Figure 1

The experimental platform, consisting of a microfluidic device, a flow channel placed in a stage incubator to control the oxygen concentration in a cell culture medium, a roller pump, a reservoir for the cell culture medium, gas blenders, and humidifier bottles. The oxygen and carbon dioxide concentrations of the gas mixtures were adjusted by mixing with nitrogen. The gas mixtures were humidified by bubbling through the humidifier bottles before being supplied to the gas channels in the microfluidic device. The cell culture medium was circulated by the roller pump: medium was drawn from the reservoir, supplied to the flow channels and the media channels in the microfluidic device, and then returned to the reservoir. Red and blue arrows indicate the flow directions of the cell culture medium and gas mixtures, respectively. The upper right figure is a photograph of the device and the flow channel placed in the stage incubator.