Ink-Bath Interactions in Embedded Ink Writing for Producing Functional Parts

Abstract

Embedded ink writing (EIW) is an emerging 3D printing technique that is extensively applied for a variety of engineering applications. This technique is featured by printing a liquid functional ink within a yield-stress fluid bath. Due to the selection of ink and bath materials with different hydrophilicity and hydrophobicity, diverse ink-bath interactions occur that affect the filament formation in EIW. In this work, the interrelationships between ink-bath interactions and three major physical phenomena (including filament diffusion, shrinkage, and breakage) are experimentally and systematically investigated. Several key parameters, such as interfacial tension between ink and bath materials, ink's elasticity, and bath's yield stress, significantly affect the morphology and/or geometry of as-printed filaments. Based on the obtained knowledge, a functional index finger is printed, which demonstrates a good grasping capability in a robotic hand system.