Rapid macromolecular synthesis in a microfluidic channel with an oscillating flap

This study explores a method of enhancing the rates of macromolecular transport through a microchannel by introducing an oscillating mechanical flap in the fluidic system. A theoretical model is developed to determine the enhancement of macromolecular transport to a reaction site located along the channel surface. A numerical analysis is performed by considering a hinged flap located on the top or bottom walls of the channel. An order of magnitude analysis is conducted to estimate the reaction time which is bounded by the diffusion and the flow residence time. The period of oscillation is chosen to match the surface reaction time. The values of the characteristic flow variables adopted in this study, are representative of typical biomolecular transport processes confined to microscale geometries. With background flow, the results of the numerical analysis show that the mechanical actuator behaves like a miniature pump that drives a favorable gradient of macromolecules towards the surface reaction sites within an initial lapse of time. In a stagnant fluid, the results show that the moving flap behaves like a stirring agent bringing fluid with a higher concentration in contact with the reaction site and enhancing the surface concentration. In the latter case, the effect of the moving flap increases as the reaction progresses. The moving flap has the largest beneficial effect on surface concentration in the presence of a background flow when the position of the moving flap is along the top wall above the reaction site.