Facile Control of Liquid-Rope Coiling With Tunable Electric Field Configuration

Liquid-rope coiling occurs when a thin jet of viscous fluid falls from a sufficient height onto a rigid substrate. Coiling can also be induced by an electric field, and this precise control over coiling has inspired alternative applications in direct writing, such as the printing of nano-objects and the mixing of viscous fluids. However, the physical mechanism of electric field-assisted coiling remains inadequately understood, challenging the optimization of the design of printing setups. We identify the subtle role of the electric field profile on the jet morphology and the onset of coiling, especially the height, by modifying the electrode configuration for controlling an electrified jet. Based on our finding, we demonstrate that the viscous coiling effect can be either induced or suppressed by changing the configuration of the electrodes, which tunes the electric field profile. The exquisite control of the coiling of viscous fluids can enhance applications that require dispensing of viscous liquids and on-demand direct writing for a wide range of working conditions and various printed patterns.