Fig. 1. An illustration demonstrating the challenges for addressing boundary conditions in microfluidics-based microvascular models (a–c), along with our solution (d). (a) A single-inlet, single-outlet network created by adding a bounding channel that connects all dead-ends. As there is no direct control over the bounding connections, the resulting model exhibits irregular flow. (b) A multi-inlet, multi-outlet network created by attaching a series of peripheral pumps to provide necessary boundary conditions, which is impractical for 3D, non-planar networks. (c) A single-inlet, single-outlet network effectively eliminates flow through a majority of branches by blocking most terminations (red X's). (d) Our solution constructs connections between network terminations and pre-defined feeders to enforce the appropriate boundary conditions and thus desired flow properties in both 2D and 3D networks.