Challenges and Opportunities in 3D Printing of Biodegradable Medical Devices by Emerging Photopolymerization Techniques

Since the first report of 3D printed biodegradable structures by stereolithography, vat photopolymerization has shown great potential in the fabrication of medical implants and devices. Despite its superior printing quality and manufacturing speed, the development of biodegradable devices by this technique remains challenging. This results from the conflicting viscosity requirements for the printing resins, i.e., low viscosity is required for high-resolution 3D printing, whereas high viscosity is often needed to provide high mechanical strength. Recently emerging photopolymerization-based 3D printing techniques, including heat-assisted digital light processing (DLP) and volumetric printing, have brought new hope to the field. With its tolerance to high viscosity resins, heat-assisted DLP enables the fabrication of complex, personalizes architectures from biodegradable photopolymers that are not printable by conventional printing techniques. On the other hand, volumetric printing, which abandons the layer-by-layer printing principle and thus circumvents the dependence on low viscosity resins, could be highly beneficial for the 3D printing of biodegradable devices. This perspective evaluates the key challenges associated with biodegradable photopolymers used in the 3D printing of medical implants and devices. One focuses on their chemical structures and physical properties and discusses future directions offered by these emerging techniques.