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

Abstract

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.

Toughening elastomers via microstructured thermoplastic fibers with sacrificial bonds and hidden lengths

“…The mechanical performance of the composite may also depend on the fiber-matrix adhesion and matrix properties which will deserve further investigations. Instability-assisted 3D printing [27,28,45,46], electrospinning [47][48][49] and melt electrowriting [50,51] provide the opportunity for the miniaturization of the microstructured fiber to accommodate different indenter sizes in real-world applications. The transparency of the composite materials can be improved by matching the refractive indexes of the fiber and the elastomer matrix for applications that require high optical transparency [26].…”

Electrohydrodynamics of droplets and jets in multiphase microsystems

“…The existence of a nearby plate not only interferes with the generated electric field, but also decelerates the jet approaching the plate. 141,147,148 For spinnable liquids, the interplay between the inertial and the viscous effect can be overturned as the nozzle-to-plate distance reduces, and other unstable modes, for instance, coiling instability, can occur. 141,147,148 A viscous thin liquid filament can exhibit a coiling instability, also known as ''liquid rope coiling'', which arises from an axial compressive stress that bends the jet.…”

“…141,147,148 For spinnable liquids, the interplay between the inertial and the viscous effect can be overturned as the nozzle-to-plate distance reduces, and other unstable modes, for instance, coiling instability, can occur. 141,147,148 A viscous thin liquid filament can exhibit a coiling instability, also known as ''liquid rope coiling'', which arises from an axial compressive stress that bends the jet. [149][150][151] The compressive stress can result from the deceleration of the jet along the axial direction, for example, when a liquid jet encounters a substrate.…”