Gravity-driven preprogrammed microfluidic recirculation system for parallel biosensing of cell behaviors

Fluid recirculation is an important function for organ-on-chip and microfluidic applications. For a systematic analysis, simultaneously applying multi-flow conditions in parallel channels is essential. However, control of parallel recirculation flows without using dynamic off-chip controllers that can drastically simplify device operation has been rarely implemented. In this study, we develop a microfluidic recirculation system driven only by water-head pressures. The pressures generated by reservoirs with <500 mL water volumes drive the system and recirculate <500 mu L cell culture media volumes. The system realizes media recirculation in its four parallel channels with pulsatile and constant flows in a preprogrammed manner. The system, which consists of oscillator and cell culture modules, controls the flow rates and shear stress in wide ranges of 0.06-144 mu L min(-1) and 0.004-9.6 dyn cm(-2), respectively. For pulsatile flows, the pulse period is independent of the flow rate and varies in the range of 0.7-13.0 s. To demonstrate the utility of the device, the systematic and parallel analysis of endothelial cell elongation response to different fluidic shearing patterns is performed. In addition, the culture of myoblasts is illustrated, and myotube formation is successfully obtained for 8 days.

Automated summary

In this study, a microfluidic recirculation system driven by water-head pressures was developed, which enables media recirculation in parallel channels with pulsatile and constant flows. The system allows control of flow rates and shear stress, and can be used for systematic and parallel analysis of cell response to fluidic shearing patterns.