Advances in Coaxial Additive Manufacturing and Applications

Abstract

Coaxial additive manufacturing (AM) is an emerging technology involving the simultaneous deposition of two or more materials with a common longitudinal axis. It has the potential to overcome the disadvantages associated with conventional single‐material AM for the production of core‐shell or multi‐core‐shell multimaterial structures. The coaxial AM techniques can be classified into extrusion and material jetting technologies. The extrusion‐based technologies rely on the co‐extrusion of multiple materials through a coaxial nozzle whereas the material jetting technologies are based on the introduction of a high voltage electric field between a coaxial nozzle and a grounded collector plate. This review is aimed to provide a comprehensive overview of multimaterial coaxial AM, including the technologies, nozzle designs, materials, and applications. The advances in coaxial AM and the benefits of this novel technology in various fields are highlighted. For instance, in biomedicine coaxial AM offers an exciting alternative to single‐material bioprinting for the fabrication of bio‐scaffolds and vascular networks as well as for tissue engineering and cell encapsulations. Coaxial AM is also a subject of growing interest in the fields of flexible sensors, e‐textiles, and printed electronics. Perspectives on the limitations, existing challenges, opportunities, and future directions for further development are also provided.

Sustainable Sources of Raw Materials for Additive Manufacturing of Bone‐Substituting Biomaterials

“…Currently, the coaxial nozzle‐based AM technique is mostly utilized for the fabrication of vascular networks, microfluidic applications, or flexible, stretchable, conductive, and piezoelectric sensors. [ 237 ] In situ DIW involving laser for selectively melting or sintering during the extrusion of ink material can be utilized. Laser‐assisted DIW has been reported for the fabrication of 3D structures made of a silver ink (Figure 7j).…”

“…i) A schematic illustration of coaxial 3D printing of multimaterial (Adapted with permission. [ 237 ] Copyright 2021, Wiley‐VCH GmbH) with SEM images of TCP (shell) and polycaprolactone (core) composite scaffold (Adapted with permission. [ 236 ] Copyright 2019, Elsevier).…”

“…h) A schematic illustration of extrusion-based AM using an ink containing multiple materials (e.g., Ti6Al4V and eggshell powder) and an SEM image of Ti6Al4V-CaO composite scaffolds (original research reported for the first time here). i) A schematic illustration of coaxial 3D printing of multimaterial (Adapted with permission [237]. Copyright 2021, Wiley-VCH GmbH) with SEM images of TCP (shell) and polycaprolactone (core) composite scaffold (Adapted with permission [236].…”

3D Printing‐Enabled Design and Manufacturing Strategies for Batteries: A Review

“…[120,167] As one trial, coaxial printing, typically composed of an outer and an inner needle, allows for printing multi-material potentially useful for assembling multiple battery components during fabrications. [168] For example, Golodnitsky et al fabricated all-SSEs sandwiched between electrodes and their core component of current collectors using a coaxial fabrication method, as shown in Figure 12a 1 . [120] While their primary focus was on the electrolyte composed of LiTFSI, PEO, and PLA for enhanced mechanical properties, they carried out characterization methods through SEM, mass spectroscopy, and differential scanning calorimetry (DSC), with the electrochemical impedance spectroscopy (EIS) and charge and discharge cycles demonstrated in Figure 12a 2 ,a 3 .…”

Progress of Additive Manufacturing Technology and Its Medical Applications

“…[81], as with all types of bioprinting it faces challenges in formulating the ink to possess simultaneously non-cytotoxicity, adequate viscosity, dimensional stability, and more importantly the environment for continuous cell growth [78]. In a recent development, a multiple channeled AM method was developed to fabricate functional human tissues and organs in which a core-shell structure (blood vessel or multilevel fluidic channels made with hydrogel) and macro/micro encapsulation were combined to render the construct biochemically and biomechanically functional [82]. However, the calcium-alginate hydrogels used in this technique were unable to produce long vascular networks since the bioprinted structure is inherently weak when subjected to stress.…”