Scaling up microdroplet production with post-array devices.

Microfluidic systems capable of generating uniform droplets are gaining attention in food, cosmetics, biochemical, and materials applications. While conventional shear- or interfacial tension-driven nozzle devices can generate highly monodisperse droplets (CV < 5%), their scalability is limited by complex flow designs and clogging. Post-array devices have recently emerged as a high-throughput alternative, producing quasi-monodisperse droplets (CV > 12%) by sequentially breaking larger droplets using micro-post structures. These devices offer shear-dependent tunability of droplet sizes, greater resistance to clogging, and scalability. Notably, droplet size is strongly influenced by the dispersed phase fraction, enabling potential decoupling of droplet size and dispersed phase fraction. This study reviews the principles and performance of post-array devices, compares them with other droplet generation methods, and examines their similarities to droplet splitting in T-junctions and premix membrane emulsification. Challenges such as improving droplet uniformity and miniaturization are also discussed to highlight the potential of post-array systems for practical emulsification applications.