Spatially Resolved Measurement of Dissolved Oxygen in Multistream Microfluidic Devices

Dissolved oxygen (DO) is an important parameter with significant effect on cellular development and function. Micron-scale laminar flow and hydrodynamic focusing provide ideal tools for the generation of controlled chemical micro-environments and their application as stimuli to cells. In this paper, we demonstrate the generation and characterization of multistream laminar flow and hydrodynamically focused sample streams with defined dissolved oxygen concentrations on chip. A solid-state oxygen sensor layer was integrated into PDMS-based microchannels and calibrated. Several combinations of sample and buffer streams with concentrations ranging from 0 to 34 mg/l DO were generated and measured for up to three independent parallel flow streams. In addition, diffusion-based stream broadening measured with the sensor was used to determine the coefficient of diffusion of O₂ in the flow medium. The devices have the potential to provide novel insights into cell biology and improve the relevance of in vitro cell assays.