Multiple interactions between microfluidic droplets and on-chip pneumatic valves

Microfluidic droplet arrays potentially allow to carry out assays involving complex workflows at the single-cell level. In recent developments [e.g. (Jeong et al. in Lab Chip 16:1698, 2016)], each droplet of the array can be addressed individually thanks to on-chip pneumatic valves. In this experimental and theoretical work, we investigate the multiple interaction regimes between one or several droplets and a pneumatic valve. In particular, two main trapping modes are characterized, with very distinct flow features. We quantify the potentially huge increase of hydrodynamic resistance induced by the droplet/valve interaction. Finally, we rationalize the main transitions between trapped and non-trapped regimes through a generic theoretical model of the balance between capillary, hydrodynamic and elastic forces.

Automated summary

In this study, the interaction between microfluidic droplets and pneumatic valves in droplet arrays was investigated experimentally and theoretically. Two main trapping modes were characterized, and the significant increase of hydrodynamic resistance induced by the droplet/valve interaction was quantified. Transitions between trapped and non-trapped regimes were rationalized using a generic theoretical model.