2024 | Paula G. Saiz, Ander Reizabal, Jose Luis Vilas-Vilela, Paul D. Dalton, and Senentxu Lanceros-Mendez
Melt electrowriting (MEW) is an emerging additive manufacturing (AM) technology that enables the precise deposition of continuous polymeric microfibers, allowing for the creation of high-resolution constructs. Recent advancements have introduced active properties or additional functionalities through novel polymer processing strategies, functional fillers, post-processing techniques, and combinations with other manufacturing methods. While extensively explored in biomedical applications, MEW's potential in other fields remains untapped. This review explores MEW's characteristics from a materials science perspective, emphasizing the diverse range of materials and composites processed by this technique and their current and potential applications. Additionally, it highlights the prospects offered by post-printing processing techniques and the synergy achieved by combining MEW with other manufacturing methods. The review aims to inspire research groups across various fields to leverage this technology for innovative endeavors.
MEW, also known as near-field melt electrospinning or melt electrospinning writing, is an electrohydrodynamic (EHD) technology that enables the fabrication of high-resolution 3D porous macrostructures in a solvent-free mode. It combines thermal energy and electrical forces to control the extrusion of molten polymers through a nozzle, forming well-ordered continuous micrometric fibers upon solidification. The basic configuration of MEW devices includes a heated polymer feeding system, a three-axis positioning configuration, and a high-voltage source. The electric field generated between the printhead and the collector induces charges on the molten drop, forming a Taylor Cone, which facilitates the deposition of well-rounded fibers. The applied charges minimize EHD instabilities, allowing for precise control of fiber morphology and shape. By fine-tuning parameters such as temperature, voltage, and collector-head distance, MEW can produce highly porous structures with controlled mechanical properties and cellular behavior. However, challenges remain, including scalability, accessibility, and materials processability, which are being addressed through advancements in device design and material processing.
Recent years have seen a significant expansion in the variety of polymers suitable for MEW, surpassing the landscape described in previous reviews. Polycaprolactone (PCL) remains the dominant polymer, known for its exceptional processability and biocompatibility. Other polymers, such as poly(lactic acid) (PLA) and its copolymers, have also been extensively investigated due to their biomedical applications. Water-soluble polymers like poly(2-ethyl-2-oxazoline) (PEtOx) and poly(2-ethyl-2-oxazone) (PEOz) have been explored for creating specialized structures like channels and drug release designs. Non-biodegradable polymers, such as polypropylene (PP) and thermoplastic polyurethanes (TPUs), have been processed to enhance mechanical properties and introduce unique functionalities. Shape memory polymers and liquid crystal elastomers (LCE) have also been processed to offer 4D functionality and temperature-responsive shape changes. Filament-drivenMelt electrowriting (MEW) is an emerging additive manufacturing (AM) technology that enables the precise deposition of continuous polymeric microfibers, allowing for the creation of high-resolution constructs. Recent advancements have introduced active properties or additional functionalities through novel polymer processing strategies, functional fillers, post-processing techniques, and combinations with other manufacturing methods. While extensively explored in biomedical applications, MEW's potential in other fields remains untapped. This review explores MEW's characteristics from a materials science perspective, emphasizing the diverse range of materials and composites processed by this technique and their current and potential applications. Additionally, it highlights the prospects offered by post-printing processing techniques and the synergy achieved by combining MEW with other manufacturing methods. The review aims to inspire research groups across various fields to leverage this technology for innovative endeavors.
MEW, also known as near-field melt electrospinning or melt electrospinning writing, is an electrohydrodynamic (EHD) technology that enables the fabrication of high-resolution 3D porous macrostructures in a solvent-free mode. It combines thermal energy and electrical forces to control the extrusion of molten polymers through a nozzle, forming well-ordered continuous micrometric fibers upon solidification. The basic configuration of MEW devices includes a heated polymer feeding system, a three-axis positioning configuration, and a high-voltage source. The electric field generated between the printhead and the collector induces charges on the molten drop, forming a Taylor Cone, which facilitates the deposition of well-rounded fibers. The applied charges minimize EHD instabilities, allowing for precise control of fiber morphology and shape. By fine-tuning parameters such as temperature, voltage, and collector-head distance, MEW can produce highly porous structures with controlled mechanical properties and cellular behavior. However, challenges remain, including scalability, accessibility, and materials processability, which are being addressed through advancements in device design and material processing.
Recent years have seen a significant expansion in the variety of polymers suitable for MEW, surpassing the landscape described in previous reviews. Polycaprolactone (PCL) remains the dominant polymer, known for its exceptional processability and biocompatibility. Other polymers, such as poly(lactic acid) (PLA) and its copolymers, have also been extensively investigated due to their biomedical applications. Water-soluble polymers like poly(2-ethyl-2-oxazoline) (PEtOx) and poly(2-ethyl-2-oxazone) (PEOz) have been explored for creating specialized structures like channels and drug release designs. Non-biodegradable polymers, such as polypropylene (PP) and thermoplastic polyurethanes (TPUs), have been processed to enhance mechanical properties and introduce unique functionalities. Shape memory polymers and liquid crystal elastomers (LCE) have also been processed to offer 4D functionality and temperature-responsive shape changes. Filament-driven