Embedded extrusion printing in yield-stress-fluid baths

Abstract

<h2>Summary</h2> Embedded extrusion printing, which prints inks in a support bath, is a promising approach for printing complex 3D structures using low-modulus, low-viscosity, or slow-solidifying inks. The key aspect of embedded extrusion printing is the supporting matrix. In particular, yield-stress fluids (YSFs) are the most suitable and extensively used support bath materials because of their rapid stress-induced solid–liquid transition. However, the rheological interactions between the YSF bath and flowing ink may lead to complex printing dynamics, and the effects of the YSF characteristics on the overall embedded printing process remain elusive. This review covers the recent state-of-the-art developments in the field of embedded extrusion printing in YSF baths, with a focus on the physical characteristics of the YSF support baths and the yielding transition mechanism by which they serve as <i>in situ</i> support for extruded inks. Additionally, the typical applications of this technology and its main challenges are discussed.