Substrate‐Independent Electrohydrodynamic Jet Printing with Dual‐Ring Electrostatic Focusing Structure

Abstract

Therefore, it has been widely used in the manufacturing of transistors, [4][5][6] micro/nano sensors, [7,8] flexible electronics, [9][10][11][12][13] and biomaterials, [14][15][16][17][18] etc. The E-Jet printing is a "pull" processing that uses an extra electric field to significantly improve resolution. When an appropriate electrical potential is applied to the extraction electrode at the outlet of a nozzle, a jet with a stable shape (Taylor cone) will be formed as a result of the balance of the electric field force, surface tension force, and gravity force. Different E-Jet printing modes (e.g., dropon-demand E-Jet, direct-writing E-Jet, and electrospray) can be realized by carefully adjusting the ink flux, the standoff height (nozzle-to-substrate distance), and the applied voltage, relying on a stable electrostatic field between the nozzle and the substrate. However, the E-Jet printing is hard to be applied in curved substrates due to the unstable electric field distribution caused by the variation of standoff height. Some scholars were concerned about this issue. Seong and his colleagues built the experimental setup to maintain a uniform electric field strength by implementing 3D movements of the nozzle to keep a constant standoff height during the printing. [19] Nevertheless, it is still difficult to control the jet with precision and consistency because the direction of the electric field varies with the relative position of the nozzle-substrate.In addition to curved substrates, the conductivity of the substrate is also an important factor affecting the E-Jet printing. Substrates with good electrical conductivity are often chosen because they can quickly direct residual charges away from the deposited droplets, thus improving the accuracy of the printed structures. In comparison, insulating substrates can severely degrade printing accuracy and resolution, and even interrupt the follow-on printing behavior. [20][21][22][23][24] That is because the polarization of the substrate under a strong electric field and the charge accumulation of the deposited droplets can change the electric field distribution between the substrate and the nozzle. Researchers have proposed ways to improve printing accuracy on insulating substrates. Dong and his coworkers presented an AC-pulse modulated E-Jet printing technology that can alternate the charge polarity of the consequent droplets to neutralize the residue charge on the substrate, which enables high-resolution printing of continuous patterns. [25] Wang et al. improved Electrohydrodynamic jet (E-Jet) printing is one of the most effective methods for fabricating micro/nanostructures due to its high-resolution, broad material adaptability, and simple process. However, printing high-resolution patterns on curved or insulated substrates still is of a great challenge because it is quite difficult to keep the electric field distribution stable between the nozzle and the substrate during the printing process. To address these issues, a dual-ring electrostatic focused electrohydro...

Recent Progress in Electrohydrodynamic Jet Printing for Printed Electronics: From 0D to 3D Materials

“…Zero-dimensional materials, also referred to as quantum dot (0D) materials, have the capacity to modify their optical properties depending on the size of the material, allowing for large-scale production while maintaining low cost [52]. The result is a steady and efficient emitter of almost any wavelength after decades of research and development.…”

“…Instead of pushing the printing material out of the nozzle like traditional printing methods, EHD jet printing uses high electrical fields to pull the material out. EHD printing can create precise micro-and nano-manufactured products [52][53][54][55]. By applying an electric potential between the nozzle and substrate, charged particles gather at the liquid-air interface, causing the meniscus to transform into a conical shape known as the Taylor cone.…”

On the Stability of Electrohydrodynamic Jet Printing Using Poly(ethylene oxide) Solvent-Based Inks

“…Owing to its large material versatility, this technology has been used for the production of a plethora of materials for a wide range of applications, from printed electronics [15] to batteries [16,17] and tissue engineering [18], among others [19]. Recently, breakthrough progress in the electrostatic control of the jet's positioning during its travel to the collector has further pushed the potential of this technology for commercial applications [20][21][22][23][24]. In particular, the use of jet-deflecting electrodes allows ultrafast printing by electrostatically stirring the EHD jet [20].…”

Flexible Patterned Electrohydrodynamic Jet Printing Using Orthogonal Deflection Electrodes

“…In our previous work, we introduced a dual-ring electrostatic-focused electrohydrodynamic jet (DEFEJ) printing method . In this method, we utilize a metal microtip with a radius of curvature (ROC) of several micrometers as the printing tip, which is placed in a conductive dual-ring structure to form a built-in focusing electric field and drive the Taylor cone.…”