Fig.2.

Methods for controlling oxygen in microphysiological systems (MPS) to study cellular responses. (a) Gas diffusion used to generate an oxygen gradient across a layer of Madin-Darby Canine Kidney (MDCK) cells. Reproduced from Ref. 27 with permission from The Royal Society of Chemistry, copyright 2010. (b) Gas filled channels create an oxygen gradient from 0% to 20% oxygen. Reproduced from Ref. ¹³⁴ with permission from The Royal Society of Chemistry, copyright 2012. (c) Oxygen scavengers in leftmost chemical reaction channel remove oxygen, while oxygen generators in the rightmost channel create a gradient of oxygen between the chemical reaction channels, inside the cell culture channel. Reproduced from Ref. 22 with permission from The Royal Society of Chemistry, copyright 2011. (d) Oxygen diffused through collagen hydrogels of various height and fiber density to create oxygen gradients. Reproduced from Ref. 85 with permission from The Royal Society of Chemistry, copyright 2017. (e) Cells consume oxygen inside the liver MPS to create oxygen-limited environment. Reproduced from Ref. 49 with permission from The Royal Society of Chemistry, copyright 2010. (f) Transwell insert contains Parylene coating to prevent environmental oxygen from contaminating inner hypoxic device. Reproduced from Ref. 115 with permission from The Royal Society of Chemistry, copyright 2010.