Cyril Santos

A new design of an electrospinning apparatus for tissue engineering applications

The electrospinning technique is being widely explored in the biomedical field due to its simplicity to produce meshes and its capacity to mimic the micro-nanostructure of the natural extracellular matrix. For skin tissue engineering applications, wound dressings made from electrospun nanofibers present several advantages compared to conventional dressings, such as the promotion of the hemostasis phase, wound exudate absorption, semi-permeability, easy conformability to the wound, functional ability and no scar induction. Despite being a relatively simple technique, electrospinning is strongly influenced by polymer solution characteristics, processing parameters and environmental conditions, which strongly determine the production of fibers and their morphology. However, most electrospinning systems are wrongly designed, presenting a large number of conductive components that compromises the stability of the spinning process. This paper presents a new design of an electrospinning system solving the abovementioned limitations. The system was assessed through the production of polycaprolactone (PCL) and gelatin nanofibers. Different solvents and processing parameters were considered. Results show that the proposed electrospinning system is suitable to produce reproducible and homogeneous electrospun fibers for tissue engineering applications.

Numerical modeling of mechanical and thermal behaviors of cellular structures produced by SLM

The plastic injection molding industries is nowadays one of the strongest Portuguese industries and internationally known for their good quality products. Currently an injection mold is a solid, which is heavy and expensive to produce structure due to the use of conventional subtraction material processes. The need to produce more parts with high quality in a short period of time and at a lower cost requires the continuous development on geometries, materials and manufacturing processes of injection molds. The optimization of mold cooling processing can undoubtedly lead to a reduction of the effective total time of the injection process, enabling a shorter manufacturing time, which leads to a reduction of production costs. Combining the requirements of injection mold production with the advantages of Additive Manufacturing (AM) technologies, the Selective Laser Melting (SLM) emerges as a quicker and sustainable alternative to the construction of these structures. In this work two types of cellular internal topologies - hexagonal and cub-octahedral – to be manufacturing by SLM were generated and their mechanical and thermal behaviors numerically evaluated through compression and thermal analyses. Numerical simulation results demonstrated that the hexagonal cellular internal topology provides a higher mechanical strength when compared to the cub-octahedral cellular structure while the thermal analysis shows that cub-octahedral topology is more efficient for heat dissipation.The plastic injection molding industries is nowadays one of the strongest Portuguese industries and internationally known for their good quality products. Currently an injection mold is a solid, which is heavy and expensive to produce structure due to the use of conventional subtraction material processes. The need to produce more parts with high quality in a short period of time and at a lower cost requires the continuous development on geometries, materials and manufacturing processes of injection molds. The optimization of mold cooling processing can undoubtedly lead to a reduction of the effective total time of the injection process, enabling a shorter manufacturing time, which leads to a reduction of production costs. Combining the requirements of injection mold production with the advantages of Additive Manufacturing (AM) technologies, the Selective Laser Melting (SLM) emerges as a quicker and sustainable alternative to the construction of these structures. In this work two types of cellular interna...