Abstract: The present disclosure generally relates to compositions, methods, sorters, systems, devices and uses for screening for bioactive substances in emulsion droplets. In some embodiments, the compositions are a continuous phase formulation for stable emulsions, In some embodiments, the methods are for preparing a monodisperse polyethylene glycol acrylamide (PEGA) co-polymer resin, or for preparing a core-shell bead. In some embodiments, the systems and devices include a sorter, comprising an inlet channel, first and second outlet channels meeting the inlet channel at a junction, and first and second electrodes proximate respective first and second sides of the junction sorter.