Orientation-independent bubble trap with internal partition for robust operation of microfluidic systems

A new monolithic bubble trap has been developed with a unique, orientation-independent design. The bubble trap has a spherical cavity and a central partition with internal passages that eliminate air bubbles effectively for extended periods of time. Flow testing was performed in a closed-loop microfluidic system to demonstrate effectiveness and robustness of the bubble trap. Flow rate was continually monitored on a stationary benchtop and also in simulated microgravity conditions on a 3-D random positioning machine. Data collected from flow sensors placed fore and aft of the bubble trap confirmed that randomly occurring bubbles were effectively eliminated by the trap throughout 24 hour closed-loop perfusion tests. To highlight the orientation-independent benefit of the bubble trap in a specific application of interest, continuous-flow experiments were conducted using human umbilical vein endothelial cells in a closed-loop microfluidic system. The bubble trap successfully protected the integrity of confluent layers that otherwise suffered from cell detachment without the trap. Image analysis showed that random orientation reduced directional alignment of cell nuclei, relative to baseline experiments performed under normal gravity.