A reactor-like spinneret used in 3D printing alginate hollow fiber: a numerical study of morphological evolution

Abstract

In this paper, a reactor-like spinneret is proposed to generate a continuous hollow hydrogel fiber. In order to reliably control the deforming dynamics, the components of the spinneret are standardized in order to ease the online observation of morphological evolution. We found that not only did a co-flow occur in the tubular space, but a relatively large shrinkage of the shell layer at the outlet also occurred. Whereupon a weak coupling of the velocity field and diffusion-reacting co-flow was developed to describe the monitored co-flow morphology and to simulate the intermediate state of the concentration field, as well as to calculate the shrinkage profile with an integral formula. And a critical isogram [G]cri was determined to correspond to the morphological segmental feature, to trigger gelation and shrinkage as a threshold of solubility and the integral upper limit of the shrinkage region. Experimental evidence indicates that: the simulation is able to effectively predict the inner diameter of the hollow fiber; the transient inner diameter of the fiber at the outlet is expanded by approximately 70 μm (co-flow distance = 15 mm) as compared to the initial fluid dynamics value, and that the relative mean error of the simulated inner diameter was less than 8%. The proposed study provides deeper insight into the printing of hollow fibers and other gelling processes which utilize a reactor-like spinneret.

Advances in Coaxial Additive Manufacturing and Applications

“…Figure 7d depicts a custom‐made coaxial spinneret developed by Li et al. [ 35 ] that was used to print gelatin‐alginate hollow fibers. This spinneret was made of four different parts represented in Figure 7d(ii): an inner nozzle, an outer nozzle that was 5 mm shorter than the inner one, a T‐fitting and a quartz tube use to make the outer needle as long as the inner one, forming a tube‐shaped reactor.…”

“…For instance, Li et al. [ 35 ] modelled the morphological evolution of the alginate hollow fibers 3D printed using a reactor‐like spinneret. Thanks to the rotational symmetry of the object, they were able to minimize the difficulty of the problem by considering a simplified axisymmetric 2D problems (the fibers were considered as rectangles and not cylinders).…”

“…Adapted with permission. [ 35 ] Copyright 2016, Royal Society of Chemistry; e) schematic representation of a coaxial needle for the extrusion of alginate fibers. Adapted with permission.…”

“…Simulations are not only useful to simulate the velocity and pressure profiles, but also are used to predict the interaction of the materials after deposition. For instance, Li et al [35] modelled the morphological evolution of the alginate hollow fibers 3D to print hydrogel tubes. Adapted with permission.…”

A novel method for fabricating engineered structures with branched micro-channel using hollow hydrogel fibers

“…11,12 Many studies have investigated strategies to obtain the branched micro-channels in engineered constructs. [13][14][15][16] 3D printed rigid filament networks have been used as a cytocompatible sacrificial template to generate cylindrical networks with branched channel in a bulk gel.…”