Cone-jet regime in electrospray: A comprehensive review

Cone jet is a very important and promising mean in electrohydrodynamic atomization or electrospray, where a liquid cone forms at the end of a capillary tube at a rational range of potential and flow rate and a permanent, stable, and thin jet emerges from the cone tip and further disintegrates into plenty of fine drops. Owing to several advantages of uniform and microscale drop size, high-charge density, and precise trajectory control, the cone-jet electrospray effectively meets a wide range of application requirements. This work provides a critical review the recent experiments, theories, analysis, and numerical simulations concerning the formation and evolution of Taylor cone and cone jet, as well as the subsequent jet breakup and drops generation. Our aim is to offer a comprehensive understanding of the underlying physics of the process of cone jet, including the conditions for the formation and the stable operation of the cone jet, and the universal scaling laws governing minimum flow rate, drop size, and electric current, as well as the instability of cone jet. In addition, the coaxial Taylor cone jets and the recent numerical studies on cone-jet dynamics are also briefly reviewed.