3D printing of droplet microfluidic devices: principles, wetting control, scale-up, and beyond

hydraulic balancing and unit-resistor strategies that preserve monodispersity across arrays, and outline selective surface treatments and multi-material printing approaches for achieving durable wettability patterns. Finally, we highlight AI/digital-twin workflows for predictive design and adaptive control, and map pathways toward standardized, manufacturable devices. These principles offer a conservative, application-oriented blueprint for 3D-printed droplet microfluidic devices.