Additive manufacturing solidification methodologies for ink formulation

With the burgeoning interest in 3D printing for complex and high-resolution patterned devices, ink formulation plays a vital role for its successful utilization in various application in energy, structural and medical. This review paper will aid readers in the field of 3D printing in making an informed evaluation of the current 3D printing technologies available for practical utilization. A huge challenge in 3D printing ink formulations is in its green part strength. 3D printing technology of viscoelastic materials involves multiple steps of which, the solidification step affects the structure and functionality of the product. We have examined the different ink formulations used in 3D Printing-related journal papers and their solidification mechanisms have been organized and summarized into this review paper. One of the most commonly used solidification mechanisms is solvent-assisted drying. Although it often results in brittle green parts, solvent-based inks are versatile, economical and relatively environmentally friendly. To improve the structural integrity of viscoelastic inks, in-situ curing methods (ultra-violet light assisted, thermal assisted etc.) are utilized to increase the yield strength of the 3D printed structures. The progress, advantages, and disadvantages in three main solidification methods (namely solvent-assisted drying, ultraviolet light-assisted curing and thermal-assisted curing) for 3D printing (in particular, Direct Ink Writing (DIW)) will be discussed. A proposed outlook is also given to shade a light on the importance in selecting proper methods and made a guideline for matching the materials and applications library.