We use two-phase micro- and millireactors where droplets of reagents are generated and transported as a string in a carrier continuous phase. These droplets can be seen as microreactors. Their small volume and high surface to volume ratio favours mixing, heat exchange and low reagent consumption, improving safety and economy. Moreover, hydrodynamics is facilitated by digitalizing the volumes: there is no distribution of residence time and no viscosity issues; additionally, the time-space equivalence allows a quantitative inline analysis with spectroscopy, thermography and optical techniques. Those devices offer great opportunities for transfer parameters and chemical kinetics data acquisition, as well as new material synthesis.