Figure 4. Schematic and validation of a microfluidic device capable of spatio-temporal oxygen control.

A. Image showing a magnified view of the completed microfluidic device used to oxygenate different regions of the brain. This device consists of 4 independent parts: the perfusion chamber, the PDMS membrane, the PDMS microfluidic channels, and a simple glass slide. The square shows the location where the measurements for C were taken. B. 10X image showing the 2 channels used for data collection with the 0.3 mm wall at the center of the image. Data from both sides of the image were collected. C. To test the spatial resolution of the device, the oxygen and Fura measurements were taken at fixed positions across the microchannels. During the experiments, one channel is flowing 95% O₂ gas, while the adjacent channel is flowing 0% O₂ gas. As shown in the graph, there is a steep change, in both oxygen and Fura, in the measurements obtained from the 2 adjacent channels. Dashed lines indicate the wall's boundaries.