Development and evaluation of PVA-H 3D printed blood vessel biomodels with several stiffness

Biomodels, which are models of tissues such as blood vessels, have recently come into high demand for surgical training or medical device assessment use. Since the stiffness of blood vessels is not uniform, reproducing this nonuniformity would be advantageous to producing more realistic models, and to do this, we used a poly (vinyl alcohol) hydrogel (PVA-H) 3D printer. As a material, recently, PVA-H has received increasing attention. This printing technique may be suitable for fabricating models composed of parts exhibiting different levels of stiffness (multipart models). However, the PVA-H 3D printer uses outer molds as supports. Outer mold removal as a post-process might affect the mechanical properties of the models or other post-processes such as ethanol substitution, and this requires investigation. Quality checks on the mechanical properties of the final product are also necessary. In this study, the effect of outer molds on the efficiency of ethanol substitution was estimated by measuring specimen weights. Additionally, the effect of the heat generated when molds were removed with an ultrasonic cleaner on the Young's modulus of models was tested using tensile tests. Moreover, multipart pieces were fabricated, and their mechanical properties were measured. The findings were that ethanol substitution was able to be completed by conventional methods. Furthermore, the heat generation did not change the Young's modulus of the models. Also, it was possible to fabricate multipart PVA-H models, and their level of stiffness followed the theoretical equation that assumes constant stiffness and independency of each part. The PVA-H 3D printer, therefore, has the potential to fabricate multipart models that will enable better surgical training and device assessments.