Photocurable and elastic polyurethane based on polyether glycol with adjustable hardness for 3D printing customized flatfoot orthosis

Future trends of additive manufacturing in medical applications: An overview

Additive Manufacturing (AM) has recently demonstrated significant medical progress. Due to advancements in materials and methodologies, various processes have been developed to cater to the medical sector's requirements, including bioprinting and 4D, 5D, and 6D printing. However, only a few studies have captured these emerging trends and their medical applications. Therefore, this overview presents an analysis of the advancements and achievements obtained in AM for the medical industry, focusing on the principal trends identified in the annual report of AM3DP.

3D Printing of High Viscosity UV-Curable Resin for Highly Stretchable and Resilient Elastomer

Elastomers prepared via vat photopolymerizationus ually exhibit unsatisfied mechanical properties owing to their insufficient growth of molecular weight upon UV exposure. Increasing the weight ratio of oligomer in the resin system is an effective approach to enhance the mechanical properties, yet the viscosity of the UV-curable resin increases dramatically; this hinders its printing. In this study, a linear scan-based vat photopolymerization (LSVP) system which can print high-viscosity resins is implemented to 3D print the oligomer-dominated UV-curable resin via a dual-curing mechanism. A polyurethane methacrylate blocking oligomer is first synthesized and then mixed with a commercialized bifunctional oligomer, photoinitiator, and primary amine as a chain extender to prepare high-viscosity UV-curable resin for the LSVP system. The deblocked isocyanate is further crosslinked with a chain extender via thermal treatment to construct a highly entangled polymer chain network. The optimal thermal treatment parameters are investigated, and the resilience of the 3D-printed elastomer is evaluated through continuous tensile loading and unloading tests. Subsequently, complex structured elastomers are printed, exhibiting favorable mechanical durability without defects. The results obtained from this work will provide a reference for preparing elastomeric devices with excellent physical properties and expand the application scope of vat photopolymerization to new fields.

3D Printing of Individual Running Insoles - A Case Study

Purpose

The study's starting point is to find a low-cost and best-fit solution for comfortable movement for a recreational runner with knee pain using an orthopedic device. It is a case study. The research aims to apply digitization, CAD/CAM tools, and 3D printing to create an individual 3D running insole. The objective is to incorporate flexible shape optimization would provide comfort reductions in foot plantar pressures in one subject with knee pain while running. The test hypothesis was if it is possible to make it from one material. For this purpose, we created a new digital workflow based on the Decision Tree method and analyzed pain and comfort scores during user testing of prototypes.

Patient and Methods

The input data were obtained during a professional examination by a specialist doctor in the orthopedic outpatient clinic in the motion laboratory (DIERS 4D Motion Lab, Germany) with the output of data on the proband's complex movement stereotype. Surface and volumetric data were obtained in the biomedical laboratory with the 3D scanner. We modified the digital 3D foot models in 3D mesh software, developed the design in SW Gensole (Gyrobot, UK), and finally incorporated the internal structure and the surface layer of the insole data of the knowledge from the medical examination, comfort analyses, and scientific studies findings.

Results

Four complete 3D-printed prototypes (n=4) with differences in density and correction elements were designed. All of them were fabricated on a 3D printer (Prusa i3 MK3S, Czech Republic) with flexible TPU material suitable for skin contact. The Participant tested each of them five times in the field during a workout and final insoles three months on the routine training.

Conclusion

A novel workflow was created for designing, producing, and testing full 3D-printed insoles. The product is fit for immediate use.