Generation of water-in-oil and oil-in-water microdroplets in polyester-toner microfluidic devices

•Fabrication of polyester-toner T-junction devices.•Generation of W/O and O/W droplets in the same device without surface treatments.•Production of highly monodisperse W/O or O/W emulsions.•Fast (<10 min) and low cost (∼$0.10 per device) fabrication procedure.

This paper demonstrates that disposable polyester-toner microfluidic devices are suitable to produce either water-in-oil (W/O) or oil-in-water (O/W) droplets without using any surface treatment of the microchannels walls. Highly monodisperse W/O and O/W emulsions were generated in T-junction microdevices by simply adding appropriate surfactants to the continuous phase. The dispersion in size of droplets generated at frequencies up to 500 Hz was always less than about 2% over time intervals of a couple of hours.