A 3D printed screw-and-nut based droplet generator with facile and precise droplet size controllability

Herein, we present the fabrication of a novel vertical T-junction based droplet generator using a desktop 3D printer and the production of a variety of size of polymer particles by tuning the vertical T-junction gap height (h(g)) with ease. The droplet generator device consists of two main components: an internal thread nut with a vertical T-junction droplet generator unit, and a screw with an external thread for adjusting h(g). The two components were fabricated by a 3D printer and assembled simply by a bolt-and-nut combination. The clockwise or counter-clockwise rotation of the screw is converted into the downward and upward linear motion of the screw, adjusting the h(g) value. The h(g) value can be tuned precisely from 0 to 750 mu m by designing 75 control teeth on the top of the screw. The size of the produced droplets is proportional to the h(g) value. The size range of the droplets was 39-1404 mu m, when h(g) changed from 20 to 200 mu m. We synthesized poly(ethylene glycol) diacrylate (PEGDA) particles using the droplet as a reactor, and accordingly the PEGDA particle size could be controlled. Our proposed 3D printed droplet generator is rapid, simple and cost-effective to be fabricated without need of lithographic processes.