Microfluidic generation and dynamically switching of oxygen gradients applied to the observation of cell aerotactic behaviour

We propose a simple but reliable technology for the generation of oxygen gradient in microfluidic devices, which is useful for cell aerotaxis study. The technology is based on single layer patterning of polydimethylsiloxane (PDMS) and integration of a thin layer polyvinylidene chloride (PVDC). The PDMS layer was patterned to define a cell chamber embedded by two micro-channels, whereas the PVDC layer acts as barrier to prevent the diffusion of gas outside into the layer, thus forcing gas to diffuse along the PDMS layer. As a result, a linear oxygen gradient in the cell chamber can be established by controlling the gas contents inside the two micro-channels. By using 3-way valves, such a linear gradient could be changed from one state to another. To demonstrate the application potential of this approach, we used this device in the study of the aerotactic behaviour of magnetospirillum sp. strain AMB-1 and observed a stable and reversible cell migration by changing the gas distribution in the cell chamber. This system should be useful for better understanding of cell aerotactic mechanism.