All-aqueous emulsions are aqueous droplets dispersed in another immiscible aqueous phase.Unlike typical emulsions containing both oil and aqueous phases,the all-aqueous emulsions are free of organic solvents; thus they are non-toxic and recyclable [1].All-aqueous emulsions are also excellent liquid templates for partition of cells and for the fabrication of hydrogel matrix.Despite these advantages in practical applications,precise manipulation of the emulsion droplets remains challenging,due to the low interfacial tension and high viscosity of the aqueous two phases system (ATPS).In this abstract,we report the controlled fabrication of water-in-water-in-water (w/w/w) double emulsion by integrating the capillary microfluidic device with an electrospay technique.A water-in-water (w/w) jet is produced in a single emulsion device and charged using a direct current power supply.As the charged jet is sprayed into air,it breaks up into droplets.These droplets eventually fall into a third aqueous phase,forming w/w/w double emulsions.By changing the applied voltage and the flow rates of the two phases,the structure and the size of the double emulsion can be tuned.The polydispersity of these droplets depends on the applied voltage [2].With these w/w/w double emulsions as liquid templates,the capsules with a core-shell structure are fabricated by gelation of the middle aqueous phase.We demonstrate the biocompatibility of the capsules by using them to encapsulatee yeast cells.Compared with the hydrogel matrix made of solid particles,the capsule with a thinner hydrogel wall promotes efficient exchange of oxygen and nutrients [3].This represents a first demonstration of hydrogel capsules fabricated using a combined approach of electrospray and all-aqueous emulsion-templating.