Computational study of extrusion bioprinting with jammed gelatin microgel-based composite ink

Abstract

Abstract Material extrusion, a filament-based three-dimensional (3D) bioprinting technique, is commonly adopted to fabricate many complex constructs for its high efficiency, compatibility with a variety of biomaterials, and easy realization. During extrusion bioprinting, the morphology (including the shape and size) of extruded filaments is of great interest since the filaments are the basic building blocks for printed 3D structures and the filament morphology determines the printing resolution, surface quality, and part mechanical strength. The objective of this study is to computationally analyze the printing performance of the jammed gelatin microgel-based composite ink during extrusion in terms of the filament cross-sectional morphology and the influence of ink yield-stress fluid property on the structural printability. As seen from the rheological measurements, the jammed gelatin microgel composite ink is a viscoplastic fluid with the shear-thinning property, and its yield-stress fluid property enables it for self-supported printing applications. The ink printing process has been computationally modeled by using a fitted Herschel–Bulkley model to simulate the behavior of the jammed gelatin microgel composite ink for the first time, resulting in good modeling performance. In particular, the filament cross-sectional morphology under different printing conditions has been satisfactorily modeled. It is found that the cross-sectional shape turns flat rectangular under a small normalized gap distance (less than 0.6). Furthermore, the achievable maximum length (without collapse) of the jammed gelatin microgel-based composite ink, deposited both between two supporting substrates and over a supporting substrate, has been satisfactorily estimated.