Confocal microscopic image of water-in-oil droplets (a) and agarose-in-oil gel beads (b). The droplet size distribution was measured by dynamic light scattering. Inset: Histogram of the droplet size distribution obtained using a 4-μm (a) and 15-μm (b) nozzle orifice diameter. The mean diameter is 1.31 μm, with a volume of 1.2 fL (a) and 1.55 μm, with a volume of 1.9 fL (b). The coefficients of variation (CV) is 11.73% (a) and 15.09% (b). Scale bar: 5 μm (a) and 10 μm (b).