FIG. 4.

Modeling oxygen transport within DIP chamber constructs. (a) The DIP chamber construct geometry was discretized into a hexahedral finite element mesh with 25,920 elements that had converged to a stable solution. (b) When we assume an oxygen molecule hydrodynamic radius of 159 × 10⁻⁹ mm, diffusion coefficient D_O2 = 2.286 × 10⁻³ mm²/s (Supplemental Material), and an initial oxygen concentration of zero, E- and E+I-circulated constructs equilibrate to medium oxygen levels in approximately 48 h. Both axial and longitudinal cross sections are presented for selected time points in E-circulated (c) and E+I-circulated (d) models. According to the model, perfusion through the central port of E+I-circulated constructs increased the rate of oxygen diffusion into the construct volume. After 18 h of perfusion, nearly 91% of the E+I-circulated construct is equilibrated to medium O₂ concentration compared to 83% of the E-circulated volume.