Design and Fabrication of Customized Tracheal Stents by Additive Manufacturing

Abstract Additive Manufacturing (AM) is already becoming part of our life from a technological, economic and social point of view. Nowadays, it is applied in several manufacturing sectors. In particular, AM shows huge opportunities in the medical field and for healthcare applications. Due to its capability to produce complex geometries directly working on medical 3D images and thanks to the possibility to 3D-print biocompatible materials, AM is a key technology for the fabrication both of external and internal medical devices. In particular, the use of AM for medical applications is typically articulated in three steps: 3D-scanning of the patient anatomy, segmentation the medical scan and elaboration through CAD software for the preparation of a STL file suitable for the AM process. One of the main research topic in this field is the definition and optimization of procedures that, taking precise data from an individual patient, could be applied to the design and fabrication of customized components for medical applications. Therefore, this paper presents a project aimed at the fabrication of customized tracheal stents starting from the actual patient anatomy. In particular, it follows an approach based on molds FDM fabrication followed by biocompatible silicone casting. Molds were designed to obtain a tracheal stent based the patient anatomical tracheal lumen and were fabricated using FDM technology. Moreover, since the surface roughness is one of the most critical aspects related to the FDM, the produced molds were finished with a chemical surface post-treatment based on the use of acetone vapours. Overall, the whole developed procedure results in an effective custom-made medical devices realization

fem simulation of micromilling of cuzn37 brass considering tool run out

Abstract Micro-milling process of CuZn37 brass is considered important due to applications in tool production for micro replication technology. Variation in material properties, work material adhesion to tool surfaces, burr formation, and tool wear result in loss of productivity. Chip shapes together with localized temperature, plastic strain, and cutting forces during micro milling process can be predicted using Finite Element (FE) modelling and simulation. However, tool-workpiece engagement suffers from tool run-out affecting process performance in surface generation. This work provides experimental investigations on effects of tool run-out as well as process insight obtained from 3D FE simulations with and without considering tool run-out. Scanning electron microscope (SEM) observation of the 3D chip shapes demonstrates ductile deformed surfaces together with localized serration behavior. FE simulations are utilized to investigate the effects of cutting speed on cutting forces. Cutting force and chip morphology results from simulations are compared with force measurements, and actual chip morphology acquired by SEM revealing reasonable agreements

Design for Additive Manufacturing: Thermoforming Mold Optimization via Conformal Cooling Channel Technology

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Production and characterization of lattice samples with solid shell in 17-4 PH stainless steel by Laser Powder Bed Fusion technology

In this work, 17-4 PH stainless steel square-based lattice structures with solid shell were manufactured by Laser Powder Bed Fusion. Face Centered Cubic unit cell was chosen as lattice cell geometry. The main aim of this work was to study the role of the shell in the mechanical behavior under compression load and to identify any critical issue due to the connection of the shell with lattice part. This is a relevant topic since often lattice structure are integrated with solid walls and the study of the relative behavior can support the understating of the performance of complex components. The manufactured samples were tested in as-built and heat-treated condition. In detail, solution and aging treatment was performed as a conventional route for 17-4PH steel. In particular, microhardness and compressive tests were performed, and the mechanical behavior and the fracture mechanisms of the samples were investigated. Furthermore, the defects, the geometry of the struts and the connection with the solid part were analyzed. The detachment of the shell from the lattice did not occur. In fact, the solid part followed the deformation of the structure. The microstructural evolution after heat treatment was found to be responsible for an increase in hardness, strength and deformation for the investigated structures

Compressive behavior of Co-Cr-Mo radially graded porous structures under as-built and heat-treated conditions

Additive manufacturing research is continuously growing, and this field requires a full improvement of the capability and reliability of the processes involved. Of particular interest is the study of complex geometries production, such as lattice structures, which may have a potentially huge field of application, especially for biomedical products.In this work, the powder bed fusion technique was utilized to manufacture lattice structures with defined building angles concerning the build platform. A biocompatible Co-Cr-Mo alloy was used. Three different types of elementary cell geometry were selected: Face Centered Cubic, Diagonal, and Diamond. These cells were applied to the radially oriented lattice structures to evaluate the influence of their orientation in relation to the sample and the build platform. Moreover, heat treatment was carried out to study its influence on microstructural properties and mechanical behavior. Microhardness was measured, and compressive tests were performed to detect load response and to analyse the fracture mechanisms of these structures.The results show that the mechanical properties are highly influenced by the cell orientation in relation to the building direction and that the properties can be further tuned via HT. The favorable combination of mechanical properties and biocompatibility suggests that Co-Cr-Mo lattices may represent an optimal solution to produce customized metal implants

Laser texturing of a multilayer DLC from nano-liquid-diamond precursors via microsecond laser pulses

Diamond Like Carbon (DLC) coatings have well known mechanical properties, including high hardness, chemical stability, optical transparency and biocompatibility. In addition they are frequently used in multilayer coating systems. Laser surface texturing of DLC coatings can be a tailoring solution to optimize the coating functional parameters like roughness, wettability, wear, corrosion resistance, etc. Furthermore, compared to mechanical grinding, local laser removal could be a suitable technology for repairing locally damaged coated parts (i.e. worn surfaces, corroded surfaces, etc.) In the present work, laser surface texturing and controlled laser removal of a multilayer DLC coating obained from nano-liquid-diamond precursors have been studied using a 8W Q-switched laser (λ=532 nm) with microsecond pulses. Textured ablation as well as full planar decoating are shown through proper adjustment of laser texturing parameters

Covid-19 vaccination during pregnancy: A mixed-methods study of attitudes in a sample of Italian women and the role of health professionals’ communication

Objectives: We examined Italian pregnant women’s attitudes about the diphtheria, tetanus, and pertussis (DTP) vaccine, seasonal influenza, and Covid-19 vaccines, healthcare professionals’ (HP) communication, reasons and potential predictors for non-adherence. Methods: From August 2021 to January 2022, we carried out a cross-sectional study in Italy using an online self administered questionnaire addressed to women of age and pregnant, designed using LimeSurvey and dissem inated through social media. Questions explored vaccination attitude/perceptions, satisfaction, and trust in HPs’ information. Thematic analysis of free-text responses was performed using MaxQDA 2022. Statistical analyses were performed using STATA. Results: 1594 responses were obtained. 52% of women hesitated to be vaccinated against Covid-19 while pregnant. Information received by HPs was deemed incomplete by 56% of participants, unclear by 52%, and untrustworthy by 46%; 49% felt unsupported in their decision-making process. This variable was one predictor of vaccine hesitancy together with concern about vaccine safety in the multivariate model. The analysis of open ended questions revealed a pervasive feeling of dissatisfaction. Conclusion: The perceived lack of adequate communication and support by HPs affected pregnant women’s decision-making process on Covid-19 vaccination. Practice implications: HPs need to understand and communicate the importance of vaccination during pregnancy, learning to better tailor their messages