Note: A versatile 3D-printed droplet-on-demand generator.

A versatile 3D-printed droplet-on-demand generator is presented for laboratory use in droplet impact and similar experiments. The design described and tested in the present work is modeled off of an existing design [Harris et al., Exp. Fluids 56, 83 (2015)] but is tested with an extended range of working fluids, and the manufacturing process is greatly simplified by 3D-printing the principal components. The present device is tested with de-ionized water and water-glycerol mixtures and was reliably able to produce single droplets-on-demand of diameters 0.65-1.32 mm with an overall variability of less than 1%. The computer-aided design (CAD) files, parts list, sample software, and circuit layout are available with this note, allowing for the device to be readily reproduced or adapted for a wide range of experimental applications.