A Microscale 3D Printing Based on the Electric-Field-Driven Jet

Abstract

This study presents a novel microscale three-dimensional (3D) printing based on the electric-field-driven (EFD) jet. Differing from the traditional electrohydrodynamic jet printing with two counter electrodes, the EFD jet 3D printing forms electric field between the nozzle electrode and the top surface of the substrate or printed structure only using a single potential by the nozzle electrode. The numerical simulations and experimental studies were carried out to verify the capabilities and advantages of the proposed approach, which includes the suitability of substrates, the potentials of the conformal printing, and the large size 3D printing. Besides, considering the high-resolution and high-efficiency printing of various materials with different viscosities, two working modes, including the pulsed cone-jet mode and the continuous cone-jet mode, were proposed and investigated by the CCD camera. Finally, several typical printed structures were provided to demonstrate the feasibility of the proposed technology for microscale two-dimensional patterning and macro/micro-3D structure fabrication. As a conclusion, this breakthrough technique provides a high-efficiency and high-resolution 3D printing technique enabling direct-write, noncontact, and additive patterning at microscale for a variety of ink systems and melted polymer materials, especially for the multiscale and multimaterial additive manufacturing.

Keywords: 3D printing; electric-field-driven; multimaterial; multiscale.

FIG. 1.

The EFD jet 3D printing of (a) the system setup schematic. The working principle of (b) the electrostatic induction between the nozzle and the top surface of substrate (c) stresses acting on the meniscus, and (d) the electrostatic induction between the nozzle and the printed structure. Two working modes of (e) the pulsed cone-jet mode and (f) the continuous cone-jet mode. 3D, three dimensional; EFD, electric-field-driven.

FIG. 2.

The simulation of electric field and the experiment of ejection behavior on: (a, e) copper substrate with thickness of 2 mm; (b, f) silicon substrate with thickness of 0.5 mm; (c, g) glass substrate with thickness of 1.2 mm; (d) the electric field on the glass substrate of 1.2 mm thickness with a printed multilayer structure of 500 μm height; (h, i) the printing behavior of multilayer structure of PCL polymer. PCL, polycaprolactone.

FIG. 3.

The ejection process and printed patterns in: (a–c) and (g) the pulsed cone-jet mode; (d–f) and (h) the continuous cone-jet mode; (i–m) the printing process for a 3D circular platform, in which (j) the Taylor cone in the pulsed cone-jet mode with different printed height [upper and lower figures are high-magnification views of (i) and (k), respectively], and (m) a 3D circular platform with height of 5.5 mm, bottom diameter of 18 mm, and top diameter of 11 mm.

FIG. 4.

Silver grid patterns with (a) line width of 8 μm and spacing of 150 μm on the glass substrate; (b) line width of 10 μm and spacing of 150 μm on the silicon substrate; (c) a 3D structure electronics; and (d) the conductive wires on the top surface.

FIG. 5.

The 3D structures of PCL: (a, b) a wall structure with high-aspect ratio of 20; (c–e) a high-aspect-ratio grid structure; (f–h) a tissue engineering scaffold; (i, j) a polylactic acid helical structure with a line width of 65 μm printed on a glass bar with a diameter of 4 mm.