“…Microdroplet technology, known as droplet microfluidics, is an emerging microfluidic strategy, which can generate, manipulate and analyze discrete droplets with a volume of nanoliters or below. 1–3 Droplet microfluidics has been widely used in various fields, such as drug delivery, 4,5 chemical synthesis, 6,7 microreactors, 8,9 bioassays 10,11 and cell analysis, 12–14 in which the controllable generation of microdroplets is of vital importance for the following application process. 15 Thus, on-demand droplet generation over a wide size range with a miniaturized and versatile platform will facilitate the wide use of droplet microfluidics in various research and application fields.…”