Non-invasive characterization of dissolved oxygen dynamics in water-in-oil droplet microfluidics – Towards 3d micro tumor spheroids for high throughput cancer drug screening
Oxygenation is a key parameter in tumor spheroid culturing. This work reports on the study of oxygen concentration and gas exchange dynamics in two-phase microfluidic droplet systems. Initial measurements of oxygen in single, oil-covered aqueous droplets in micro-wells show the feasibility of droplet-based sensing. We further introduce on-chip generation and trapping of individual droplets with controlled dissolved oxygen concentrations. Luminescence-based optical sensing is used to characterize the time-resolved dynamics of gas exchange between surrounding oil and micro-droplets where both phases exhibit pre-defined oxygen concentrations. This will help to determine suitable fluid combinations for oxygen-sensitive applications, such as high-throughput screening of drugs on micro-spheroids.