectively attaching to the protein coated regions and cultured for a few days. A simulation of the convection-diffusion characteristics of the system is presented and compared to the known T-sensor. The results reveal that, by proper design, reagents concentration may be kept nearly constant along the flow direction. This phenomenon is demonstrated here by achieving particularly precise patterning of cells but may be utilized for numerous other applications as well.